{"id":2326,"date":"2015-05-06T03:51:01","date_gmt":"2015-05-06T03:51:01","guid":{"rendered":"https:\/\/courses.candelalearning.com\/oschemtemp\/?post_type=chapter&#038;p=2326"},"modified":"2016-10-27T15:35:02","modified_gmt":"2016-10-27T15:35:02","slug":"periodicity-2","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/chapter\/periodicity-2\/","title":{"raw":"Periodicity","rendered":"Periodicity"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\nBy the end of this module, you will be able to:\r\n<ul>\r\n \t<li>Classify elements<\/li>\r\n \t<li>Make predictions about the periodicity properties of the representative elements<\/li>\r\n<\/ul>\r\n<\/div>\r\nWe begin this section by examining the behaviors of representative metals in relation to their positions in the periodic table. The primary focus of this section will be the application of periodicity to the representative metals.\r\n\r\nIt is possible to divide elements into groups according to their electron configurations. The <b>representative elements<\/b> are elements where the <em>s<\/em> and <em>p<\/em> orbitals are filling. The transition elements are elements where the <em>d<\/em> orbitals (groups 3\u201311 on the periodic table) are filling, and the inner transition metals are the elements where the <em>f<\/em> orbitals are filling. The <em>d<\/em> orbitals fill with the elements in group 11; therefore, the elements in group 12 qualify as representative elements because the last electron enters an <em>s<\/em> orbital. Metals among the representative elements are the <b>representative metals<\/b>. Metallic character results from an element\u2019s ability to lose its outer valence electrons and results in high thermal and electrical conductivity, among other physical and chemical properties. There are 20 nonradioactive representative metals in groups 1, 2, 3, 12, 13, 14, and 15 of the periodic table (the elements shaded in yellow in Figure\u00a01). The radioactive elements copernicium, flerovium, polonium, and livermorium are also metals but are beyond the scope of this chapter.\r\n\r\nIn addition to the representative metals, some of the representative elements are metalloids. A <b>metalloid<\/b> is an element that has properties that are between those of metals and nonmetals; these elements are typically semiconductors.\r\n\r\nThe remaining representative elements are nonmetals. Unlike <b>metals<\/b>, which typically form cations and ionic compounds (containing ionic bonds), nonmetals tend to form anions or molecular compounds. In general, the combination of a metal and a nonmetal produces a salt. A <b>salt<\/b> is an ionic compound consisting of cations and anions.\r\n\r\n[caption id=\"attachment_5038\" align=\"aligncenter\" width=\"1024\"]<img class=\"size-large wp-image-5038\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/08\/23214511\/CNX_Chem_18_01_PeriodicPU3-1024x840.jpg\" alt=\"The Periodic Table\u00a0of Elements is shown. The 18 columns are labeled \u201cGroup\u201d and the 7 rows are labeled \u201cPeriod.\u201d Below the table to the right is a box labeled \u201cColor Code\u201d with different colors for representative metals, transition and inner transition metals, radioactive elements, metalloids, and nonmetals, as well as solids, liquids, and gases. Each element will be described in this order: atomic number; name; symbol; whether it is a representative metal, transition and inner transition metal, radioactive element, metalloid, or nonmetal; whether it is a solid, liquid, or gas; and atomic mass. Beginning at the top left of the table, or period 1, group 1, is a box containing \u201c1; hydrogen; H; nonmetal; gas; and 1.008.\u201d There is only one other element box in period 1, group 18, which contains \u201c2; helium; H e; nonmetal; gas; and 4.003.\u201d Period 2, group 1 contains \u201c3; lithium; L i; representative metal; solid; and 6.94\u201d Group 2 contains \u201c4; beryllium; B e; representative metal; solid; and 9.012.\u201d Groups 3 through 12 are skipped and group 13 contains \u201c5; boron; B; metalloid; solid; 10.81.\u201d Group 14 contains \u201c6; carbon; C; nonmetal; solid; and 12.01.\u201d Group 15 contains \u201c7; nitrogen; N; nonmetal; gas; and 14.01.\u201d Group 16 contains \u201c8; oxygen; O; nonmetal; gas; and 16.00.\u201d Group 17 contains \u201c9; fluorine; F; nonmetal; gas; and 19.00.\u201d Group 18 contains \u201c10; neon; N e; nonmetal; gas; and 20.18.\u201d Period 3, group 1 contains \u201c11; sodium; N a; representative metal; solid; and 22.99.\u201d Group 2 contains \u201c12; magnesium; M g; representative metal; solid; and 24.31.\u201d Groups 3 through 12 are skipped again in period 3 and group 13 contains \u201c13; aluminum; A l; representative metal; solid; and 26.98.\u201d Group 14 contains \u201c14; silicon; S i; metalloid; solid; and 28.09.\u201d Group 15 contains \u201c15; phosphorous; P; nonmetal; solid; and 30.97.\u201d Group 16 contains \u201c16; sulfur; S; nonmetal; solid; and 32.06.\u201d Group 17 contains \u201c17; chlorine; C l; nonmetal; gas; and 35.45.\u201d Group 18 contains \u201c18; argon; A r; nonmetal; gas; and 39.95.\u201d Period 4, group 1 contains \u201c19; potassium; K; representative metal; solid; and 39.10.\u201d Group 2 contains \u201c20; calcium; C a; representative metal; solid; and 40.08.\u201d Group 3 contains \u201c21; scandium; S c; transition and inner transition metal; solid; and 44.96.\u201d Group 4 contains \u201c22; titanium; T i; transition and inner transition metal; solid; and 47.87.\u201d Group 5 contains \u201c23; vanadium; V; transition and inner transition metal; solid; and 50.94.\u201d Group 6 contains \u201c24; chromium; C r; transition and inner transition metal; solid; and 52.00.\u201d Group 7 contains \u201c25; manganese; M n; transition and inner transition metal; solid; and 54.94.\u201d Group 8 contains \u201c26; iron; F e; transition and inner transition metal; solid; and 55.85.\u201d Group 9 contains \u201c27; cobalt; C o; transition and inner transition metal; solid; and 58.93.\u201d Group 10 contains \u201c28; nickel; N i; transition and inner transition metal; solid; and 58.69.\u201d Group 11 contains \u201c29; copper; C u; transition and inner transition metal; solid; and 63.55.\u201d Group 12 contains \u201c30; zinc; Z n; transition and inner transition metal; solid; and 65.38.\u201d Group 13 contains \u201c31; gallium; G a; representative metal; solid; and 69.72.\u201d Group 14 contains \u201c32; germanium; G e; metalloid; solid; and 72.63.\u201d Group 15 contains \u201c33; arsenic; A s; metalloid; solid; and 74.92.\u201d Group 16 contains \u201c34; selenium; S e; nonmetal; solid; and 78.97.\u201d Group 17 contains \u201c35; bromine; B r; nonmetal; liquid; and 79.90.\u201d Group 18 contains \u201c36; krypton; K r; nonmetal; gas; and 83.80.\u201d Period 5, group 1 contains \u201c37; rubidium; R b; representative metal; solid; and 85.47.\u201d Group 2 contains \u201c38; strontium; S r; representative metal; solid; and 87.62.\u201d Group 3 contains \u201c39; yttrium; Y; transition and inner transition metal; solid; and 88.91.\u201d Group 4 contains \u201c40; zirconium; Z r; transition and inner transition metal; solid; and 91.22.\u201d Group 5 contains \u201c41; niobium; N b; transition and inner transition metal; solid; and 92.91.\u201d Group 6 contains \u201c42; molybdenum; M o; transition and inner transition metal; solid; and 95.95.\u201d Group 7 contains \u201c43; technetium; T c; radioactive element; solid; and 97.\u201d Group 8 contains \u201c44; ruthenium; R u; transition and inner transition metal; solid; and 101.1.\u201d Group 9 contains \u201c45; rhodium; R h; transition and inner transition metal; solid; and 102.9.\u201d Group 10 contains \u201c46; palladium; P d; transition and inner transition metal; solid; and 106.4.\u201d Group 11 contains \u201c47; silver; A g; transition and inner transition metal; solid; and 107.9.\u201d Group 12 contains \u201c48; cadmium; C d; transition and inner transition metal; solid; and 112.4.\u201d Group 13 contains \u201c49; indium; I n; representative metal; solid; and 114.8.\u201d Group 14 contains \u201c50; tin; S n; representative metal; solid; and 118.7.\u201d Group 15 contains \u201c51; antimony; S b; metalloid; solid; and 121.8.\u201d Group 16 contains \u201c52; tellurium; T e; metalloid; solid; and 127.6.\u201d Group 17 contains \u201c53; iodine; I; nonmetal; solid; and 126.9.\u201d Group 18 contains \u201c54; xenon; X e; nonmetal; gas; and 131.3.\u201d Period 6, group 1 contains \u201c55; cesium; C s; representative metal; solid; and 132.9.\u201d Group 2 contains \u201c56; barium; B a; representative metal; solid; and 137.3.\u201d Group 3 breaks the pattern. The box has a large arrow pointing to a row of elements below the table with atomic numbers ranging from 57-71. In sequential order by atomic number, the first box in this row contains \u201c57; lanthanum; L a; representative metal; solid; and 138.9.\u201d To its right, the next is \u201c58; cerium; C e; representative metal; solid; and 140.1.\u201d Next is \u201c59; praseodymium; P r; representative metal; solid; and 140.9.\u201d Next is \u201c60; neodymium; N d; representative metal; solid; and 144.2.\u201d Next is \u201c61; promethium; P m; radioactive element; solid; and 145.\u201d Next is \u201c62; samarium; S m; representative metal; solid; and 150.4.\u201d Next is \u201c63; europium; E u; representative metal; solid; and 152.0.\u201d Next is \u201c64; gadolinium; G d; representative metal; solid; and 157.3.\u201d Next is \u201c65; terbium; T b; representative metal; solid; and 158.9.\u201d Next is \u201c66; dysprosium; D y; representative metal; solid; and 162.5.\u201d Next is \u201c67; holmium; H o; representative metal; solid; and 164.9.\u201d Next is \u201c68; erbium; E r; representative metal; solid; and 167.3.\u201d Next is \u201c69; thulium; T m; representative metal; solid; and 168.9.\u201d Next is \u201c70; ytterbium; Y b; representative metal; solid; and 173.1.\u201d The last in this special row is \u201c71; lutetium; L u; representative metal; solid; and 175.0.\u201d Continuing in period 6, group 4 contains \u201c72; hafnium; H f; transition and inner transition metal; solid; and 178.5.\u201d Group 5 contains \u201c73; tantalum; T a; transition and inner transition metal; solid; and 180.9.\u201d Group 6 contains \u201c74; tungsten; W; transition and inner transition metal; solid; and 183.8.\u201d Group 7 contains \u201c75; rhenium; R e; transition and inner transition metal; solid; and 186.2.\u201d Group 8 contains \u201c76; osmium; O s; transition and inner transition metal; solid; and 190.2.\u201d Group 9 contains \u201c77; iridium; I r; transition and inner transition metal; solid; and 192.2.\u201d Group 10 contains \u201c78; platinum; P t; transition and inner transition metal; solid; and 195.1.\u201d Group 11 contains \u201c79; gold; A u; transition and inner transition metal; solid; and 197.0.\u201d Group 12 contains \u201c80; mercury; H g; transition and inner transition metal; liquid; and 200.6.\u201d Group 13 contains \u201c81; thallium; T l; representative metal; solid; and 204.4.\u201d Group 14 contains \u201c82; lead; P b; representative metal; solid; and 207.2.\u201d Group 15 contains \u201c83; bismuth; B i; representative metal; solid; and 209.0.\u201d Group 16 contains \u201c84; polonium; P o; radioactive element; solid; and 209.\u201d Group 17 contains \u201c85; astatine; A t; radioactive element; solid; and 210.\u201d Group 18 contains \u201c86; radon; R n; radioactive element; gas; and 222.\u201d Period 7, group 1 contains \u201c87; francium; F r; radioactive element; solid; and 223.\u201d Group 2 contains \u201c88; radium; R a; radioactive element; solid; and 226.\u201d Group 3 breaks the pattern much like what occurs in period 6. A large arrow points from the box in period 7, group 3 to a special row containing the elements with atomic numbers ranging from 89-103, just below the row which contains atomic numbers 57-71. In sequential order by atomic number, the first box in this row contains \u201c89; actinium; A c; radioactive element; solid; and 227.\u201d To its right, the next is \u201c90; thorium; T h; radioactive element; solid; and 232.0.\u201d Next is \u201c91; protactinium; P a; radioactive element; solid; and 231.0.\u201d Next is \u201c92; uranium; U; radioactive element; solid; and 238.0.\u201d Next is \u201c93; neptunium; N p; radioactive element; solid; and N p.\u201d Next is \u201c94; plutonium; P u; radioactive element; solid; and 244.\u201d Next is \u201c95; americium; A m; radioactive element; solid; and 243.\u201d Next is \u201c96; curium; C m; radioactive element; solid; and 247.\u201d Next is \u201c97; berkelium; B k; radioactive element; solid; and 247.\u201d Next is \u201c98; californium; C f; radioactive element; solid; and 251.\u201d Next is \u201c99; einsteinium; E s; radioactive element; solid; and 252.\u201d Next is \u201c100; fermium; F m; radioactive element; solid; and 257.\u201d Next is \u201c101; mendelevium; M d; radioactive element; solid; and 258.\u201d Next is \u201c102; nobelium; N o; radioactive element; solid; and 259.\u201d The last in this special row is \u201c103; lawrencium; L r; radioactive element; solid; and 262.\u201d Continuing in period 7, group 4 contains \u201c104; rutherfordium; R f; transition and inner transition metal; solid; and 267.\u201d Group 5 contains \u201c105; dubnium; D b; transition and inner transition metal; solid; and 270.\u201d Group 6 contains \u201c106; seaborgium; S g; transition and inner transition metal; solid; and 271.\u201d Group 7 contains \u201c107; bohrium; B h; transition and inner transition metal; solid; and 270.\u201d Group 8 contains \u201c108; hassium; H s; transition and inner transition metal; solid; and 277.\u201d Group 9 contains \u201c109; meitnerium; M t; radioactive element; solid; and 276.\u201d Group 10 contains \u201c110; darmstadtium; D s; radioactive element; solid; and 281.\u201d Group 11 contains \u201c111; roentgenium; R g; radioactive element; solid; and 282.\u201d Group 12 contains \u201c112; copernicium; C n; radioactive element; liquid; and 285.\u201d Group 13 contains \u201c113; ununtrium; U u t; radioactive element; solid; and 285.\u201d Group 14 contains \u201c114; flerovium; F l; radioactive element; solid; and 289.\u201d Group 15 contains \u201c115; ununpentium; U u p; radioactive element; solid; and 288.\u201d Group 16 contains \u201c116; livermorium; L v; radioactive element; solid; and 293.\u201d Group 17 contains \u201c117; ununseptium; U u s; radioactive; solid; and 294.\u201d Group 18 contains \u201c118; ununoctium; U u o; radioactive element; solid; and 294.\u201d\" width=\"1024\" height=\"840\" \/> Figure\u00a01. The location of the representative metals is shown in the periodic table. Nonmetals are shown in green, metalloids in purple, and the transition metals and inner transition metals in yellow.[\/caption]\r\n\r\nMost of the representative metals do not occur naturally in an uncombined state because they readily react with water and oxygen in the air. However, it is possible to isolate elemental beryllium, magnesium, zinc, cadmium, mercury, aluminum, tin, and lead from their naturally occurring minerals and use them because they react very slowly with air. Part of the reason why these elements react slowly is that these elements react with air to form a protective coating. The formation of this protective coating is <b>passivation<\/b>. The coating is a nonreactive film of oxide or some other compound. Elemental magnesium, aluminum, zinc, and tin are important in the fabrication of many familiar items, including wire, cookware, foil, and many household and personal objects. Although beryllium, cadmium, mercury, and lead are readily available, there are limitations in their use because of their toxicity.\r\n<h2 data-type=\"title\">Group 1: The Alkali Metals<\/h2>\r\nThe alkali metals lithium, sodium, potassium, rubidium, cesium, and francium constitute group 1 of the periodic table. Although hydrogen is in group 1 (and also in group 17), it is a nonmetal and deserves separate consideration later in this chapter. The name alkali metal is in reference to the fact that these metals and their oxides react with water to form very basic (alkaline) solutions.\r\n\r\n[caption id=\"attachment_2317\" align=\"alignright\" width=\"400\"]<img class=\" wp-image-2317\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212450\/CNX_Chem_18_01_LithiumRx1.jpg\" alt=\"A glass container that is half filled with a colorless liquid is shown. Blocks of a shiny silver solid float on top of the liquid in the container.\" width=\"400\" height=\"222\" \/> Figure\u00a02. Lithium floats in paraffin oil because its density is less than the density of paraffin oil.[\/caption]\r\n\r\nThe properties of the alkali metals are similar to each other as expected for elements in the same family. The alkali metals have the largest atomic radii and the lowest first ionization energy in their periods. This combination makes it very easy to remove the single electron in the outermost (valence) shell of each. The easy loss of this valence electron means that these metals readily form stable cations with a charge of 1+. Their reactivity increases with increasing atomic number due to the ease of losing the lone valence electron (decreasing ionization energy). Since oxidation is so easy, the reverse, reduction, is difficult, which explains why it is hard to isolate the elements. The solid alkali metals are very soft; lithium, shown in Figure\u00a02, has the lowest density of any metal (0.5 g\/cm<sup>3<\/sup>).\r\n\r\nThe alkali metals all react vigorously with water to form hydrogen gas and a basic solution of the metal hydroxide. This means they are easier to oxidize than is hydrogen. As an example, the reaction of lithium with water is:\r\n<p style=\"text-align: center;\">[latex]\\text{2Li}\\left(s\\right)+{\\text{2H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{2LiOH}\\left(aq\\right)+{\\text{H}}_{2}\\left(g\\right)[\/latex]<\/p>\r\nAlkali metals react directly with all the nonmetals (except the noble gases) to yield binary ionic compounds containing 1+ metal ions. These metals are so reactive that it is necessary to avoid contact with both moisture and oxygen in the air. Therefore, they are stored in sealed containers under mineral oil, as shown in Figure\u00a03, to prevent contact with air and moisture. The pure metals never exist free (uncombined) in nature due to their high reactivity. In addition, this high reactivity makes it necessary to prepare the metals by electrolysis of alkali metal compounds.\r\n\r\n[caption id=\"attachment_5901\" align=\"aligncenter\" width=\"549\"]<img class=\" wp-image-5901\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/218\/2016\/10\/24205154\/CNX_Chem_18_01_AlkMetStor1-1024x633.jpg\" alt=\"A sealed, tube-like glass container is shown. The container is partially filled with a colorless liquid and contains two metallic spheres.\" width=\"549\" height=\"340\" \/> Figure\u00a03. To prevent contact with air and water, potassium for laboratory use comes as sticks or beads stored under kerosene or mineral oil, or in sealed containers. (credit: http:\/\/images-of-elements.com\/potassium.php)[\/caption]\r\n\r\n<div class=\"textbox\">\r\n\r\nThis video demonstrates the reactions of the alkali metals with water.\r\n\r\nhttps:\/\/youtu.be\/Vxqe_ZOwsHs\r\n\r\n<\/div>\r\n\r\n[caption id=\"attachment_2319\" align=\"alignright\" width=\"200\"]<img class=\"wp-image-2319\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212453\/CNX_Chem_18_01_NaFlame1.jpg\" alt=\"A photo of a lit Bunsen burner is shown. A wooden splint is placed in the flame, and a yellow flame is produced.\" width=\"200\" height=\"594\" \/> Figure\u00a04. Dipping a wire into a solution of a sodium salt and then heating the wire causes emission of a bright yellow light, characteristic of sodium.[\/caption]\r\n\r\nUnlike many other metals, the reactivity and softness of the alkali metals make these metals unsuitable for structural applications. However, there are applications where the reactivity of the alkali metals is an advantage. For example, the production of metals such as titanium and zirconium relies, in part, on the ability of sodium to reduce compounds of these metals. The manufacture of many organic compounds, including certain dyes, drugs, and perfumes, utilizes reduction by lithium or sodium.\r\n\r\nSodium and its compounds impart a bright yellow color to a flame, as seen in Figure\u00a04. Passing an electrical discharge through sodium vapor also produces this color. In both cases, this is an example of an emission spectrum as discussed in the chapter on electronic structure. Streetlights sometime employ sodium vapor lights because the sodium vapor penetrates fog better than most other light. This is because the fog does not scatter yellow light as much as it scatters white light. The other alkali metals and their salts also impart color to a flame. Lithium creates a bright, crimson color, whereas the others create a pale, violet color.\r\n<h2 data-type=\"title\">Group 2: The Alkaline Earth Metals<\/h2>\r\nThe <b>alkaline earth metals<\/b> (beryllium, magnesium, calcium, strontium, barium, and radium) constitute group 2 of the periodic table. The name alkaline metal comes from the fact that the oxides of the heavier members of the group react with water to form alkaline solutions. The nuclear charge increases when going from group 1 to group 2. Because of this charge increase, the atoms of the alkaline earth metals are smaller and have higher first ionization energies than the alkali metals within the same period. The higher ionization energy makes the alkaline earth metals less reactive than the alkali metals; however, they are still very reactive elements. Their reactivity increases, as expected, with increasing size and decreasing ionization energy. In chemical reactions, these metals readily lose both valence electrons to form compounds in which they exhibit an oxidation state of 2+. Due to their high reactivity, it is common to produce the alkaline earth metals, like the alkali metals, by electrolysis. Even though the ionization energies are low, the two metals with the highest ionization energies (beryllium and magnesium) do form compounds that exhibit some covalent characters. Like the alkali metals, the heavier alkaline earth metals impart color to a flame. As in the case of the alkali metals, this is part of the emission spectrum of these elements. Calcium and strontium produce shades of red, whereas barium produces a green color.\r\n\r\nMagnesium is a silver-white metal that is malleable and ductile at high temperatures. Passivation decreases the reactivity of magnesium metal. Upon exposure to air, a tightly adhering layer of magnesium oxycarbonate forms on the surface of the metal and inhibits further reaction. (The carbonate comes from the reaction of carbon dioxide in the atmosphere.) Magnesium is the lightest of the widely used structural metals, which is why most magnesium production is for lightweight alloys.\r\n\r\nMagnesium (shown in Figure\u00a05), calcium, strontium, and barium react with water and air. At room temperature, barium shows the most vigorous reaction. The products of the reaction with water are hydrogen and the metal hydroxide. The formation of hydrogen gas indicates that the heavier alkaline earth metals are better reducing agents (more easily oxidized) than is hydrogen. As expected, these metals react with both acids and nonmetals to form ionic compounds. Unlike most salts of the alkali metals, many of the common salts of the alkaline earth metals are insoluble in water because of the high lattice energies of these compounds, containing a divalent metal ion.\r\n\r\n[caption id=\"attachment_2321\" align=\"aligncenter\" width=\"550\"]<img class=\" wp-image-2321\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212455\/CNX_Chem_18_01_CalciWater1.jpg\" alt=\"Three glass containers with lids are shown in a photo. A plus sign is drawn between the first two containers and a right-facing arrow is drawn between the second and third containers. The left container holds a black granular solid while the center container holds a clear, colorless liquid. The right container holds a clear, pink liquid.\" width=\"550\" height=\"412\" \/> Figure\u00a05. From left to right: Mg(<em>s<\/em>), warm water at pH 7, and the resulting solution with a pH greater than 7, as indicated by the pink color of the phenolphthalein indicator. (credit: modification of work by Sahar Atwa)[\/caption]\r\n\r\nThe potent reducing power of hot magnesium is useful in preparing some metals from their oxides. Indeed, magnesium\u2019s affinity for oxygen is so great that burning magnesium reacts with carbon dioxide, producing elemental carbon:\r\n<p style=\"text-align: center;\">[latex]\\text{2Mg}\\left(s\\right)+{\\text{CO}}_{2}\\left(g\\right)\\rightarrow\\text{2MgO}\\left(s\\right)+\\text{C}\\left(s\\right)[\/latex]<\/p>\r\nFor this reason, a CO<sub>2<\/sub> fire extinguisher will not extinguish a magnesium fire. Additionally, the brilliant white light emitted by burning magnesium makes it useful in flares and fireworks.\r\n<h2 data-type=\"title\">Group 12<\/h2>\r\n[caption id=\"attachment_2322\" align=\"alignright\" width=\"300\"]<img class=\"wp-image-2322\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212456\/CNX_Chem_18_01_ZincHCl1.jpg\" alt=\"A glass tube holding a metallic solid in a colorless liquid is shown laying on a black background with white lettering.\" width=\"300\" height=\"418\" \/> Figure\u00a06. Zinc is an active transition metal. It dissolves in hydrochloric acid, forming a solution of colorless Zn<sup>2+<\/sup> ions, Cl<sup>\u2212<\/sup> ions, and hydrogen gas.[\/caption]\r\n\r\nThe elements in group 12 are not transition elements because the last electron added is not a <em>d<\/em> electron, but an <em>s<\/em> electron. Since the last electron added is an <em>s<\/em> electron, these elements qualify as representative metals, or post-transition metals. The group 12 elements behave more like the alkaline earth metals than transition metals. Group 12 contains the four elements zinc, cadmium, mercury, and copernicium. Each of these elements has two electrons in its outer shell (<em>ns<\/em><sup>2<\/sup>). When atoms of these metals form cations with a charge of 2+, where the two outer electrons are lost, they have pseudo-noble gas electron configurations. Mercury is sometimes an exception because it also exhibits an oxidation state of 1+ in compounds that contain a diatomic [latex]{\\text{Hg}}_{2}{}^{2+}[\/latex] ion. In their elemental forms and in compounds, cadmium and mercury are both toxic.\r\n\r\nZinc is the most reactive in group 12, and mercury is the least reactive. (This is the reverse of the reactivity trend of the metals of groups 1 and 2, in which reactivity increases down a group. The increase in reactivity with increasing atomic number only occurs for the metals in groups 1 and 2.) The decreasing reactivity is due to the formation of ions with a pseudo-noble gas configuration and to other factors that are beyond the scope of this discussion. The chemical behaviors of zinc and cadmium are quite similar to each other but differ from that of mercury.\r\n\r\nZinc and cadmium have lower reduction potentials than hydrogen, and, like the alkali metals and alkaline earth metals, they will produce hydrogen gas when they react with acids. The reaction of zinc with hydrochloric acid, shown in Figure\u00a06, is:\r\n<p style=\"text-align: center;\">[latex]\\text{Zn}\\left(s\\right)+{\\text{2H}}_{3}{\\text{O}}^{+}\\left(aq\\right)+{\\text{2Cl}}^{-}\\left(aq\\right)\\rightarrow{\\text{H}}_{2}\\left(g\\right)+{\\text{Zn}}^{2+}\\left(aq\\right)+{\\text{2Cl}}^{-}\\left(aq\\right)+{\\text{2H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/p>\r\nZinc is a silvery metal that quickly tarnishes to a blue-gray appearance. This change in color is due to an adherent coating of a basic carbonate, Zn<sub>2<\/sub>(OH)<sub>2<\/sub>CO<sub>3<\/sub>, which passivates the metal to inhibit further corrosion. Dry cell and alkaline batteries contain a zinc anode. Brass (Cu and Zn) and some bronze (Cu, Sn, and sometimes Zn) are important zinc alloys. About half of zinc production serves to protect iron and other metals from corrosion. This protection may take the form of a sacrificial anode (also known as a galvanic anode, which is a means of providing cathodic protection for various metals) or as a thin coating on the protected metal. Galvanized steel is steel with a protective coating of zinc.\r\n<div class=\"textbox shaded\">\r\n<h3 data-type=\"title\">Sacrificial Anodes<\/h3>\r\nA sacrificial anode, or galvanic anode, is a means of providing cathodic protection of various metals. Cathodic protection refers to the prevention of corrosion by converting the corroding metal into a cathode. As a cathode, the metal resists corrosion, which is an oxidation process. Corrosion occurs at the sacrificial anode instead of at the cathode.\r\n\r\nThe construction of such a system begins with the attachment of a more active metal (more negative reduction potential) to the metal needing protection. Attachment may be direct or via a wire. To complete the circuit, a <em>salt bridge<\/em> is necessary. This salt bridge is often seawater or ground water. Once the circuit is complete, oxidation (corrosion) occurs at the anode and not the cathode.\r\n\r\nThe commonly used sacrificial anodes are magnesium, aluminum, and zinc. Magnesium has the most negative reduction potential of the three and serves best when the salt bridge is less efficient due to a low electrolyte concentration such as in freshwater. Zinc and aluminum work better in saltwater than does magnesium. Aluminum is lighter than zinc and has a higher capacity; however, an oxide coating may passivate the aluminum. In special cases, other materials are useful. For example, iron will protect copper.\r\n\r\n<\/div>\r\nMercury is very different from zinc and cadmium. Mercury is the only metal that is liquid at 25 \u00b0C. Many metals dissolve in mercury, forming solutions called amalgams (see the feature on Amalgams), which are alloys of mercury with one or more other metals. Mercury, shown in Figure\u00a07, is a nonreactive element that is more difficult to oxidize than hydrogen. Thus, it does not displace hydrogen from acids; however, it will react with strong oxidizing acids, such as nitric acid:\r\n<p style=\"text-align: center;\">[latex]\\text{Hg}\\left(l\\right)+\\text{HCl}\\left(aq\\right)\\rightarrow\\text{no reaction}[\/latex]\r\n[latex]\\text{3Hg}\\left(l\\right)+{\\text{8HNO}}_{3}\\left(aq\\right)\\rightarrow\\text{3Hg}{\\left({\\text{NO}}_{3}\\right)}_{2}\\left(aq\\right)+{\\text{4H}}_{2}\\text{O}\\left(l\\right)+\\text{2NO}\\left(g\\right)[\/latex]<\/p>\r\nThe clear NO initially formed quickly undergoes further oxidation to the reddish brown NO<sub>2<\/sub>.\r\n\r\n[caption id=\"attachment_2323\" align=\"aligncenter\" width=\"551\"]<img class=\" wp-image-2323\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212458\/CNX_Chem_18_01_MercuryRx1.jpg\" alt=\"Three test tubes are shown in a photo. The left tube contains a metallic liquid. The middle tube contains a metallic liquid under a layer of clear, colorless liquid. The third tube contains a whitish solid under a layer of yellowish liquid.\" width=\"551\" height=\"414\" \/> Figure\u00a07. From left to right: Hg(l), Hg<sup>+<\/sup> concentrated HCl, Hg<sup>+<\/sup> concentrated HNO<sub>3<\/sub>. (credit: Sahar Atwa)[\/caption]\r\n\r\nMost mercury compounds decompose when heated. Most mercury compounds contain mercury with a 2+-oxidation state. When there is a large excess of mercury, it is possible to form compounds containing the [latex]{\\text{Hg}}_{2}^{2+}[\/latex] ion. All mercury compounds are toxic, and it is necessary to exercise great care in their synthesis.\r\n<div class=\"textbox shaded\">\r\n<h3 data-type=\"title\">Amalgams<\/h3>\r\nAn amalgam is an alloy of mercury with one or more other metals. This is similar to considering steel to be an alloy of iron with other metals. Most metals will form an amalgam with mercury, with the main exceptions being iron, platinum, tungsten, and tantalum.\r\n\r\nDue to toxicity issues with mercury, there has been a significant decrease in the use of amalgams. Historically, amalgams were important in electrolytic cells and in the extraction of gold. Amalgams of the alkali metals still find use because they are strong reducing agents and easier to handle than the pure alkali metals.\r\n\r\nProspectors had a problem when they found finely divided gold. They learned that adding mercury to their pans collected the gold into the mercury to form an amalgam for easier collection. Unfortunately, losses of small amounts of mercury over the years left many streams in California polluted with mercury.\r\n\r\nDentists use amalgams containing silver and other metals to fill cavities. There are several reasons to use an amalgam including low cost, ease of manipulation, and longevity compared to alternate materials. Dental amalgams are approximately 50% mercury by weight, which, in recent years, has become a concern due to the toxicity of mercury.\r\n\r\nAfter reviewing the best available data, the Food and Drug Administration (FDA) considers amalgam-based fillings to be safe for adults and children over six years of age. Even with multiple fillings, the mercury levels in the patients remain far below the lowest levels associated with harm. Clinical studies have found no link between dental amalgams and health problems. Health issues may not be the same in cases of children under six or pregnant women. The FDA conclusions are in line with the opinions of the Environmental Protection Agency (EPA) and Centers for Disease Control (CDC). The only health consideration noted is that some people are allergic to the amalgam or one of its components.\r\n\r\n<\/div>\r\n<h2 data-type=\"title\">Group 13<\/h2>\r\nGroup 13 contains the metalloid boron and the metals aluminum, gallium, indium, and thallium. The lightest element, boron, is semiconducting, and its binary compounds tend to be covalent and not ionic. The remaining elements of the group are metals, but their oxides and hydroxides change characters. The oxides and hydroxides of aluminum and gallium exhibit both acidic and basic behaviors. A substance, such as these two, that will react with both acids and bases is amphoteric. This characteristic illustrates the combination of nonmetallic and metallic behaviors of these two elements. Indium and thallium oxides and hydroxides exhibit only basic behavior, in accordance with the clearly metallic character of these two elements. The melting point of gallium is unusually low (about 30 \u00b0C) and will melt in your hand.\r\n\r\nAluminum is amphoteric because it will react with both acids and bases. A typical reaction with an acid is:\r\n<p style=\"text-align: center;\">[latex]\\text{2Al}\\left(s\\right)+\\text{6HCl}\\left(aq\\right)\\rightarrow{\\text{2AlCl}}_{3}\\left(aq\\right)+{\\text{3H}}_{2}\\left(g\\right)[\/latex]<\/p>\r\nThe products of the reaction of aluminum with a base depend upon the reaction conditions, with the following being one possibility:\r\n<p style=\"text-align: center;\">[latex]\\text{2Al}\\left(s\\right)+\\text{2NaOH}\\left(aq\\right)+{\\text{6H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{2Na}\\left[\\text{Al}{\\left(\\text{OH}\\right)}_{4}\\right]\\left(aq\\right)+{\\text{3H}}_{2}\\left(g\\right)[\/latex]<\/p>\r\nWith both acids and bases, the reaction with aluminum generates hydrogen gas.\r\n\r\nThe group 13 elements have a valence shell electron configuration of <em>ns<\/em><sup>2<\/sup><em>np<\/em><sup>1<\/sup>. Aluminum normally uses all of its valence electrons when it reacts, giving compounds in which it has an oxidation state of 3+. Although many of these compounds are covalent, others, such as AlF<sub>3<\/sub> and Al<sub>2<\/sub>(SO<sub>4<\/sub>)<sub>3<\/sub>, are ionic. Aqueous solutions of aluminum salts contain the cation [latex]{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{6}\\right]}^{3+},[\/latex] abbreviated as Al<sup>3+<\/sup>(<em>aq<\/em>). Gallium, indium, and thallium also form ionic compounds containing M<sup>3+<\/sup> ions. These three elements exhibit not only the expected oxidation state of 3+ from the three valence electrons but also an oxidation state (in this case, 1+) that is two below the expected value. This phenomenon, the inert pair effect, refers to the formation of a stable ion with an oxidation state two lower than expected for the group. The pair of electrons is the valence <em>s<\/em> orbital for those elements. In general, the inert pair effect is important for the lower <em>p<\/em>-block elements. In an aqueous solution, the Tl<sup>+<\/sup>(<em>aq<\/em>) ion is more stable than is Tl<sup>3+<\/sup>(<em>aq<\/em>). In general, these metals will react with air and water to form 3+ ions; however, thallium reacts to give thallium(I) derivatives. The metals of group 13 all react directly with nonmetals such as sulfur, phosphorus, and the halogens, forming binary compounds.\r\n\r\nThe metals of group 13 (Al, Ga, In, and Tl) are all reactive. However, passivation occurs as a tough, hard, thin film of the metal oxide forms upon exposure to air. Disruption of this film may counter the passivation, allowing the metal to react. One way to disrupt the film is to expose the passivated metal to mercury. Some of the metal dissolves in the mercury to form an amalgam, which sheds the protective oxide layer to expose the metal to further reaction. The formation of an amalgam allows the metal to react with air and water.\r\n<div class=\"textbox\">\r\n\r\nAlthough easily oxidized, the passivation of aluminum makes it very useful as a strong, lightweight building material. Because of the formation of an amalgam, mercury is corrosive to structural materials made of aluminum. This video demonstrates how the integrity of an aluminum beam can be destroyed by the addition of a small amount of elemental mercury.\r\n\r\nhttps:\/\/youtu.be\/Z7Ilxsu-JlY\r\n\r\n<\/div>\r\nThe most important uses of aluminum are in the construction and transportation industries, and in the manufacture of aluminum cans and aluminum foil. These uses depend on the lightness, toughness, and strength of the metal, as well as its resistance to corrosion. Because aluminum is an excellent conductor of heat and resists corrosion, it is useful in the manufacture of cooking utensils.\r\n\r\nAluminum is a very good reducing agent and may replace other reducing agents in the isolation of certain metals from their oxides. Although more expensive than reduction by carbon, aluminum is important in the isolation of Mo, W, and Cr from their oxides.\r\n<h2 data-type=\"title\">Group 14<\/h2>\r\nThe metallic members of group 14 are tin, lead, and flerovium. Carbon is a typical nonmetal. The remaining elements of the group, silicon and germanium, are examples of semimetals or metalloids. Tin and lead form the stable divalent cations, Sn<sup>2+<\/sup> and Pb<sup>2+<\/sup>, with oxidation states two below the group oxidation state of 4+. The stability of this oxidation state is a consequence of the inert pair effect. Tin and lead also form covalent compounds with a formal 4+-oxidation state. For example, SnCl<sub>4<\/sub> and PbCl<sub>4<\/sub> are low-boiling covalent liquids.\r\n\r\n[caption id=\"attachment_2324\" align=\"aligncenter\" width=\"975\"]<img class=\"size-full wp-image-2324\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212459\/CNX_Chem_18_01_TinChlorid1.jpg\" alt=\"Two photos are shown and labeled \u201ca\u201d and \u201cb.\u201d Photo a shows a watch glass holding a fine, white powder. Photo b shows a sealed glass vial holding a clear, colorless liquid.\" width=\"975\" height=\"432\" \/> Figure\u00a08. (a) Tin(II) chloride is an ionic solid; (b) tin(IV) chloride is a covalent liquid.[\/caption]\r\n\r\nTin reacts readily with nonmetals and acids to form tin(II) compounds (indicating that it is more easily oxidized than hydrogen) and with nonmetals to form either tin(II) or tin(IV) compounds (shown in Figure\u00a08), depending on the stoichiometry and reaction conditions. Lead is less reactive. It is only slightly easier to oxidize than hydrogen, and oxidation normally requires a hot concentrated acid.\r\n\r\nMany of these elements exist as allotropes. <b>Allotropes<\/b> are two or more forms of the same element in the same physical state with different chemical and physical properties. There are two common allotropes of tin. These allotropes are grey (brittle) tin and white tin. As with other allotropes, the difference between these forms of tin is in the arrangement of the atoms. White tin is stable above 13.2 \u00b0C and is malleable like other metals. At low temperatures, gray tin is the more stable form. Gray tin is brittle and tends to break down to a powder. Consequently, articles made of tin will disintegrate in cold weather, particularly if the cold spell is lengthy. The change progresses slowly from the spot of origin, and the gray tin that is first formed catalyzes further change. In a way, this effect is similar to the spread of an infection in a plant or animal body, leading people to call this process tin disease or tin pest.\r\n\r\nThe principal use of tin is in the coating of steel to form tin plate-sheet iron, which constitutes the tin in tin cans. Important tin alloys are bronze (Cu and Sn) and solder (Sn and Pb). Lead is important in the lead storage batteries in automobiles.\r\n<h2 data-type=\"title\">Group 15<\/h2>\r\n<b>Bismuth<\/b>, the heaviest member of group 15, is a less reactive metal than the other representative metals. It readily gives up three of its five valence electrons to active nonmetals to form the tri-positive ion, Bi<sup>3+<\/sup>. It forms compounds with the group oxidation state of 5+ only when treated with strong oxidizing agents. The stability of the 3+-oxidation state is another example of the inert pair effect.\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Key Concepts and Summary<\/h3>\r\nThis section focuses on the periodicity of the representative elements. These are the elements where the electrons are entering the <em>s<\/em> and <em>p<\/em> orbitals. The representative elements occur in groups 1, 2, and 12\u201318. These elements are representative metals, metalloids, and nonmetals. The alkali metals (group 1) are very reactive, readily form ions with a charge of 1+ to form ionic compounds that are usually soluble in water, and react vigorously with water to form hydrogen gas and a basic solution of the metal hydroxide. The outermost electrons of the alkaline earth metals (group 2) are more difficult to remove than the outer electron of the alkali metals, leading to the group 2 metals being less reactive than those in group 1. These elements easily form compounds in which the metals exhibit an oxidation state of 2+. Zinc, cadmium, and mercury (group 12) commonly exhibit the group oxidation state of 2+ (although mercury also exhibits an oxidation state of 1+ in compounds that contain [latex]{\\text{Hg}}_{2}{}^{2+}[\/latex] ). Aluminum, gallium, indium, and thallium (group 13) are easier to oxidize than is hydrogen. Aluminum, gallium, and indium occur with an oxidation state 3+ (however, thallium also commonly occurs as the Tl<sup>+<\/sup> ion). Tin and lead form stable divalent cations and covalent compounds in which the metals exhibit the 4+-oxidation state.\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Exercises<\/h3>\r\n<ol>\r\n \t<li id=\"fs-idp133644368\">How do alkali metals differ from alkaline earth metals in atomic structure and general properties?<\/li>\r\n \t<li>Why does the reactivity of the alkali metals decrease from cesium to lithium?<\/li>\r\n \t<li>Predict the formulas for the nine compounds that may form when each species in column 1 of the table below\u00a0reacts with each species in column 2.\r\n<table>\r\n<thead>\r\n<tr valign=\"top\">\r\n<th>1<\/th>\r\n<th>2<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr valign=\"top\">\r\n<td>Na<\/td>\r\n<td>I<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td>Sr<\/td>\r\n<td>Se<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td>Al<\/td>\r\n<td>O<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/li>\r\n \t<li>Predict the best choice in each of the following. You may wish to review the chapter on electronic structure for relevant examples.\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>the most metallic of the elements Al, Be, and Ba<\/li>\r\n \t<li>the most covalent of the compounds NaCl, CaCl<sub>2<\/sub>, and BeCl<sub>2<\/sub><\/li>\r\n \t<li>the lowest first ionization energy among the elements Rb, K, and Li<\/li>\r\n \t<li>the smallest among Al, Al<sup>+<\/sup>, and Al<sup>3+<\/sup><\/li>\r\n \t<li>the largest among Cs<sup>+<\/sup>, Ba<sup>2+<\/sup>, and Xe<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Sodium chloride and strontium chloride are both white solids. How could you distinguish one from the other?<\/li>\r\n \t<li>The reaction of quicklime, CaO, with water produces slaked lime, Ca(OH)<sub>2<\/sub>, which is widely used in the construction industry to make mortar and plaster. The reaction of quicklime and water is highly exothermic:[latex]\\text{CaO}\\left(s\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{Ca}{\\left(\\text{OH}\\right)}_{2}\\left(s\\right)[\/latex][latex]\\Delta H=-\\text{350 kJ}{\\text{mol}}^{-\\text{1}}[\/latex]\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>What is the enthalpy of reaction per gram of quicklime that reacts?<\/li>\r\n \t<li>How much heat, in kilojoules, is associated with the production of 1 ton of slaked lime?<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Write a balanced equation for the reaction of elemental strontium with each of the following:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>oxygen<\/li>\r\n \t<li>hydrogen bromide<\/li>\r\n \t<li>hydrogen<\/li>\r\n \t<li>phosphorus<\/li>\r\n \t<li>water<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>How many moles of ionic species are present in 1.0 L of a solution marked 1.0 <em>M<\/em> mercury(I) nitrate?<\/li>\r\n \t<li>What is the mass of fish, in kilograms, that one would have to consume to obtain a fatal dose of mercury, if the fish contains 30 parts per million of mercury by weight? (Assume that all the mercury from the fish ends up as mercury(II) chloride in the body and that a fatal dose is 0.20 g of HgCl<sub>2<\/sub>.) How many pounds of fish is this?<\/li>\r\n \t<li>The elements sodium, aluminum, and chlorine are in the same period.\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>Which has the greatest electronegativity?<\/li>\r\n \t<li>Which of the atoms is smallest?<\/li>\r\n \t<li>Write the Lewis structure for the simplest covalent compound that can form between aluminum and chlorine.<\/li>\r\n \t<li>Will the oxide of each element be acidic, basic, or amphoteric?<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Does metallic tin react with HCl?<\/li>\r\n \t<li>What is tin pest, also known as tin disease?<\/li>\r\n \t<li>Compare the nature of the bonds in PbCl<sub>2<\/sub> to that of the bonds in PbCl<sub>4<\/sub>.<\/li>\r\n \t<li>Is the reaction of rubidium with water more or less vigorous than that of sodium? How does the rate of reaction of magnesium compare?<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"331931\"]Show Selected Answers[\/reveal-answer]\r\n[hidden-answer a=\"331931\"]\r\n\r\n1.\u00a0The alkali metals all have a single <em>s<\/em> electron in their outermost shell. In contrast, the alkaline earth metals have a completed <em>s<\/em> subshell in their outermost shell. In general, the alkali metals react faster and are more reactive than the corresponding alkaline earth metals in the same period.\r\n\r\n3. The formulas are as follows:\r\n\r\n[latex]\\begin{array}{l}\\text{Na}+{\\text{I}}_{2}\\rightarrow\\text{2NaI}\\\\ \\text{2Na}+\\text{Se}\\rightarrow{\\text{Na}}_{2}\\text{Se}\\\\ \\text{2Na}+{\\text{O}}_{2}\\rightarrow{\\text{Na}}_{2}{\\text{O}}_{2}\\end{array}[\/latex]\r\n\r\n[latex]\\begin{array}{l}\\text{Sr}+{\\text{I}}_{2}\\rightarrow{\\text{SrI}}_{2}\\\\ \\text{Sr}+\\text{Se}\\rightarrow\\text{SeSe}\\\\ \\text{2Sr}+{\\text{O}}_{2}\\rightarrow\\text{2SrO}\\end{array}[\/latex]\r\n\r\n[latex]\\begin{array}{l}\\text{2Al}+{\\text{3I}}_{2}\\rightarrow{\\text{2AlI}}_{3}\\\\ \\text{2Al}+\\text{3Se}\\rightarrow{\\text{Al}}_{2}{\\text{Se}}_{3}\\\\ \\text{4Al}+{\\text{3O}}_{2}\\rightarrow{\\text{2Al}}_{2}{\\text{O}}_{3}\\end{array}[\/latex]\r\n\r\n5.\u00a0The possible ways of distinguishing between the two include infrared spectroscopy by comparison of known compounds, a flame test that gives the characteristic yellow color for sodium (strontium has a red flame), or comparison of their solubilities in water. At 20 \u00b0C, NaCl dissolves to the extent of [latex]\\frac{\\text{35.7 g}}{\\text{100 mL}}[\/latex] compared with [latex]\\frac{\\text{53.8 g}}{\\text{100 mL}}[\/latex] for SrCl<sub>2<\/sub>. Heating to 100 \\textdegree C provides an easy test, since the solubility of NaCl is [latex]\\frac{\\text{39.12 g}}{\\text{100 mL}},[\/latex] but that of SrCl<sub>2<\/sub> is [latex]\\frac{\\text{100.8 g}}{\\text{100 mL}}.[\/latex] Density determination on a solid is sometimes difficult, but there is enough difference (2.165 g\/mL NaCl and 3.052 g\/mL SrCl<sub>2<\/sub>) that this method would be viable and perhaps the easiest and least expensive test to perform.\r\n\r\n7. The balanced equations are as follows:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[latex]\\text{2Sr}\\left(s\\right)+{\\text{O}}_{2}\\left(g\\right)\\rightarrow\\text{2SrO}\\left(s\\right)[\/latex]<\/li>\r\n \t<li>[latex]\\text{Sr}\\left(s\\right)+\\text{2HBr}\\left(g\\right)\\rightarrow{\\text{SrBr}}_{2}\\left(s\\right)+{\\text{H}}_{2}\\left(g\\right)[\/latex]<\/li>\r\n \t<li>[latex]\\text{Sr}\\left(s\\right)+{\\text{H}}_{2}\\left(g\\right)\\rightarrow{\\text{SrH}}_{2}\\left(s\\right)[\/latex]<\/li>\r\n \t<li>[latex]\\text{6Sr}\\left(s\\right)+{\\text{P}}_{4}\\left(s\\right)\\rightarrow{\\text{2Sr}}_{3}{\\text{P}}_{2}\\left(s\\right)[\/latex]<\/li>\r\n \t<li>[latex]\\text{Sr}\\left(s\\right)+{\\text{2H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{Sr}{\\left(\\text{OH}\\right)}_{2}\\left(aq\\right)+{\\text{H}}_{2}\\left(g\\right)[\/latex]<\/li>\r\n<\/ol>\r\n9.\u00a0The mass of Hg in 0.20 g HgCl<sub>2<\/sub> is [latex]0.20\\cancel{{\\text{g HgCl}}_{2}}\\times \\frac{\\text{200.59 g Hg}}{271.50\\cancel{{\\text{g HgCl}}_{2}}}=\\text{0.15 g Hg}.[\/latex]\r\n\r\nThen [latex]\\frac{30}{1\\times {10}^{6}}\\times \\text{mass of fish}=\\text{0.15 g Hg}.[\/latex] Mass of fish = 5.0 \u00d7 10<sup>3<\/sup> g. To convert to units of pounds, [latex]5.0\\times {10}^{3}\\cancel{\\text{g}}\\times \\frac{\\text{1 lb}}{453.6\\cancel{\\text{g}}}=\\text{11 lb}[\/latex]\r\n\r\n11.\u00a0Yes, tin reacts with hydrochloric acid to produce hydrogen gas. This ability can be determined from the standard reduction potentials in <a class=\"target-chapter\" href=\".\/chapter\/standard-electrode-half-cell-potentials\/\" target=\"_blank\">Standard Electrode (Half-Cell) Potentials<\/a>.\r\n\r\n13.\u00a0In PbCl<sub>2<\/sub>, the bonding is ionic, as indicated by its melting point of 501 \u00b0C. In PbCl<sub>4<\/sub>, the bonding is covalent, as evidenced by it being an unstable liquid at room temperature.\r\n\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<h2>Glossary<\/h2>\r\n<b>alkaline earth metal: <\/b>any of the metals (beryllium, magnesium, calcium, strontium, barium, and radium) occupying group 2 of the periodic table; they are reactive, divalent metals that form basic oxides\r\n\r\n<b>allotropes: <\/b>two or more forms of the same element, in the same physical state, with different chemical structures\r\n\r\n<b>bismuth: <\/b>heaviest member of group 15; a less reactive metal than other representative metals\r\n\r\n<b>metal: <\/b>atoms of the metallic elements of groups 1, 2, 12, 13, 14, 15, and 16, which form ionic compounds by losing electrons from their outer <em>s<\/em> or <em>p<\/em> orbitals\r\n\r\n<b>metalloid: <\/b>element that has properties that are between those of metals and nonmetals; these elements are typically semiconductors\r\n\r\n<b>passivation: <\/b>metals with a protective nonreactive film of oxide or other compound that creates a barrier for chemical reactions; physical or chemical removal of the passivating film allows the metals to demonstrate their expected chemical reactivity\r\n\r\n<b>representative element: <\/b>element where the <em>s<\/em> and <em>p<\/em> orbitals are filling\r\n\r\n<b>representative metal: <\/b>metal among the representative elements\r\n\r\n<b>salt: <\/b>ionic compound consisting of cations and anions","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<p>By the end of this module, you will be able to:<\/p>\n<ul>\n<li>Classify elements<\/li>\n<li>Make predictions about the periodicity properties of the representative elements<\/li>\n<\/ul>\n<\/div>\n<p>We begin this section by examining the behaviors of representative metals in relation to their positions in the periodic table. The primary focus of this section will be the application of periodicity to the representative metals.<\/p>\n<p>It is possible to divide elements into groups according to their electron configurations. The <b>representative elements<\/b> are elements where the <em>s<\/em> and <em>p<\/em> orbitals are filling. The transition elements are elements where the <em>d<\/em> orbitals (groups 3\u201311 on the periodic table) are filling, and the inner transition metals are the elements where the <em>f<\/em> orbitals are filling. The <em>d<\/em> orbitals fill with the elements in group 11; therefore, the elements in group 12 qualify as representative elements because the last electron enters an <em>s<\/em> orbital. Metals among the representative elements are the <b>representative metals<\/b>. Metallic character results from an element\u2019s ability to lose its outer valence electrons and results in high thermal and electrical conductivity, among other physical and chemical properties. There are 20 nonradioactive representative metals in groups 1, 2, 3, 12, 13, 14, and 15 of the periodic table (the elements shaded in yellow in Figure\u00a01). The radioactive elements copernicium, flerovium, polonium, and livermorium are also metals but are beyond the scope of this chapter.<\/p>\n<p>In addition to the representative metals, some of the representative elements are metalloids. A <b>metalloid<\/b> is an element that has properties that are between those of metals and nonmetals; these elements are typically semiconductors.<\/p>\n<p>The remaining representative elements are nonmetals. Unlike <b>metals<\/b>, which typically form cations and ionic compounds (containing ionic bonds), nonmetals tend to form anions or molecular compounds. In general, the combination of a metal and a nonmetal produces a salt. A <b>salt<\/b> is an ionic compound consisting of cations and anions.<\/p>\n<div id=\"attachment_5038\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-5038\" class=\"size-large wp-image-5038\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/08\/23214511\/CNX_Chem_18_01_PeriodicPU3-1024x840.jpg\" alt=\"The Periodic Table\u00a0of Elements is shown. The 18 columns are labeled \u201cGroup\u201d and the 7 rows are labeled \u201cPeriod.\u201d Below the table to the right is a box labeled \u201cColor Code\u201d with different colors for representative metals, transition and inner transition metals, radioactive elements, metalloids, and nonmetals, as well as solids, liquids, and gases. Each element will be described in this order: atomic number; name; symbol; whether it is a representative metal, transition and inner transition metal, radioactive element, metalloid, or nonmetal; whether it is a solid, liquid, or gas; and atomic mass. Beginning at the top left of the table, or period 1, group 1, is a box containing \u201c1; hydrogen; H; nonmetal; gas; and 1.008.\u201d There is only one other element box in period 1, group 18, which contains \u201c2; helium; H e; nonmetal; gas; and 4.003.\u201d Period 2, group 1 contains \u201c3; lithium; L i; representative metal; solid; and 6.94\u201d Group 2 contains \u201c4; beryllium; B e; representative metal; solid; and 9.012.\u201d Groups 3 through 12 are skipped and group 13 contains \u201c5; boron; B; metalloid; solid; 10.81.\u201d Group 14 contains \u201c6; carbon; C; nonmetal; solid; and 12.01.\u201d Group 15 contains \u201c7; nitrogen; N; nonmetal; gas; and 14.01.\u201d Group 16 contains \u201c8; oxygen; O; nonmetal; gas; and 16.00.\u201d Group 17 contains \u201c9; fluorine; F; nonmetal; gas; and 19.00.\u201d Group 18 contains \u201c10; neon; N e; nonmetal; gas; and 20.18.\u201d Period 3, group 1 contains \u201c11; sodium; N a; representative metal; solid; and 22.99.\u201d Group 2 contains \u201c12; magnesium; M g; representative metal; solid; and 24.31.\u201d Groups 3 through 12 are skipped again in period 3 and group 13 contains \u201c13; aluminum; A l; representative metal; solid; and 26.98.\u201d Group 14 contains \u201c14; silicon; S i; metalloid; solid; and 28.09.\u201d Group 15 contains \u201c15; phosphorous; P; nonmetal; solid; and 30.97.\u201d Group 16 contains \u201c16; sulfur; S; nonmetal; solid; and 32.06.\u201d Group 17 contains \u201c17; chlorine; C l; nonmetal; gas; and 35.45.\u201d Group 18 contains \u201c18; argon; A r; nonmetal; gas; and 39.95.\u201d Period 4, group 1 contains \u201c19; potassium; K; representative metal; solid; and 39.10.\u201d Group 2 contains \u201c20; calcium; C a; representative metal; solid; and 40.08.\u201d Group 3 contains \u201c21; scandium; S c; transition and inner transition metal; solid; and 44.96.\u201d Group 4 contains \u201c22; titanium; T i; transition and inner transition metal; solid; and 47.87.\u201d Group 5 contains \u201c23; vanadium; V; transition and inner transition metal; solid; and 50.94.\u201d Group 6 contains \u201c24; chromium; C r; transition and inner transition metal; solid; and 52.00.\u201d Group 7 contains \u201c25; manganese; M n; transition and inner transition metal; solid; and 54.94.\u201d Group 8 contains \u201c26; iron; F e; transition and inner transition metal; solid; and 55.85.\u201d Group 9 contains \u201c27; cobalt; C o; transition and inner transition metal; solid; and 58.93.\u201d Group 10 contains \u201c28; nickel; N i; transition and inner transition metal; solid; and 58.69.\u201d Group 11 contains \u201c29; copper; C u; transition and inner transition metal; solid; and 63.55.\u201d Group 12 contains \u201c30; zinc; Z n; transition and inner transition metal; solid; and 65.38.\u201d Group 13 contains \u201c31; gallium; G a; representative metal; solid; and 69.72.\u201d Group 14 contains \u201c32; germanium; G e; metalloid; solid; and 72.63.\u201d Group 15 contains \u201c33; arsenic; A s; metalloid; solid; and 74.92.\u201d Group 16 contains \u201c34; selenium; S e; nonmetal; solid; and 78.97.\u201d Group 17 contains \u201c35; bromine; B r; nonmetal; liquid; and 79.90.\u201d Group 18 contains \u201c36; krypton; K r; nonmetal; gas; and 83.80.\u201d Period 5, group 1 contains \u201c37; rubidium; R b; representative metal; solid; and 85.47.\u201d Group 2 contains \u201c38; strontium; S r; representative metal; solid; and 87.62.\u201d Group 3 contains \u201c39; yttrium; Y; transition and inner transition metal; solid; and 88.91.\u201d Group 4 contains \u201c40; zirconium; Z r; transition and inner transition metal; solid; and 91.22.\u201d Group 5 contains \u201c41; niobium; N b; transition and inner transition metal; solid; and 92.91.\u201d Group 6 contains \u201c42; molybdenum; M o; transition and inner transition metal; solid; and 95.95.\u201d Group 7 contains \u201c43; technetium; T c; radioactive element; solid; and 97.\u201d Group 8 contains \u201c44; ruthenium; R u; transition and inner transition metal; solid; and 101.1.\u201d Group 9 contains \u201c45; rhodium; R h; transition and inner transition metal; solid; and 102.9.\u201d Group 10 contains \u201c46; palladium; P d; transition and inner transition metal; solid; and 106.4.\u201d Group 11 contains \u201c47; silver; A g; transition and inner transition metal; solid; and 107.9.\u201d Group 12 contains \u201c48; cadmium; C d; transition and inner transition metal; solid; and 112.4.\u201d Group 13 contains \u201c49; indium; I n; representative metal; solid; and 114.8.\u201d Group 14 contains \u201c50; tin; S n; representative metal; solid; and 118.7.\u201d Group 15 contains \u201c51; antimony; S b; metalloid; solid; and 121.8.\u201d Group 16 contains \u201c52; tellurium; T e; metalloid; solid; and 127.6.\u201d Group 17 contains \u201c53; iodine; I; nonmetal; solid; and 126.9.\u201d Group 18 contains \u201c54; xenon; X e; nonmetal; gas; and 131.3.\u201d Period 6, group 1 contains \u201c55; cesium; C s; representative metal; solid; and 132.9.\u201d Group 2 contains \u201c56; barium; B a; representative metal; solid; and 137.3.\u201d Group 3 breaks the pattern. The box has a large arrow pointing to a row of elements below the table with atomic numbers ranging from 57-71. In sequential order by atomic number, the first box in this row contains \u201c57; lanthanum; L a; representative metal; solid; and 138.9.\u201d To its right, the next is \u201c58; cerium; C e; representative metal; solid; and 140.1.\u201d Next is \u201c59; praseodymium; P r; representative metal; solid; and 140.9.\u201d Next is \u201c60; neodymium; N d; representative metal; solid; and 144.2.\u201d Next is \u201c61; promethium; P m; radioactive element; solid; and 145.\u201d Next is \u201c62; samarium; S m; representative metal; solid; and 150.4.\u201d Next is \u201c63; europium; E u; representative metal; solid; and 152.0.\u201d Next is \u201c64; gadolinium; G d; representative metal; solid; and 157.3.\u201d Next is \u201c65; terbium; T b; representative metal; solid; and 158.9.\u201d Next is \u201c66; dysprosium; D y; representative metal; solid; and 162.5.\u201d Next is \u201c67; holmium; H o; representative metal; solid; and 164.9.\u201d Next is \u201c68; erbium; E r; representative metal; solid; and 167.3.\u201d Next is \u201c69; thulium; T m; representative metal; solid; and 168.9.\u201d Next is \u201c70; ytterbium; Y b; representative metal; solid; and 173.1.\u201d The last in this special row is \u201c71; lutetium; L u; representative metal; solid; and 175.0.\u201d Continuing in period 6, group 4 contains \u201c72; hafnium; H f; transition and inner transition metal; solid; and 178.5.\u201d Group 5 contains \u201c73; tantalum; T a; transition and inner transition metal; solid; and 180.9.\u201d Group 6 contains \u201c74; tungsten; W; transition and inner transition metal; solid; and 183.8.\u201d Group 7 contains \u201c75; rhenium; R e; transition and inner transition metal; solid; and 186.2.\u201d Group 8 contains \u201c76; osmium; O s; transition and inner transition metal; solid; and 190.2.\u201d Group 9 contains \u201c77; iridium; I r; transition and inner transition metal; solid; and 192.2.\u201d Group 10 contains \u201c78; platinum; P t; transition and inner transition metal; solid; and 195.1.\u201d Group 11 contains \u201c79; gold; A u; transition and inner transition metal; solid; and 197.0.\u201d Group 12 contains \u201c80; mercury; H g; transition and inner transition metal; liquid; and 200.6.\u201d Group 13 contains \u201c81; thallium; T l; representative metal; solid; and 204.4.\u201d Group 14 contains \u201c82; lead; P b; representative metal; solid; and 207.2.\u201d Group 15 contains \u201c83; bismuth; B i; representative metal; solid; and 209.0.\u201d Group 16 contains \u201c84; polonium; P o; radioactive element; solid; and 209.\u201d Group 17 contains \u201c85; astatine; A t; radioactive element; solid; and 210.\u201d Group 18 contains \u201c86; radon; R n; radioactive element; gas; and 222.\u201d Period 7, group 1 contains \u201c87; francium; F r; radioactive element; solid; and 223.\u201d Group 2 contains \u201c88; radium; R a; radioactive element; solid; and 226.\u201d Group 3 breaks the pattern much like what occurs in period 6. A large arrow points from the box in period 7, group 3 to a special row containing the elements with atomic numbers ranging from 89-103, just below the row which contains atomic numbers 57-71. In sequential order by atomic number, the first box in this row contains \u201c89; actinium; A c; radioactive element; solid; and 227.\u201d To its right, the next is \u201c90; thorium; T h; radioactive element; solid; and 232.0.\u201d Next is \u201c91; protactinium; P a; radioactive element; solid; and 231.0.\u201d Next is \u201c92; uranium; U; radioactive element; solid; and 238.0.\u201d Next is \u201c93; neptunium; N p; radioactive element; solid; and N p.\u201d Next is \u201c94; plutonium; P u; radioactive element; solid; and 244.\u201d Next is \u201c95; americium; A m; radioactive element; solid; and 243.\u201d Next is \u201c96; curium; C m; radioactive element; solid; and 247.\u201d Next is \u201c97; berkelium; B k; radioactive element; solid; and 247.\u201d Next is \u201c98; californium; C f; radioactive element; solid; and 251.\u201d Next is \u201c99; einsteinium; E s; radioactive element; solid; and 252.\u201d Next is \u201c100; fermium; F m; radioactive element; solid; and 257.\u201d Next is \u201c101; mendelevium; M d; radioactive element; solid; and 258.\u201d Next is \u201c102; nobelium; N o; radioactive element; solid; and 259.\u201d The last in this special row is \u201c103; lawrencium; L r; radioactive element; solid; and 262.\u201d Continuing in period 7, group 4 contains \u201c104; rutherfordium; R f; transition and inner transition metal; solid; and 267.\u201d Group 5 contains \u201c105; dubnium; D b; transition and inner transition metal; solid; and 270.\u201d Group 6 contains \u201c106; seaborgium; S g; transition and inner transition metal; solid; and 271.\u201d Group 7 contains \u201c107; bohrium; B h; transition and inner transition metal; solid; and 270.\u201d Group 8 contains \u201c108; hassium; H s; transition and inner transition metal; solid; and 277.\u201d Group 9 contains \u201c109; meitnerium; M t; radioactive element; solid; and 276.\u201d Group 10 contains \u201c110; darmstadtium; D s; radioactive element; solid; and 281.\u201d Group 11 contains \u201c111; roentgenium; R g; radioactive element; solid; and 282.\u201d Group 12 contains \u201c112; copernicium; C n; radioactive element; liquid; and 285.\u201d Group 13 contains \u201c113; ununtrium; U u t; radioactive element; solid; and 285.\u201d Group 14 contains \u201c114; flerovium; F l; radioactive element; solid; and 289.\u201d Group 15 contains \u201c115; ununpentium; U u p; radioactive element; solid; and 288.\u201d Group 16 contains \u201c116; livermorium; L v; radioactive element; solid; and 293.\u201d Group 17 contains \u201c117; ununseptium; U u s; radioactive; solid; and 294.\u201d Group 18 contains \u201c118; ununoctium; U u o; radioactive element; solid; and 294.\u201d\" width=\"1024\" height=\"840\" \/><\/p>\n<p id=\"caption-attachment-5038\" class=\"wp-caption-text\">Figure\u00a01. The location of the representative metals is shown in the periodic table. Nonmetals are shown in green, metalloids in purple, and the transition metals and inner transition metals in yellow.<\/p>\n<\/div>\n<p>Most of the representative metals do not occur naturally in an uncombined state because they readily react with water and oxygen in the air. However, it is possible to isolate elemental beryllium, magnesium, zinc, cadmium, mercury, aluminum, tin, and lead from their naturally occurring minerals and use them because they react very slowly with air. Part of the reason why these elements react slowly is that these elements react with air to form a protective coating. The formation of this protective coating is <b>passivation<\/b>. The coating is a nonreactive film of oxide or some other compound. Elemental magnesium, aluminum, zinc, and tin are important in the fabrication of many familiar items, including wire, cookware, foil, and many household and personal objects. Although beryllium, cadmium, mercury, and lead are readily available, there are limitations in their use because of their toxicity.<\/p>\n<h2 data-type=\"title\">Group 1: The Alkali Metals<\/h2>\n<p>The alkali metals lithium, sodium, potassium, rubidium, cesium, and francium constitute group 1 of the periodic table. Although hydrogen is in group 1 (and also in group 17), it is a nonmetal and deserves separate consideration later in this chapter. The name alkali metal is in reference to the fact that these metals and their oxides react with water to form very basic (alkaline) solutions.<\/p>\n<div id=\"attachment_2317\" style=\"width: 410px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2317\" class=\"wp-image-2317\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212450\/CNX_Chem_18_01_LithiumRx1.jpg\" alt=\"A glass container that is half filled with a colorless liquid is shown. Blocks of a shiny silver solid float on top of the liquid in the container.\" width=\"400\" height=\"222\" \/><\/p>\n<p id=\"caption-attachment-2317\" class=\"wp-caption-text\">Figure\u00a02. Lithium floats in paraffin oil because its density is less than the density of paraffin oil.<\/p>\n<\/div>\n<p>The properties of the alkali metals are similar to each other as expected for elements in the same family. The alkali metals have the largest atomic radii and the lowest first ionization energy in their periods. This combination makes it very easy to remove the single electron in the outermost (valence) shell of each. The easy loss of this valence electron means that these metals readily form stable cations with a charge of 1+. Their reactivity increases with increasing atomic number due to the ease of losing the lone valence electron (decreasing ionization energy). Since oxidation is so easy, the reverse, reduction, is difficult, which explains why it is hard to isolate the elements. The solid alkali metals are very soft; lithium, shown in Figure\u00a02, has the lowest density of any metal (0.5 g\/cm<sup>3<\/sup>).<\/p>\n<p>The alkali metals all react vigorously with water to form hydrogen gas and a basic solution of the metal hydroxide. This means they are easier to oxidize than is hydrogen. As an example, the reaction of lithium with water is:<\/p>\n<p style=\"text-align: center;\">[latex]\\text{2Li}\\left(s\\right)+{\\text{2H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{2LiOH}\\left(aq\\right)+{\\text{H}}_{2}\\left(g\\right)[\/latex]<\/p>\n<p>Alkali metals react directly with all the nonmetals (except the noble gases) to yield binary ionic compounds containing 1+ metal ions. These metals are so reactive that it is necessary to avoid contact with both moisture and oxygen in the air. Therefore, they are stored in sealed containers under mineral oil, as shown in Figure\u00a03, to prevent contact with air and moisture. The pure metals never exist free (uncombined) in nature due to their high reactivity. In addition, this high reactivity makes it necessary to prepare the metals by electrolysis of alkali metal compounds.<\/p>\n<div id=\"attachment_5901\" style=\"width: 559px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-5901\" class=\"wp-image-5901\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/218\/2016\/10\/24205154\/CNX_Chem_18_01_AlkMetStor1-1024x633.jpg\" alt=\"A sealed, tube-like glass container is shown. The container is partially filled with a colorless liquid and contains two metallic spheres.\" width=\"549\" height=\"340\" \/><\/p>\n<p id=\"caption-attachment-5901\" class=\"wp-caption-text\">Figure\u00a03. To prevent contact with air and water, potassium for laboratory use comes as sticks or beads stored under kerosene or mineral oil, or in sealed containers. (credit: http:\/\/images-of-elements.com\/potassium.php)<\/p>\n<\/div>\n<div class=\"textbox\">\n<p>This video demonstrates the reactions of the alkali metals with water.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Reaction of Lithium and Water\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/Vxqe_ZOwsHs?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/div>\n<div id=\"attachment_2319\" style=\"width: 210px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2319\" class=\"wp-image-2319\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212453\/CNX_Chem_18_01_NaFlame1.jpg\" alt=\"A photo of a lit Bunsen burner is shown. A wooden splint is placed in the flame, and a yellow flame is produced.\" width=\"200\" height=\"594\" \/><\/p>\n<p id=\"caption-attachment-2319\" class=\"wp-caption-text\">Figure\u00a04. Dipping a wire into a solution of a sodium salt and then heating the wire causes emission of a bright yellow light, characteristic of sodium.<\/p>\n<\/div>\n<p>Unlike many other metals, the reactivity and softness of the alkali metals make these metals unsuitable for structural applications. However, there are applications where the reactivity of the alkali metals is an advantage. For example, the production of metals such as titanium and zirconium relies, in part, on the ability of sodium to reduce compounds of these metals. The manufacture of many organic compounds, including certain dyes, drugs, and perfumes, utilizes reduction by lithium or sodium.<\/p>\n<p>Sodium and its compounds impart a bright yellow color to a flame, as seen in Figure\u00a04. Passing an electrical discharge through sodium vapor also produces this color. In both cases, this is an example of an emission spectrum as discussed in the chapter on electronic structure. Streetlights sometime employ sodium vapor lights because the sodium vapor penetrates fog better than most other light. This is because the fog does not scatter yellow light as much as it scatters white light. The other alkali metals and their salts also impart color to a flame. Lithium creates a bright, crimson color, whereas the others create a pale, violet color.<\/p>\n<h2 data-type=\"title\">Group 2: The Alkaline Earth Metals<\/h2>\n<p>The <b>alkaline earth metals<\/b> (beryllium, magnesium, calcium, strontium, barium, and radium) constitute group 2 of the periodic table. The name alkaline metal comes from the fact that the oxides of the heavier members of the group react with water to form alkaline solutions. The nuclear charge increases when going from group 1 to group 2. Because of this charge increase, the atoms of the alkaline earth metals are smaller and have higher first ionization energies than the alkali metals within the same period. The higher ionization energy makes the alkaline earth metals less reactive than the alkali metals; however, they are still very reactive elements. Their reactivity increases, as expected, with increasing size and decreasing ionization energy. In chemical reactions, these metals readily lose both valence electrons to form compounds in which they exhibit an oxidation state of 2+. Due to their high reactivity, it is common to produce the alkaline earth metals, like the alkali metals, by electrolysis. Even though the ionization energies are low, the two metals with the highest ionization energies (beryllium and magnesium) do form compounds that exhibit some covalent characters. Like the alkali metals, the heavier alkaline earth metals impart color to a flame. As in the case of the alkali metals, this is part of the emission spectrum of these elements. Calcium and strontium produce shades of red, whereas barium produces a green color.<\/p>\n<p>Magnesium is a silver-white metal that is malleable and ductile at high temperatures. Passivation decreases the reactivity of magnesium metal. Upon exposure to air, a tightly adhering layer of magnesium oxycarbonate forms on the surface of the metal and inhibits further reaction. (The carbonate comes from the reaction of carbon dioxide in the atmosphere.) Magnesium is the lightest of the widely used structural metals, which is why most magnesium production is for lightweight alloys.<\/p>\n<p>Magnesium (shown in Figure\u00a05), calcium, strontium, and barium react with water and air. At room temperature, barium shows the most vigorous reaction. The products of the reaction with water are hydrogen and the metal hydroxide. The formation of hydrogen gas indicates that the heavier alkaline earth metals are better reducing agents (more easily oxidized) than is hydrogen. As expected, these metals react with both acids and nonmetals to form ionic compounds. Unlike most salts of the alkali metals, many of the common salts of the alkaline earth metals are insoluble in water because of the high lattice energies of these compounds, containing a divalent metal ion.<\/p>\n<div id=\"attachment_2321\" style=\"width: 560px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2321\" class=\"wp-image-2321\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212455\/CNX_Chem_18_01_CalciWater1.jpg\" alt=\"Three glass containers with lids are shown in a photo. A plus sign is drawn between the first two containers and a right-facing arrow is drawn between the second and third containers. The left container holds a black granular solid while the center container holds a clear, colorless liquid. The right container holds a clear, pink liquid.\" width=\"550\" height=\"412\" \/><\/p>\n<p id=\"caption-attachment-2321\" class=\"wp-caption-text\">Figure\u00a05. From left to right: Mg(<em>s<\/em>), warm water at pH 7, and the resulting solution with a pH greater than 7, as indicated by the pink color of the phenolphthalein indicator. (credit: modification of work by Sahar Atwa)<\/p>\n<\/div>\n<p>The potent reducing power of hot magnesium is useful in preparing some metals from their oxides. Indeed, magnesium\u2019s affinity for oxygen is so great that burning magnesium reacts with carbon dioxide, producing elemental carbon:<\/p>\n<p style=\"text-align: center;\">[latex]\\text{2Mg}\\left(s\\right)+{\\text{CO}}_{2}\\left(g\\right)\\rightarrow\\text{2MgO}\\left(s\\right)+\\text{C}\\left(s\\right)[\/latex]<\/p>\n<p>For this reason, a CO<sub>2<\/sub> fire extinguisher will not extinguish a magnesium fire. Additionally, the brilliant white light emitted by burning magnesium makes it useful in flares and fireworks.<\/p>\n<h2 data-type=\"title\">Group 12<\/h2>\n<div id=\"attachment_2322\" style=\"width: 310px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2322\" class=\"wp-image-2322\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212456\/CNX_Chem_18_01_ZincHCl1.jpg\" alt=\"A glass tube holding a metallic solid in a colorless liquid is shown laying on a black background with white lettering.\" width=\"300\" height=\"418\" \/><\/p>\n<p id=\"caption-attachment-2322\" class=\"wp-caption-text\">Figure\u00a06. Zinc is an active transition metal. It dissolves in hydrochloric acid, forming a solution of colorless Zn<sup>2+<\/sup> ions, Cl<sup>\u2212<\/sup> ions, and hydrogen gas.<\/p>\n<\/div>\n<p>The elements in group 12 are not transition elements because the last electron added is not a <em>d<\/em> electron, but an <em>s<\/em> electron. Since the last electron added is an <em>s<\/em> electron, these elements qualify as representative metals, or post-transition metals. The group 12 elements behave more like the alkaline earth metals than transition metals. Group 12 contains the four elements zinc, cadmium, mercury, and copernicium. Each of these elements has two electrons in its outer shell (<em>ns<\/em><sup>2<\/sup>). When atoms of these metals form cations with a charge of 2+, where the two outer electrons are lost, they have pseudo-noble gas electron configurations. Mercury is sometimes an exception because it also exhibits an oxidation state of 1+ in compounds that contain a diatomic [latex]{\\text{Hg}}_{2}{}^{2+}[\/latex] ion. In their elemental forms and in compounds, cadmium and mercury are both toxic.<\/p>\n<p>Zinc is the most reactive in group 12, and mercury is the least reactive. (This is the reverse of the reactivity trend of the metals of groups 1 and 2, in which reactivity increases down a group. The increase in reactivity with increasing atomic number only occurs for the metals in groups 1 and 2.) The decreasing reactivity is due to the formation of ions with a pseudo-noble gas configuration and to other factors that are beyond the scope of this discussion. The chemical behaviors of zinc and cadmium are quite similar to each other but differ from that of mercury.<\/p>\n<p>Zinc and cadmium have lower reduction potentials than hydrogen, and, like the alkali metals and alkaline earth metals, they will produce hydrogen gas when they react with acids. The reaction of zinc with hydrochloric acid, shown in Figure\u00a06, is:<\/p>\n<p style=\"text-align: center;\">[latex]\\text{Zn}\\left(s\\right)+{\\text{2H}}_{3}{\\text{O}}^{+}\\left(aq\\right)+{\\text{2Cl}}^{-}\\left(aq\\right)\\rightarrow{\\text{H}}_{2}\\left(g\\right)+{\\text{Zn}}^{2+}\\left(aq\\right)+{\\text{2Cl}}^{-}\\left(aq\\right)+{\\text{2H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/p>\n<p>Zinc is a silvery metal that quickly tarnishes to a blue-gray appearance. This change in color is due to an adherent coating of a basic carbonate, Zn<sub>2<\/sub>(OH)<sub>2<\/sub>CO<sub>3<\/sub>, which passivates the metal to inhibit further corrosion. Dry cell and alkaline batteries contain a zinc anode. Brass (Cu and Zn) and some bronze (Cu, Sn, and sometimes Zn) are important zinc alloys. About half of zinc production serves to protect iron and other metals from corrosion. This protection may take the form of a sacrificial anode (also known as a galvanic anode, which is a means of providing cathodic protection for various metals) or as a thin coating on the protected metal. Galvanized steel is steel with a protective coating of zinc.<\/p>\n<div class=\"textbox shaded\">\n<h3 data-type=\"title\">Sacrificial Anodes<\/h3>\n<p>A sacrificial anode, or galvanic anode, is a means of providing cathodic protection of various metals. Cathodic protection refers to the prevention of corrosion by converting the corroding metal into a cathode. As a cathode, the metal resists corrosion, which is an oxidation process. Corrosion occurs at the sacrificial anode instead of at the cathode.<\/p>\n<p>The construction of such a system begins with the attachment of a more active metal (more negative reduction potential) to the metal needing protection. Attachment may be direct or via a wire. To complete the circuit, a <em>salt bridge<\/em> is necessary. This salt bridge is often seawater or ground water. Once the circuit is complete, oxidation (corrosion) occurs at the anode and not the cathode.<\/p>\n<p>The commonly used sacrificial anodes are magnesium, aluminum, and zinc. Magnesium has the most negative reduction potential of the three and serves best when the salt bridge is less efficient due to a low electrolyte concentration such as in freshwater. Zinc and aluminum work better in saltwater than does magnesium. Aluminum is lighter than zinc and has a higher capacity; however, an oxide coating may passivate the aluminum. In special cases, other materials are useful. For example, iron will protect copper.<\/p>\n<\/div>\n<p>Mercury is very different from zinc and cadmium. Mercury is the only metal that is liquid at 25 \u00b0C. Many metals dissolve in mercury, forming solutions called amalgams (see the feature on Amalgams), which are alloys of mercury with one or more other metals. Mercury, shown in Figure\u00a07, is a nonreactive element that is more difficult to oxidize than hydrogen. Thus, it does not displace hydrogen from acids; however, it will react with strong oxidizing acids, such as nitric acid:<\/p>\n<p style=\"text-align: center;\">[latex]\\text{Hg}\\left(l\\right)+\\text{HCl}\\left(aq\\right)\\rightarrow\\text{no reaction}[\/latex]<br \/>\n[latex]\\text{3Hg}\\left(l\\right)+{\\text{8HNO}}_{3}\\left(aq\\right)\\rightarrow\\text{3Hg}{\\left({\\text{NO}}_{3}\\right)}_{2}\\left(aq\\right)+{\\text{4H}}_{2}\\text{O}\\left(l\\right)+\\text{2NO}\\left(g\\right)[\/latex]<\/p>\n<p>The clear NO initially formed quickly undergoes further oxidation to the reddish brown NO<sub>2<\/sub>.<\/p>\n<div id=\"attachment_2323\" style=\"width: 561px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2323\" class=\"wp-image-2323\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212458\/CNX_Chem_18_01_MercuryRx1.jpg\" alt=\"Three test tubes are shown in a photo. The left tube contains a metallic liquid. The middle tube contains a metallic liquid under a layer of clear, colorless liquid. The third tube contains a whitish solid under a layer of yellowish liquid.\" width=\"551\" height=\"414\" \/><\/p>\n<p id=\"caption-attachment-2323\" class=\"wp-caption-text\">Figure\u00a07. From left to right: Hg(l), Hg<sup>+<\/sup> concentrated HCl, Hg<sup>+<\/sup> concentrated HNO<sub>3<\/sub>. (credit: Sahar Atwa)<\/p>\n<\/div>\n<p>Most mercury compounds decompose when heated. Most mercury compounds contain mercury with a 2+-oxidation state. When there is a large excess of mercury, it is possible to form compounds containing the [latex]{\\text{Hg}}_{2}^{2+}[\/latex] ion. All mercury compounds are toxic, and it is necessary to exercise great care in their synthesis.<\/p>\n<div class=\"textbox shaded\">\n<h3 data-type=\"title\">Amalgams<\/h3>\n<p>An amalgam is an alloy of mercury with one or more other metals. This is similar to considering steel to be an alloy of iron with other metals. Most metals will form an amalgam with mercury, with the main exceptions being iron, platinum, tungsten, and tantalum.<\/p>\n<p>Due to toxicity issues with mercury, there has been a significant decrease in the use of amalgams. Historically, amalgams were important in electrolytic cells and in the extraction of gold. Amalgams of the alkali metals still find use because they are strong reducing agents and easier to handle than the pure alkali metals.<\/p>\n<p>Prospectors had a problem when they found finely divided gold. They learned that adding mercury to their pans collected the gold into the mercury to form an amalgam for easier collection. Unfortunately, losses of small amounts of mercury over the years left many streams in California polluted with mercury.<\/p>\n<p>Dentists use amalgams containing silver and other metals to fill cavities. There are several reasons to use an amalgam including low cost, ease of manipulation, and longevity compared to alternate materials. Dental amalgams are approximately 50% mercury by weight, which, in recent years, has become a concern due to the toxicity of mercury.<\/p>\n<p>After reviewing the best available data, the Food and Drug Administration (FDA) considers amalgam-based fillings to be safe for adults and children over six years of age. Even with multiple fillings, the mercury levels in the patients remain far below the lowest levels associated with harm. Clinical studies have found no link between dental amalgams and health problems. Health issues may not be the same in cases of children under six or pregnant women. The FDA conclusions are in line with the opinions of the Environmental Protection Agency (EPA) and Centers for Disease Control (CDC). The only health consideration noted is that some people are allergic to the amalgam or one of its components.<\/p>\n<\/div>\n<h2 data-type=\"title\">Group 13<\/h2>\n<p>Group 13 contains the metalloid boron and the metals aluminum, gallium, indium, and thallium. The lightest element, boron, is semiconducting, and its binary compounds tend to be covalent and not ionic. The remaining elements of the group are metals, but their oxides and hydroxides change characters. The oxides and hydroxides of aluminum and gallium exhibit both acidic and basic behaviors. A substance, such as these two, that will react with both acids and bases is amphoteric. This characteristic illustrates the combination of nonmetallic and metallic behaviors of these two elements. Indium and thallium oxides and hydroxides exhibit only basic behavior, in accordance with the clearly metallic character of these two elements. The melting point of gallium is unusually low (about 30 \u00b0C) and will melt in your hand.<\/p>\n<p>Aluminum is amphoteric because it will react with both acids and bases. A typical reaction with an acid is:<\/p>\n<p style=\"text-align: center;\">[latex]\\text{2Al}\\left(s\\right)+\\text{6HCl}\\left(aq\\right)\\rightarrow{\\text{2AlCl}}_{3}\\left(aq\\right)+{\\text{3H}}_{2}\\left(g\\right)[\/latex]<\/p>\n<p>The products of the reaction of aluminum with a base depend upon the reaction conditions, with the following being one possibility:<\/p>\n<p style=\"text-align: center;\">[latex]\\text{2Al}\\left(s\\right)+\\text{2NaOH}\\left(aq\\right)+{\\text{6H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{2Na}\\left[\\text{Al}{\\left(\\text{OH}\\right)}_{4}\\right]\\left(aq\\right)+{\\text{3H}}_{2}\\left(g\\right)[\/latex]<\/p>\n<p>With both acids and bases, the reaction with aluminum generates hydrogen gas.<\/p>\n<p>The group 13 elements have a valence shell electron configuration of <em>ns<\/em><sup>2<\/sup><em>np<\/em><sup>1<\/sup>. Aluminum normally uses all of its valence electrons when it reacts, giving compounds in which it has an oxidation state of 3+. Although many of these compounds are covalent, others, such as AlF<sub>3<\/sub> and Al<sub>2<\/sub>(SO<sub>4<\/sub>)<sub>3<\/sub>, are ionic. Aqueous solutions of aluminum salts contain the cation [latex]{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{6}\\right]}^{3+},[\/latex] abbreviated as Al<sup>3+<\/sup>(<em>aq<\/em>). Gallium, indium, and thallium also form ionic compounds containing M<sup>3+<\/sup> ions. These three elements exhibit not only the expected oxidation state of 3+ from the three valence electrons but also an oxidation state (in this case, 1+) that is two below the expected value. This phenomenon, the inert pair effect, refers to the formation of a stable ion with an oxidation state two lower than expected for the group. The pair of electrons is the valence <em>s<\/em> orbital for those elements. In general, the inert pair effect is important for the lower <em>p<\/em>-block elements. In an aqueous solution, the Tl<sup>+<\/sup>(<em>aq<\/em>) ion is more stable than is Tl<sup>3+<\/sup>(<em>aq<\/em>). In general, these metals will react with air and water to form 3+ ions; however, thallium reacts to give thallium(I) derivatives. The metals of group 13 all react directly with nonmetals such as sulfur, phosphorus, and the halogens, forming binary compounds.<\/p>\n<p>The metals of group 13 (Al, Ga, In, and Tl) are all reactive. However, passivation occurs as a tough, hard, thin film of the metal oxide forms upon exposure to air. Disruption of this film may counter the passivation, allowing the metal to react. One way to disrupt the film is to expose the passivated metal to mercury. Some of the metal dissolves in the mercury to form an amalgam, which sheds the protective oxide layer to expose the metal to further reaction. The formation of an amalgam allows the metal to react with air and water.<\/p>\n<div class=\"textbox\">\n<p>Although easily oxidized, the passivation of aluminum makes it very useful as a strong, lightweight building material. Because of the formation of an amalgam, mercury is corrosive to structural materials made of aluminum. This video demonstrates how the integrity of an aluminum beam can be destroyed by the addition of a small amount of elemental mercury.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"Mercury attacks Aluminum\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/Z7Ilxsu-JlY?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/div>\n<p>The most important uses of aluminum are in the construction and transportation industries, and in the manufacture of aluminum cans and aluminum foil. These uses depend on the lightness, toughness, and strength of the metal, as well as its resistance to corrosion. Because aluminum is an excellent conductor of heat and resists corrosion, it is useful in the manufacture of cooking utensils.<\/p>\n<p>Aluminum is a very good reducing agent and may replace other reducing agents in the isolation of certain metals from their oxides. Although more expensive than reduction by carbon, aluminum is important in the isolation of Mo, W, and Cr from their oxides.<\/p>\n<h2 data-type=\"title\">Group 14<\/h2>\n<p>The metallic members of group 14 are tin, lead, and flerovium. Carbon is a typical nonmetal. The remaining elements of the group, silicon and germanium, are examples of semimetals or metalloids. Tin and lead form the stable divalent cations, Sn<sup>2+<\/sup> and Pb<sup>2+<\/sup>, with oxidation states two below the group oxidation state of 4+. The stability of this oxidation state is a consequence of the inert pair effect. Tin and lead also form covalent compounds with a formal 4+-oxidation state. For example, SnCl<sub>4<\/sub> and PbCl<sub>4<\/sub> are low-boiling covalent liquids.<\/p>\n<div id=\"attachment_2324\" style=\"width: 985px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2324\" class=\"size-full wp-image-2324\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23212459\/CNX_Chem_18_01_TinChlorid1.jpg\" alt=\"Two photos are shown and labeled \u201ca\u201d and \u201cb.\u201d Photo a shows a watch glass holding a fine, white powder. Photo b shows a sealed glass vial holding a clear, colorless liquid.\" width=\"975\" height=\"432\" \/><\/p>\n<p id=\"caption-attachment-2324\" class=\"wp-caption-text\">Figure\u00a08. (a) Tin(II) chloride is an ionic solid; (b) tin(IV) chloride is a covalent liquid.<\/p>\n<\/div>\n<p>Tin reacts readily with nonmetals and acids to form tin(II) compounds (indicating that it is more easily oxidized than hydrogen) and with nonmetals to form either tin(II) or tin(IV) compounds (shown in Figure\u00a08), depending on the stoichiometry and reaction conditions. Lead is less reactive. It is only slightly easier to oxidize than hydrogen, and oxidation normally requires a hot concentrated acid.<\/p>\n<p>Many of these elements exist as allotropes. <b>Allotropes<\/b> are two or more forms of the same element in the same physical state with different chemical and physical properties. There are two common allotropes of tin. These allotropes are grey (brittle) tin and white tin. As with other allotropes, the difference between these forms of tin is in the arrangement of the atoms. White tin is stable above 13.2 \u00b0C and is malleable like other metals. At low temperatures, gray tin is the more stable form. Gray tin is brittle and tends to break down to a powder. Consequently, articles made of tin will disintegrate in cold weather, particularly if the cold spell is lengthy. The change progresses slowly from the spot of origin, and the gray tin that is first formed catalyzes further change. In a way, this effect is similar to the spread of an infection in a plant or animal body, leading people to call this process tin disease or tin pest.<\/p>\n<p>The principal use of tin is in the coating of steel to form tin plate-sheet iron, which constitutes the tin in tin cans. Important tin alloys are bronze (Cu and Sn) and solder (Sn and Pb). Lead is important in the lead storage batteries in automobiles.<\/p>\n<h2 data-type=\"title\">Group 15<\/h2>\n<p><b>Bismuth<\/b>, the heaviest member of group 15, is a less reactive metal than the other representative metals. It readily gives up three of its five valence electrons to active nonmetals to form the tri-positive ion, Bi<sup>3+<\/sup>. It forms compounds with the group oxidation state of 5+ only when treated with strong oxidizing agents. The stability of the 3+-oxidation state is another example of the inert pair effect.<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>Key Concepts and Summary<\/h3>\n<p>This section focuses on the periodicity of the representative elements. These are the elements where the electrons are entering the <em>s<\/em> and <em>p<\/em> orbitals. The representative elements occur in groups 1, 2, and 12\u201318. These elements are representative metals, metalloids, and nonmetals. The alkali metals (group 1) are very reactive, readily form ions with a charge of 1+ to form ionic compounds that are usually soluble in water, and react vigorously with water to form hydrogen gas and a basic solution of the metal hydroxide. The outermost electrons of the alkaline earth metals (group 2) are more difficult to remove than the outer electron of the alkali metals, leading to the group 2 metals being less reactive than those in group 1. These elements easily form compounds in which the metals exhibit an oxidation state of 2+. Zinc, cadmium, and mercury (group 12) commonly exhibit the group oxidation state of 2+ (although mercury also exhibits an oxidation state of 1+ in compounds that contain [latex]{\\text{Hg}}_{2}{}^{2+}[\/latex] ). Aluminum, gallium, indium, and thallium (group 13) are easier to oxidize than is hydrogen. Aluminum, gallium, and indium occur with an oxidation state 3+ (however, thallium also commonly occurs as the Tl<sup>+<\/sup> ion). Tin and lead form stable divalent cations and covalent compounds in which the metals exhibit the 4+-oxidation state.<\/p>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Exercises<\/h3>\n<ol>\n<li id=\"fs-idp133644368\">How do alkali metals differ from alkaline earth metals in atomic structure and general properties?<\/li>\n<li>Why does the reactivity of the alkali metals decrease from cesium to lithium?<\/li>\n<li>Predict the formulas for the nine compounds that may form when each species in column 1 of the table below\u00a0reacts with each species in column 2.<br \/>\n<table>\n<thead>\n<tr valign=\"top\">\n<th>1<\/th>\n<th>2<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr valign=\"top\">\n<td>Na<\/td>\n<td>I<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td>Sr<\/td>\n<td>Se<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td>Al<\/td>\n<td>O<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/li>\n<li>Predict the best choice in each of the following. You may wish to review the chapter on electronic structure for relevant examples.\n<ol style=\"list-style-type: lower-alpha;\">\n<li>the most metallic of the elements Al, Be, and Ba<\/li>\n<li>the most covalent of the compounds NaCl, CaCl<sub>2<\/sub>, and BeCl<sub>2<\/sub><\/li>\n<li>the lowest first ionization energy among the elements Rb, K, and Li<\/li>\n<li>the smallest among Al, Al<sup>+<\/sup>, and Al<sup>3+<\/sup><\/li>\n<li>the largest among Cs<sup>+<\/sup>, Ba<sup>2+<\/sup>, and Xe<\/li>\n<\/ol>\n<\/li>\n<li>Sodium chloride and strontium chloride are both white solids. How could you distinguish one from the other?<\/li>\n<li>The reaction of quicklime, CaO, with water produces slaked lime, Ca(OH)<sub>2<\/sub>, which is widely used in the construction industry to make mortar and plaster. The reaction of quicklime and water is highly exothermic:[latex]\\text{CaO}\\left(s\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{Ca}{\\left(\\text{OH}\\right)}_{2}\\left(s\\right)[\/latex][latex]\\Delta H=-\\text{350 kJ}{\\text{mol}}^{-\\text{1}}[\/latex]\n<ol style=\"list-style-type: lower-alpha;\">\n<li>What is the enthalpy of reaction per gram of quicklime that reacts?<\/li>\n<li>How much heat, in kilojoules, is associated with the production of 1 ton of slaked lime?<\/li>\n<\/ol>\n<\/li>\n<li>Write a balanced equation for the reaction of elemental strontium with each of the following:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>oxygen<\/li>\n<li>hydrogen bromide<\/li>\n<li>hydrogen<\/li>\n<li>phosphorus<\/li>\n<li>water<\/li>\n<\/ol>\n<\/li>\n<li>How many moles of ionic species are present in 1.0 L of a solution marked 1.0 <em>M<\/em> mercury(I) nitrate?<\/li>\n<li>What is the mass of fish, in kilograms, that one would have to consume to obtain a fatal dose of mercury, if the fish contains 30 parts per million of mercury by weight? (Assume that all the mercury from the fish ends up as mercury(II) chloride in the body and that a fatal dose is 0.20 g of HgCl<sub>2<\/sub>.) How many pounds of fish is this?<\/li>\n<li>The elements sodium, aluminum, and chlorine are in the same period.\n<ol style=\"list-style-type: lower-alpha;\">\n<li>Which has the greatest electronegativity?<\/li>\n<li>Which of the atoms is smallest?<\/li>\n<li>Write the Lewis structure for the simplest covalent compound that can form between aluminum and chlorine.<\/li>\n<li>Will the oxide of each element be acidic, basic, or amphoteric?<\/li>\n<\/ol>\n<\/li>\n<li>Does metallic tin react with HCl?<\/li>\n<li>What is tin pest, also known as tin disease?<\/li>\n<li>Compare the nature of the bonds in PbCl<sub>2<\/sub> to that of the bonds in PbCl<sub>4<\/sub>.<\/li>\n<li>Is the reaction of rubidium with water more or less vigorous than that of sodium? How does the rate of reaction of magnesium compare?<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q331931\">Show Selected Answers<\/span><\/p>\n<div id=\"q331931\" class=\"hidden-answer\" style=\"display: none\">\n<p>1.\u00a0The alkali metals all have a single <em>s<\/em> electron in their outermost shell. In contrast, the alkaline earth metals have a completed <em>s<\/em> subshell in their outermost shell. In general, the alkali metals react faster and are more reactive than the corresponding alkaline earth metals in the same period.<\/p>\n<p>3. The formulas are as follows:<\/p>\n<p>[latex]\\begin{array}{l}\\text{Na}+{\\text{I}}_{2}\\rightarrow\\text{2NaI}\\\\ \\text{2Na}+\\text{Se}\\rightarrow{\\text{Na}}_{2}\\text{Se}\\\\ \\text{2Na}+{\\text{O}}_{2}\\rightarrow{\\text{Na}}_{2}{\\text{O}}_{2}\\end{array}[\/latex]<\/p>\n<p>[latex]\\begin{array}{l}\\text{Sr}+{\\text{I}}_{2}\\rightarrow{\\text{SrI}}_{2}\\\\ \\text{Sr}+\\text{Se}\\rightarrow\\text{SeSe}\\\\ \\text{2Sr}+{\\text{O}}_{2}\\rightarrow\\text{2SrO}\\end{array}[\/latex]<\/p>\n<p>[latex]\\begin{array}{l}\\text{2Al}+{\\text{3I}}_{2}\\rightarrow{\\text{2AlI}}_{3}\\\\ \\text{2Al}+\\text{3Se}\\rightarrow{\\text{Al}}_{2}{\\text{Se}}_{3}\\\\ \\text{4Al}+{\\text{3O}}_{2}\\rightarrow{\\text{2Al}}_{2}{\\text{O}}_{3}\\end{array}[\/latex]<\/p>\n<p>5.\u00a0The possible ways of distinguishing between the two include infrared spectroscopy by comparison of known compounds, a flame test that gives the characteristic yellow color for sodium (strontium has a red flame), or comparison of their solubilities in water. At 20 \u00b0C, NaCl dissolves to the extent of [latex]\\frac{\\text{35.7 g}}{\\text{100 mL}}[\/latex] compared with [latex]\\frac{\\text{53.8 g}}{\\text{100 mL}}[\/latex] for SrCl<sub>2<\/sub>. Heating to 100 \\textdegree C provides an easy test, since the solubility of NaCl is [latex]\\frac{\\text{39.12 g}}{\\text{100 mL}},[\/latex] but that of SrCl<sub>2<\/sub> is [latex]\\frac{\\text{100.8 g}}{\\text{100 mL}}.[\/latex] Density determination on a solid is sometimes difficult, but there is enough difference (2.165 g\/mL NaCl and 3.052 g\/mL SrCl<sub>2<\/sub>) that this method would be viable and perhaps the easiest and least expensive test to perform.<\/p>\n<p>7. The balanced equations are as follows:<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[latex]\\text{2Sr}\\left(s\\right)+{\\text{O}}_{2}\\left(g\\right)\\rightarrow\\text{2SrO}\\left(s\\right)[\/latex]<\/li>\n<li>[latex]\\text{Sr}\\left(s\\right)+\\text{2HBr}\\left(g\\right)\\rightarrow{\\text{SrBr}}_{2}\\left(s\\right)+{\\text{H}}_{2}\\left(g\\right)[\/latex]<\/li>\n<li>[latex]\\text{Sr}\\left(s\\right)+{\\text{H}}_{2}\\left(g\\right)\\rightarrow{\\text{SrH}}_{2}\\left(s\\right)[\/latex]<\/li>\n<li>[latex]\\text{6Sr}\\left(s\\right)+{\\text{P}}_{4}\\left(s\\right)\\rightarrow{\\text{2Sr}}_{3}{\\text{P}}_{2}\\left(s\\right)[\/latex]<\/li>\n<li>[latex]\\text{Sr}\\left(s\\right)+{\\text{2H}}_{2}\\text{O}\\left(l\\right)\\rightarrow\\text{Sr}{\\left(\\text{OH}\\right)}_{2}\\left(aq\\right)+{\\text{H}}_{2}\\left(g\\right)[\/latex]<\/li>\n<\/ol>\n<p>9.\u00a0The mass of Hg in 0.20 g HgCl<sub>2<\/sub> is [latex]0.20\\cancel{{\\text{g HgCl}}_{2}}\\times \\frac{\\text{200.59 g Hg}}{271.50\\cancel{{\\text{g HgCl}}_{2}}}=\\text{0.15 g Hg}.[\/latex]<\/p>\n<p>Then [latex]\\frac{30}{1\\times {10}^{6}}\\times \\text{mass of fish}=\\text{0.15 g Hg}.[\/latex] Mass of fish = 5.0 \u00d7 10<sup>3<\/sup> g. To convert to units of pounds, [latex]5.0\\times {10}^{3}\\cancel{\\text{g}}\\times \\frac{\\text{1 lb}}{453.6\\cancel{\\text{g}}}=\\text{11 lb}[\/latex]<\/p>\n<p>11.\u00a0Yes, tin reacts with hydrochloric acid to produce hydrogen gas. This ability can be determined from the standard reduction potentials in <a class=\"target-chapter\" href=\".\/chapter\/standard-electrode-half-cell-potentials\/\" target=\"_blank\">Standard Electrode (Half-Cell) Potentials<\/a>.<\/p>\n<p>13.\u00a0In PbCl<sub>2<\/sub>, the bonding is ionic, as indicated by its melting point of 501 \u00b0C. In PbCl<sub>4<\/sub>, the bonding is covalent, as evidenced by it being an unstable liquid at room temperature.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<h2>Glossary<\/h2>\n<p><b>alkaline earth metal: <\/b>any of the metals (beryllium, magnesium, calcium, strontium, barium, and radium) occupying group 2 of the periodic table; they are reactive, divalent metals that form basic oxides<\/p>\n<p><b>allotropes: <\/b>two or more forms of the same element, in the same physical state, with different chemical structures<\/p>\n<p><b>bismuth: <\/b>heaviest member of group 15; a less reactive metal than other representative metals<\/p>\n<p><b>metal: <\/b>atoms of the metallic elements of groups 1, 2, 12, 13, 14, 15, and 16, which form ionic compounds by losing electrons from their outer <em>s<\/em> or <em>p<\/em> orbitals<\/p>\n<p><b>metalloid: <\/b>element that has properties that are between those of metals and nonmetals; these elements are typically semiconductors<\/p>\n<p><b>passivation: <\/b>metals with a protective nonreactive film of oxide or other compound that creates a barrier for chemical reactions; physical or chemical removal of the passivating film allows the metals to demonstrate their expected chemical reactivity<\/p>\n<p><b>representative element: <\/b>element where the <em>s<\/em> and <em>p<\/em> orbitals are filling<\/p>\n<p><b>representative metal: <\/b>metal among the representative elements<\/p>\n<p><b>salt: <\/b>ionic compound consisting of cations and anions<\/p>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-2326\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Chemistry. <strong>Provided by<\/strong>: OpenStax College. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/openstaxcollege.org\">http:\/\/openstaxcollege.org<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at https:\/\/openstaxcollege.org\/textbooks\/chemistry\/get<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":17,"menu_order":2,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Chemistry\",\"author\":\"\",\"organization\":\"OpenStax College\",\"url\":\"http:\/\/openstaxcollege.org\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at https:\/\/openstaxcollege.org\/textbooks\/chemistry\/get\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-2326","chapter","type-chapter","status-publish","hentry"],"part":2963,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/2326","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":11,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/2326\/revisions"}],"predecessor-version":[{"id":6059,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/2326\/revisions\/6059"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/parts\/2963"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/2326\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/media?parent=2326"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapter-type?post=2326"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/contributor?post=2326"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/license?post=2326"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}