{"id":1742,"date":"2015-04-22T19:02:50","date_gmt":"2015-04-22T19:02:50","guid":{"rendered":"https:\/\/courses.candelalearning.com\/oschemtemp\/?post_type=chapter&#038;p=1742"},"modified":"2016-10-27T15:53:34","modified_gmt":"2016-10-27T15:53:34","slug":"ionic-bonding","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/chapter\/ionic-bonding\/","title":{"raw":"Ionic Bonding","rendered":"Ionic Bonding"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\nBy the end of this section, you will be able to:\r\n<ul>\r\n \t<li>Explain the formation of cations, anions, and ionic compounds<\/li>\r\n \t<li>Predict the charge of common metallic and nonmetallic elements, and write their electron configurations<\/li>\r\n<\/ul>\r\n<\/div>\r\nAs you have learned, ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell.\r\n\r\nCompounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by <strong>ionic bonds<\/strong>: electrostatic forces of attraction between oppositely charged cations and anions. The properties of ionic compounds shed some light on the nature of ionic bonds. Ionic solids exhibit a crystalline structure and tend to be rigid and brittle; they also tend to have high melting and boiling points, which suggests that ionic bonds are very strong. Ionic solids are also poor conductors of electricity for the same reason\u2014the strength of ionic bonds prevents ions from moving freely in the solid state. Most ionic solids, however, dissolve readily in water. Once dissolved or melted, ionic compounds are excellent conductors of electricity and heat because the ions can move about freely.\r\n\r\nNeutral atoms and their associated ions have very different physical and chemical properties. Sodium <em>atoms<\/em> form sodium metal, a soft, silvery-white metal that burns vigorously in air and reacts explosively with water. Chlorine <em>atoms<\/em> form chlorine gas, Cl<sub>2<\/sub>, a yellow-green gas that is extremely corrosive to most metals and very poisonous to animals and plants. The vigorous reaction between the elements sodium and chlorine forms the white, crystalline compound sodium chloride, common table salt, which contains sodium <em>cations<\/em> and chloride <em>anions<\/em> (Figure 1). The compound composed of these ions exhibits properties entirely different from the properties of the elements sodium and chlorine. Chlorine is poisonous, but sodium chloride is essential to life; sodium atoms react vigorously with water, but sodium chloride simply dissolves in water.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"880\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211342\/CNX_Chem_07_01_NaClPhotos1.jpg\" alt=\"Three pictures are shown and labeled \u201ca,\u201d \u201cb,\u201d and \u201cc,\u201d from left to right. Image a shows a glass jar with a lid that is full of a clear, colorless liquid in which a silver solid is suspended. Image b depicts a glass bottle with a blue lid that is full of a yellow-green gas. Image c shows a black dish that is full of a white, crystalline solid.\" width=\"880\" height=\"295\" data-media-type=\"image\/jpeg\" \/> Figure 1. (a) Sodium is a soft metal that must be stored in mineral oil to prevent reaction with air or water. (b) Chlorine is a pale yellow-green gas. (c) When combined, they form white crystals of sodium chloride (table salt). (credit a: modification of work by \u201cJurii\u201d\/Wikimedia Commons)[\/caption]\r\n<h2 data-type=\"title\">The Formation of Ionic Compounds<\/h2>\r\nBinary ionic compounds are composed of just two elements: a metal (which forms the cations) and a nonmetal (which forms the anions). For example, NaCl is a binary ionic compound. We can think about the formation of such compounds in terms of the periodic properties of the elements. Many metallic elements have relatively low ionization potentials and lose electrons easily. These elements lie to the left in a period or near the bottom of a group on the periodic table. Nonmetal atoms have relatively high electron affinities and thus readily gain electrons lost by metal atoms, thereby filling their valence shells. Nonmetallic elements are found in the upper-right corner of the periodic table.\r\n\r\nAs all substances must be electrically neutral, the total number of positive charges on the cations of an ionic compound must equal the total number of negative charges on its anions. The formula of an ionic compound represents the simplest ratio of the numbers of ions necessary to give identical numbers of positive and negative charges. For example, the formula for aluminum oxide, Al<sub>2<\/sub>O<sub>3<\/sub>, indicates that this ionic compound contains two aluminum cations, Al<sup>3+<\/sup>, for every three oxide anions, O<sup>2-<\/sup> [thus, (2 \u00d7 +3) + (3 \u00d7 \u20132) = 0].\r\n\r\nIt is important to note, however, that the formula for an ionic compound does <em>not<\/em> represent the physical arrangement of its ions. It is incorrect to refer to a sodium chloride (NaCl) \u201cmolecule\u201d because there is not a single ionic bond, per se, between any specific pair of sodium and chloride ions. The attractive forces between ions are isotropic\u2014the same in all directions\u2014meaning that any particular ion is equally attracted to all of the nearby ions of opposite charge. This results in the ions arranging themselves into a tightly bound, three-dimensional lattice structure. Sodium chloride, for example, consists of a regular arrangement of equal numbers of Na<sup>+<\/sup> cations and Cl<sup>\u2013<\/sup> anions (Figure 2).\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"519\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211343\/CNX_Chem_07_01_NaClStruc1.jpg\" alt=\"Two diagrams are shown and labeled \u201ca\u201d and \u201cb.\u201d Diagram a shows a cube made up of twenty-seven alternating purple and green spheres. The purple spheres are smaller than the green spheres. Diagram b shows the same spheres, but this time, they are spread out and connected in three dimensions by white rods. The purple spheres are labeled \u201cN superscript postive sign\u201d while the green are labeled \u201cC l superscript negative sign.\u201d\" width=\"519\" height=\"327\" data-media-type=\"image\/jpeg\" \/> Figure 2. The atoms in sodium chloride (common table salt) are arranged to (a) maximize opposite charges interacting. The smaller spheres represent sodium ions, the larger ones represent chloride ions. In the expanded view (b), the geometry can be seen more clearly. Note that each ion is \u201cbonded\u201d to all of the surrounding ions\u2014six in this case.[\/caption]\r\n\r\nThe strong electrostatic attraction between Na<sup>+<\/sup> and Cl<sup>\u2013<\/sup> ions holds them tightly together in solid NaCl. It requires 769 kJ of energy to dissociate one mole of solid NaCl into separate gaseous Na<sup>+<\/sup> and Cl<sup>\u2013<\/sup> ions:\r\n[latex]\\text{NaCl}\\left(s\\right)\\rightarrow{\\text{Na}}^{\\text{+}}\\left(g\\right)+{\\text{Cl}}^{-}\\left(g\\right)\\Delta H=769\\text{kJ}[\/latex]\r\n<h2 data-type=\"title\">Electronic Structures of Cations<\/h2>\r\nWhen forming a cation, an atom of a main group element tends to lose all of its valence electrons, thus assuming the electronic structure of the noble gas that precedes it in the periodic table. For groups 1 (the alkali metals) and 2 (the alkaline earth metals), the group numbers are equal to the numbers of valence shell electrons and, consequently, to the charges of the cations formed from atoms of these elements when all valence shell electrons are removed. For example, calcium is a group 2 element whose neutral atoms have 20 electrons and a ground state electron configuration of 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>4<em>s<\/em><sup>2<\/sup>. When a Ca atom loses both of its valence electrons, the result is a cation with 18 electrons, a 2+ charge, and an electron configuration of 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>. The Ca<sup>2+<\/sup> ion is therefore isoelectronic with the noble gas Ar.\r\n\r\nFor groups 12\u201317, the group numbers exceed the number of valence electrons by 10 (accounting for the possibility of full <em>d<\/em> subshells in atoms of elements in the fourth and greater periods). Thus, the charge of a cation formed by the loss of all valence electrons is equal to the group number minus 10. For example, aluminum (in group 13) forms 3+ ions (Al<sup>3+<\/sup>).\r\n\r\nExceptions to the expected behavior involve elements toward the bottom of the groups. In addition to the expected ions Tl<sup>3+<\/sup>, Sn<sup>4+<\/sup>, Pb<sup>4+<\/sup>, and Bi<sup>5+<\/sup>, a partial loss of these atoms\u2019 valence shell electrons can also lead to the formation of Tl<sup>+<\/sup>, Sn<sup>2+<\/sup>, Pb<sup>2+<\/sup>, and Bi<sup>3+<\/sup> ions. The formation of these 1+, 2+, and 3+ cations is ascribed to the <strong>inert pair effect<\/strong>, which reflects the relatively low energy of the valence <em>s<\/em>-electron pair for atoms of the heavy elements of groups 13, 14, and 15. Mercury (group 12) also exhibits an unexpected behavior: it forms a diatomic ion, [latex]{\\text{Hg}}_{2}{}^{\\text{2+}}[\/latex] (an ion formed from two mercury atoms, with an Hg-Hg bond), in addition to the expected monatomic ion Hg<sup>2+<\/sup> (formed from only one mercury atom).\r\n\r\nTransition and inner transition metal elements behave differently than main group elements. Most transition metal cations have 2+ or 3+ charges that result from the loss of their outermost <em>s<\/em> electron(s) first, sometimes followed by the loss of one or two <em>d<\/em> electrons from the next-to-outermost shell. For example, iron (1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>6<\/sup>4<em>s<\/em><sup>2<\/sup>) forms the ion Fe<sup>2+<\/sup> (1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>6<\/sup>4<em>s<\/em><sup>2<\/sup>) by the loss of the 4<em>s<\/em> electron and the ion Fe<sup>3+<\/sup> (1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>5<\/sup>) by the loss of the 4<em>s<\/em> electron and one of the 3<em>d<\/em> electrons. Although the <em>d<\/em> orbitals of the transition elements are\u2014according to the Aufbau principle\u2014the last to fill when building up electron configurations, the outermost <em>s<\/em> electrons are the first to be lost when these atoms ionize. When the inner transition metals form ions, they usually have a 3+ charge, resulting from the loss of their outermost <em>s<\/em> electrons and a <em>d<\/em> or <em>f<\/em> electron.\r\n<div class=\"textbox examples\">\r\n<h3>Example 1:\u00a0Determining the Electronic Structures of Cations<\/h3>\r\nThere are at least 14 elements categorized as \u201cessential trace elements\u201d for the human body. They are called \u201cessential\u201d because they are required for healthy bodily functions, \u201ctrace\u201d because they are required only in small amounts, and \u201celements\u201d in spite of the fact that they are really ions. Two of these essential trace elements, chromium and zinc, are required as Cr<sup>3+<\/sup> and Zn<sup>2+<\/sup>. Write the electron configurations of these cations.\r\n[reveal-answer q=\"807563\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"807563\"]\r\n\r\nFirst, write the electron configuration for the neutral atoms:\r\n\r\nZn: [Ar]3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>\r\n\r\nCr: [Ar]3<em>d<\/em><sup>3<\/sup>4<em>s<\/em><sup>1<\/sup>\r\n\r\nNext, remove electrons from the highest energy orbital. For the transition metals, electrons are removed from the <em>s<\/em> orbital first and then from the <em>d<\/em> orbital. For the <em>p<\/em>-block elements, electrons are removed from the <em>p<\/em> orbitals and then from the <em>s<\/em> orbital. Zinc is a member of group 12, so it should have a charge of 2+, and thus loses only the two electrons in its <em>s<\/em> orbital. Chromium is a transition element and should lose its <em>s<\/em> electrons and then its <em>d<\/em> electrons when forming a cation. Thus, we find the following electron configurations of the ions:\r\n\r\nZn<sup>2+<\/sup>: [Ar]3<em>d<\/em><sup>10<\/sup>\r\n\r\nCr<sup>3+<\/sup>: [Ar]3<em>d<\/em><sup>3<\/sup>\r\n\r\n[\/hidden-answer]\r\n<h4><strong>Check Your Learning<\/strong><\/h4>\r\nPotassium and magnesium are required in our diet. Write the electron configurations of the ions expected from these elements.\r\n\r\n[reveal-answer q=\"761065\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"761065\"]K<sup>+<\/sup>: [Ar], Mg<sup>2+<\/sup>: [Ne][\/hidden-answer]\r\n\r\n<\/div>\r\n<h2>Electronic Structures of Anions<\/h2>\r\nMost monatomic anions form when a neutral nonmetal atom gains enough electrons to completely fill its outer <em>s<\/em> and <em>p<\/em> orbitals, thereby reaching the electron configuration of the next noble gas. Thus, it is simple to determine the charge on such a negative ion: The charge is equal to the number of electrons that must be gained to fill the <em>s<\/em> and <em>p<\/em> orbitals of the parent atom. Oxygen, for example, has the electron configuration 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>4<\/sup>, whereas the oxygen anion has the electron configuration of the noble gas neon (Ne), 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>. The two additional electrons required to fill the valence orbitals give the oxide ion the charge of 2\u2013 (O<sup>2\u2013<\/sup>).\r\n<div class=\"textbox examples\">\r\n<h3>Example 2:\u00a0Determining the Electronic Structure of Anions<\/h3>\r\nSelenium and iodine are two essential trace elements that form anions. Write the electron configurations of the anions.\r\n[reveal-answer q=\"348167\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"348167\"]\r\n\r\nSe<sup>2\u2013<\/sup>: [Ar]3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup>\r\n\r\nI<sup>\u2013<\/sup>: [Kr]4<em>d<\/em><sup>10<\/sup>5<em>s<\/em><sup>2<\/sup>5<em>p<\/em><sup>6<\/sup>\r\n\r\n[\/hidden-answer]\r\n<h4><strong>Check Your Learning<\/strong><\/h4>\r\nWrite the electron configurations of a phosphorus atom and its negative ion. Give the charge on the anion.\r\n\r\n[reveal-answer q=\"245923\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"245923\"]P: [Ne]3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>3<\/sup>; P<sup>3\u2013<\/sup>: [Ne]<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Key Concepts and Summary<\/h3>\r\nAtoms gain or lose electrons to form ions with particularly stable electron configurations. The charges of cations formed by the representative metals may be determined readily because, with few exceptions, the electronic structures of these ions have either a noble gas configuration or a completely filled electron shell. The charges of anions formed by the nonmetals may also be readily determined because these ions form when nonmetal atoms gain enough electrons to fill their valence shells.\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Exercises<\/h3>\r\n<ol>\r\n \t<li>Does a cation gain protons to form a positive charge or does it lose electrons?<\/li>\r\n \t<li>Iron(III) sulfate [Fe<sub>2<\/sub>(SO<sub>4<\/sub>)<sub>3<\/sub>] is composed of Fe<sup>3+<\/sup> and [latex]{\\text{SO}}_{4}{}^{\\text{2-}}[\/latex] ions. Explain why a sample of iron(III) sulfate is uncharged.<\/li>\r\n \t<li>Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: P, I, Mg, Cl, In, Cs, O, Pb, Co?<\/li>\r\n \t<li>Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: Br, Ca, Na, N, F, Al, Sn, S, Cd?<\/li>\r\n \t<li>Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>P<\/li>\r\n \t<li>Mg<\/li>\r\n \t<li>Al<\/li>\r\n \t<li>O<\/li>\r\n \t<li>Cl<\/li>\r\n \t<li>Cs<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>I<\/li>\r\n \t<li>Sr<\/li>\r\n \t<li>K<\/li>\r\n \t<li>N<\/li>\r\n \t<li>S<\/li>\r\n \t<li>In<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Write the electron configuration for each of the following ions:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>As<sup>3\u2013 <\/sup><\/li>\r\n \t<li>I<sup>\u2013 <\/sup><\/li>\r\n \t<li>Be<sup>2+ <\/sup><\/li>\r\n \t<li>Cd<sup>2+ <\/sup><\/li>\r\n \t<li>O<sup>2\u2013 <\/sup><\/li>\r\n \t<li>Ga<sup>3+\u00a0<\/sup><\/li>\r\n \t<li>Li<sup>+\u00a0<\/sup><\/li>\r\n \t<li>N<sup>3\u2013\u00a0<\/sup><\/li>\r\n \t<li>Sn<sup>2+\u00a0<\/sup><\/li>\r\n \t<li>Co<sup>2+\u00a0<\/sup><\/li>\r\n \t<li>Fe<sup>2+\u00a0<\/sup><\/li>\r\n \t<li>As<sup>3+<\/sup><\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Write the electron configuration for the monatomic ions formed from the following elements (which form the greatest concentration of monatomic ions in seawater):\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>Cl<\/li>\r\n \t<li>Na<\/li>\r\n \t<li>Mg<\/li>\r\n \t<li>Ca<\/li>\r\n \t<li>K<\/li>\r\n \t<li>Br<\/li>\r\n \t<li>Sr<\/li>\r\n \t<li>F<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Write out the full electron configuration for each of the following atoms and for the monatomic ion found in binary ionic compounds containing the element:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>Al<\/li>\r\n \t<li>Br<\/li>\r\n \t<li>Sr<\/li>\r\n \t<li>Li<\/li>\r\n \t<li>As<\/li>\r\n \t<li>S<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>From the labels of several commercial products, prepare a list of six ionic compounds in the products. For each compound, write the formula. (You may need to look up some formulas in a suitable reference.)<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"614212\"]Selected Answers[\/reveal-answer]\r\n[hidden-answer a=\"614212\"]\r\n\r\n1. The protons in the nucleus do not change during normal chemical reactions. Only the outer electrons move. Positive charges form when electrons are lost.\r\n\r\n3. P, I, Cl, and O would form anions because they are nonmetals. Mg, In, Cs, Pb, and Co would form cations because they are metals.\r\n\r\n5. The\u00a0predicted charges are as follows:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>P<sup>3\u2013<\/sup><\/li>\r\n \t<li>Mg<sup>2+<\/sup><\/li>\r\n \t<li>Al<sup>3+<\/sup><\/li>\r\n \t<li>O<sup>2\u2013<\/sup><\/li>\r\n \t<li>Cl<sup>\u2013<\/sup><\/li>\r\n \t<li>Cs<sup>+<\/sup><\/li>\r\n<\/ol>\r\n7. The correct electron configurations are\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[Ar] 3<em>d<\/em><sup>10<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>[Kr] 4<em>d<\/em><sup>10<\/sup>5<em>s<\/em><sup>2<\/sup>5<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>1<em>s<\/em><sup>2<\/sup><\/li>\r\n \t<li>[Kr] 4<em>d<\/em><sup>8<\/sup><\/li>\r\n \t<li>[He] 2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>[Ar] 3<em>d<\/em><sup>10<\/sup><\/li>\r\n \t<li>1<em>s<\/em><sup>2<\/sup><\/li>\r\n \t<li>[He] 2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>[Kr] <em>d<\/em><sup>10<\/sup>5<em>s<\/em><sup>2<\/sup><\/li>\r\n \t<li>[Ar] 3<em>d<\/em><sup>7<\/sup><\/li>\r\n \t<li>[Ar] 3<em>d<\/em><sup>6<\/sup><\/li>\r\n \t<li>[Ar] 3<em>d<\/em><sup>10<\/sup>4s<sup>2<\/sup><\/li>\r\n<\/ol>\r\n9.\u00a0The correct electron configurations are\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>1<\/sup>; Al<sup>3+ <\/sup>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>5<\/sup>; 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup>5<em>s<\/em><sup>2<\/sup>; Sr<sup>2+ <\/sup>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>1<\/sup>; Li<sup>+<\/sup> 1<em>s<\/em><sup>2<\/sup><\/li>\r\n \t<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>3<\/sup>; 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\r\n \t<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>4<\/sup>; 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup><\/li>\r\n<\/ol>\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<h2>Glossary<\/h2>\r\n<strong>inert pair effect:\u00a0<\/strong>tendency of heavy atoms to form ions in which their valence <em>s<\/em> electrons are not lost\r\n\r\n<strong>ionic bond:\u00a0<\/strong>strong electrostatic force of attraction between cations and anions in an ionic compound","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<p>By the end of this section, you will be able to:<\/p>\n<ul>\n<li>Explain the formation of cations, anions, and ionic compounds<\/li>\n<li>Predict the charge of common metallic and nonmetallic elements, and write their electron configurations<\/li>\n<\/ul>\n<\/div>\n<p>As you have learned, ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell.<\/p>\n<p>Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by <strong>ionic bonds<\/strong>: electrostatic forces of attraction between oppositely charged cations and anions. The properties of ionic compounds shed some light on the nature of ionic bonds. Ionic solids exhibit a crystalline structure and tend to be rigid and brittle; they also tend to have high melting and boiling points, which suggests that ionic bonds are very strong. Ionic solids are also poor conductors of electricity for the same reason\u2014the strength of ionic bonds prevents ions from moving freely in the solid state. Most ionic solids, however, dissolve readily in water. Once dissolved or melted, ionic compounds are excellent conductors of electricity and heat because the ions can move about freely.<\/p>\n<p>Neutral atoms and their associated ions have very different physical and chemical properties. Sodium <em>atoms<\/em> form sodium metal, a soft, silvery-white metal that burns vigorously in air and reacts explosively with water. Chlorine <em>atoms<\/em> form chlorine gas, Cl<sub>2<\/sub>, a yellow-green gas that is extremely corrosive to most metals and very poisonous to animals and plants. The vigorous reaction between the elements sodium and chlorine forms the white, crystalline compound sodium chloride, common table salt, which contains sodium <em>cations<\/em> and chloride <em>anions<\/em> (Figure 1). The compound composed of these ions exhibits properties entirely different from the properties of the elements sodium and chlorine. Chlorine is poisonous, but sodium chloride is essential to life; sodium atoms react vigorously with water, but sodium chloride simply dissolves in water.<\/p>\n<div style=\"width: 890px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211342\/CNX_Chem_07_01_NaClPhotos1.jpg\" alt=\"Three pictures are shown and labeled \u201ca,\u201d \u201cb,\u201d and \u201cc,\u201d from left to right. Image a shows a glass jar with a lid that is full of a clear, colorless liquid in which a silver solid is suspended. Image b depicts a glass bottle with a blue lid that is full of a yellow-green gas. Image c shows a black dish that is full of a white, crystalline solid.\" width=\"880\" height=\"295\" data-media-type=\"image\/jpeg\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 1. (a) Sodium is a soft metal that must be stored in mineral oil to prevent reaction with air or water. (b) Chlorine is a pale yellow-green gas. (c) When combined, they form white crystals of sodium chloride (table salt). (credit a: modification of work by \u201cJurii\u201d\/Wikimedia Commons)<\/p>\n<\/div>\n<h2 data-type=\"title\">The Formation of Ionic Compounds<\/h2>\n<p>Binary ionic compounds are composed of just two elements: a metal (which forms the cations) and a nonmetal (which forms the anions). For example, NaCl is a binary ionic compound. We can think about the formation of such compounds in terms of the periodic properties of the elements. Many metallic elements have relatively low ionization potentials and lose electrons easily. These elements lie to the left in a period or near the bottom of a group on the periodic table. Nonmetal atoms have relatively high electron affinities and thus readily gain electrons lost by metal atoms, thereby filling their valence shells. Nonmetallic elements are found in the upper-right corner of the periodic table.<\/p>\n<p>As all substances must be electrically neutral, the total number of positive charges on the cations of an ionic compound must equal the total number of negative charges on its anions. The formula of an ionic compound represents the simplest ratio of the numbers of ions necessary to give identical numbers of positive and negative charges. For example, the formula for aluminum oxide, Al<sub>2<\/sub>O<sub>3<\/sub>, indicates that this ionic compound contains two aluminum cations, Al<sup>3+<\/sup>, for every three oxide anions, O<sup>2-<\/sup> [thus, (2 \u00d7 +3) + (3 \u00d7 \u20132) = 0].<\/p>\n<p>It is important to note, however, that the formula for an ionic compound does <em>not<\/em> represent the physical arrangement of its ions. It is incorrect to refer to a sodium chloride (NaCl) \u201cmolecule\u201d because there is not a single ionic bond, per se, between any specific pair of sodium and chloride ions. The attractive forces between ions are isotropic\u2014the same in all directions\u2014meaning that any particular ion is equally attracted to all of the nearby ions of opposite charge. This results in the ions arranging themselves into a tightly bound, three-dimensional lattice structure. Sodium chloride, for example, consists of a regular arrangement of equal numbers of Na<sup>+<\/sup> cations and Cl<sup>\u2013<\/sup> anions (Figure 2).<\/p>\n<div style=\"width: 529px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211343\/CNX_Chem_07_01_NaClStruc1.jpg\" alt=\"Two diagrams are shown and labeled \u201ca\u201d and \u201cb.\u201d Diagram a shows a cube made up of twenty-seven alternating purple and green spheres. The purple spheres are smaller than the green spheres. Diagram b shows the same spheres, but this time, they are spread out and connected in three dimensions by white rods. The purple spheres are labeled \u201cN superscript postive sign\u201d while the green are labeled \u201cC l superscript negative sign.\u201d\" width=\"519\" height=\"327\" data-media-type=\"image\/jpeg\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 2. The atoms in sodium chloride (common table salt) are arranged to (a) maximize opposite charges interacting. The smaller spheres represent sodium ions, the larger ones represent chloride ions. In the expanded view (b), the geometry can be seen more clearly. Note that each ion is \u201cbonded\u201d to all of the surrounding ions\u2014six in this case.<\/p>\n<\/div>\n<p>The strong electrostatic attraction between Na<sup>+<\/sup> and Cl<sup>\u2013<\/sup> ions holds them tightly together in solid NaCl. It requires 769 kJ of energy to dissociate one mole of solid NaCl into separate gaseous Na<sup>+<\/sup> and Cl<sup>\u2013<\/sup> ions:<br \/>\n[latex]\\text{NaCl}\\left(s\\right)\\rightarrow{\\text{Na}}^{\\text{+}}\\left(g\\right)+{\\text{Cl}}^{-}\\left(g\\right)\\Delta H=769\\text{kJ}[\/latex]<\/p>\n<h2 data-type=\"title\">Electronic Structures of Cations<\/h2>\n<p>When forming a cation, an atom of a main group element tends to lose all of its valence electrons, thus assuming the electronic structure of the noble gas that precedes it in the periodic table. For groups 1 (the alkali metals) and 2 (the alkaline earth metals), the group numbers are equal to the numbers of valence shell electrons and, consequently, to the charges of the cations formed from atoms of these elements when all valence shell electrons are removed. For example, calcium is a group 2 element whose neutral atoms have 20 electrons and a ground state electron configuration of 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>4<em>s<\/em><sup>2<\/sup>. When a Ca atom loses both of its valence electrons, the result is a cation with 18 electrons, a 2+ charge, and an electron configuration of 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>. The Ca<sup>2+<\/sup> ion is therefore isoelectronic with the noble gas Ar.<\/p>\n<p>For groups 12\u201317, the group numbers exceed the number of valence electrons by 10 (accounting for the possibility of full <em>d<\/em> subshells in atoms of elements in the fourth and greater periods). Thus, the charge of a cation formed by the loss of all valence electrons is equal to the group number minus 10. For example, aluminum (in group 13) forms 3+ ions (Al<sup>3+<\/sup>).<\/p>\n<p>Exceptions to the expected behavior involve elements toward the bottom of the groups. In addition to the expected ions Tl<sup>3+<\/sup>, Sn<sup>4+<\/sup>, Pb<sup>4+<\/sup>, and Bi<sup>5+<\/sup>, a partial loss of these atoms\u2019 valence shell electrons can also lead to the formation of Tl<sup>+<\/sup>, Sn<sup>2+<\/sup>, Pb<sup>2+<\/sup>, and Bi<sup>3+<\/sup> ions. The formation of these 1+, 2+, and 3+ cations is ascribed to the <strong>inert pair effect<\/strong>, which reflects the relatively low energy of the valence <em>s<\/em>-electron pair for atoms of the heavy elements of groups 13, 14, and 15. Mercury (group 12) also exhibits an unexpected behavior: it forms a diatomic ion, [latex]{\\text{Hg}}_{2}{}^{\\text{2+}}[\/latex] (an ion formed from two mercury atoms, with an Hg-Hg bond), in addition to the expected monatomic ion Hg<sup>2+<\/sup> (formed from only one mercury atom).<\/p>\n<p>Transition and inner transition metal elements behave differently than main group elements. Most transition metal cations have 2+ or 3+ charges that result from the loss of their outermost <em>s<\/em> electron(s) first, sometimes followed by the loss of one or two <em>d<\/em> electrons from the next-to-outermost shell. For example, iron (1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>6<\/sup>4<em>s<\/em><sup>2<\/sup>) forms the ion Fe<sup>2+<\/sup> (1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>6<\/sup>4<em>s<\/em><sup>2<\/sup>) by the loss of the 4<em>s<\/em> electron and the ion Fe<sup>3+<\/sup> (1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>5<\/sup>) by the loss of the 4<em>s<\/em> electron and one of the 3<em>d<\/em> electrons. Although the <em>d<\/em> orbitals of the transition elements are\u2014according to the Aufbau principle\u2014the last to fill when building up electron configurations, the outermost <em>s<\/em> electrons are the first to be lost when these atoms ionize. When the inner transition metals form ions, they usually have a 3+ charge, resulting from the loss of their outermost <em>s<\/em> electrons and a <em>d<\/em> or <em>f<\/em> electron.<\/p>\n<div class=\"textbox examples\">\n<h3>Example 1:\u00a0Determining the Electronic Structures of Cations<\/h3>\n<p>There are at least 14 elements categorized as \u201cessential trace elements\u201d for the human body. They are called \u201cessential\u201d because they are required for healthy bodily functions, \u201ctrace\u201d because they are required only in small amounts, and \u201celements\u201d in spite of the fact that they are really ions. Two of these essential trace elements, chromium and zinc, are required as Cr<sup>3+<\/sup> and Zn<sup>2+<\/sup>. Write the electron configurations of these cations.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q807563\">Show Answer<\/span><\/p>\n<div id=\"q807563\" class=\"hidden-answer\" style=\"display: none\">\n<p>First, write the electron configuration for the neutral atoms:<\/p>\n<p>Zn: [Ar]3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup><\/p>\n<p>Cr: [Ar]3<em>d<\/em><sup>3<\/sup>4<em>s<\/em><sup>1<\/sup><\/p>\n<p>Next, remove electrons from the highest energy orbital. For the transition metals, electrons are removed from the <em>s<\/em> orbital first and then from the <em>d<\/em> orbital. For the <em>p<\/em>-block elements, electrons are removed from the <em>p<\/em> orbitals and then from the <em>s<\/em> orbital. Zinc is a member of group 12, so it should have a charge of 2+, and thus loses only the two electrons in its <em>s<\/em> orbital. Chromium is a transition element and should lose its <em>s<\/em> electrons and then its <em>d<\/em> electrons when forming a cation. Thus, we find the following electron configurations of the ions:<\/p>\n<p>Zn<sup>2+<\/sup>: [Ar]3<em>d<\/em><sup>10<\/sup><\/p>\n<p>Cr<sup>3+<\/sup>: [Ar]3<em>d<\/em><sup>3<\/sup><\/p>\n<\/div>\n<\/div>\n<h4><strong>Check Your Learning<\/strong><\/h4>\n<p>Potassium and magnesium are required in our diet. Write the electron configurations of the ions expected from these elements.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q761065\">Show Answer<\/span><\/p>\n<div id=\"q761065\" class=\"hidden-answer\" style=\"display: none\">K<sup>+<\/sup>: [Ar], Mg<sup>2+<\/sup>: [Ne]<\/div>\n<\/div>\n<\/div>\n<h2>Electronic Structures of Anions<\/h2>\n<p>Most monatomic anions form when a neutral nonmetal atom gains enough electrons to completely fill its outer <em>s<\/em> and <em>p<\/em> orbitals, thereby reaching the electron configuration of the next noble gas. Thus, it is simple to determine the charge on such a negative ion: The charge is equal to the number of electrons that must be gained to fill the <em>s<\/em> and <em>p<\/em> orbitals of the parent atom. Oxygen, for example, has the electron configuration 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>4<\/sup>, whereas the oxygen anion has the electron configuration of the noble gas neon (Ne), 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>. The two additional electrons required to fill the valence orbitals give the oxide ion the charge of 2\u2013 (O<sup>2\u2013<\/sup>).<\/p>\n<div class=\"textbox examples\">\n<h3>Example 2:\u00a0Determining the Electronic Structure of Anions<\/h3>\n<p>Selenium and iodine are two essential trace elements that form anions. Write the electron configurations of the anions.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q348167\">Show Answer<\/span><\/p>\n<div id=\"q348167\" class=\"hidden-answer\" style=\"display: none\">\n<p>Se<sup>2\u2013<\/sup>: [Ar]3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup><\/p>\n<p>I<sup>\u2013<\/sup>: [Kr]4<em>d<\/em><sup>10<\/sup>5<em>s<\/em><sup>2<\/sup>5<em>p<\/em><sup>6<\/sup><\/p>\n<\/div>\n<\/div>\n<h4><strong>Check Your Learning<\/strong><\/h4>\n<p>Write the electron configurations of a phosphorus atom and its negative ion. Give the charge on the anion.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q245923\">Show Answer<\/span><\/p>\n<div id=\"q245923\" class=\"hidden-answer\" style=\"display: none\">P: [Ne]3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>3<\/sup>; P<sup>3\u2013<\/sup>: [Ne]<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup><\/div>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Key Concepts and Summary<\/h3>\n<p>Atoms gain or lose electrons to form ions with particularly stable electron configurations. The charges of cations formed by the representative metals may be determined readily because, with few exceptions, the electronic structures of these ions have either a noble gas configuration or a completely filled electron shell. The charges of anions formed by the nonmetals may also be readily determined because these ions form when nonmetal atoms gain enough electrons to fill their valence shells.<\/p>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Exercises<\/h3>\n<ol>\n<li>Does a cation gain protons to form a positive charge or does it lose electrons?<\/li>\n<li>Iron(III) sulfate [Fe<sub>2<\/sub>(SO<sub>4<\/sub>)<sub>3<\/sub>] is composed of Fe<sup>3+<\/sup> and [latex]{\\text{SO}}_{4}{}^{\\text{2-}}[\/latex] ions. Explain why a sample of iron(III) sulfate is uncharged.<\/li>\n<li>Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: P, I, Mg, Cl, In, Cs, O, Pb, Co?<\/li>\n<li>Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: Br, Ca, Na, N, F, Al, Sn, S, Cd?<\/li>\n<li>Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>P<\/li>\n<li>Mg<\/li>\n<li>Al<\/li>\n<li>O<\/li>\n<li>Cl<\/li>\n<li>Cs<\/li>\n<\/ol>\n<\/li>\n<li>Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>I<\/li>\n<li>Sr<\/li>\n<li>K<\/li>\n<li>N<\/li>\n<li>S<\/li>\n<li>In<\/li>\n<\/ol>\n<\/li>\n<li>Write the electron configuration for each of the following ions:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>As<sup>3\u2013 <\/sup><\/li>\n<li>I<sup>\u2013 <\/sup><\/li>\n<li>Be<sup>2+ <\/sup><\/li>\n<li>Cd<sup>2+ <\/sup><\/li>\n<li>O<sup>2\u2013 <\/sup><\/li>\n<li>Ga<sup>3+\u00a0<\/sup><\/li>\n<li>Li<sup>+\u00a0<\/sup><\/li>\n<li>N<sup>3\u2013\u00a0<\/sup><\/li>\n<li>Sn<sup>2+\u00a0<\/sup><\/li>\n<li>Co<sup>2+\u00a0<\/sup><\/li>\n<li>Fe<sup>2+\u00a0<\/sup><\/li>\n<li>As<sup>3+<\/sup><\/li>\n<\/ol>\n<\/li>\n<li>Write the electron configuration for the monatomic ions formed from the following elements (which form the greatest concentration of monatomic ions in seawater):\n<ol style=\"list-style-type: lower-alpha;\">\n<li>Cl<\/li>\n<li>Na<\/li>\n<li>Mg<\/li>\n<li>Ca<\/li>\n<li>K<\/li>\n<li>Br<\/li>\n<li>Sr<\/li>\n<li>F<\/li>\n<\/ol>\n<\/li>\n<li>Write out the full electron configuration for each of the following atoms and for the monatomic ion found in binary ionic compounds containing the element:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>Al<\/li>\n<li>Br<\/li>\n<li>Sr<\/li>\n<li>Li<\/li>\n<li>As<\/li>\n<li>S<\/li>\n<\/ol>\n<\/li>\n<li>From the labels of several commercial products, prepare a list of six ionic compounds in the products. For each compound, write the formula. (You may need to look up some formulas in a suitable reference.)<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q614212\">Selected Answers<\/span><\/p>\n<div id=\"q614212\" class=\"hidden-answer\" style=\"display: none\">\n<p>1. The protons in the nucleus do not change during normal chemical reactions. Only the outer electrons move. Positive charges form when electrons are lost.<\/p>\n<p>3. P, I, Cl, and O would form anions because they are nonmetals. Mg, In, Cs, Pb, and Co would form cations because they are metals.<\/p>\n<p>5. The\u00a0predicted charges are as follows:<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>P<sup>3\u2013<\/sup><\/li>\n<li>Mg<sup>2+<\/sup><\/li>\n<li>Al<sup>3+<\/sup><\/li>\n<li>O<sup>2\u2013<\/sup><\/li>\n<li>Cl<sup>\u2013<\/sup><\/li>\n<li>Cs<sup>+<\/sup><\/li>\n<\/ol>\n<p>7. The correct electron configurations are<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[Ar] 3<em>d<\/em><sup>10<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\n<li>[Kr] 4<em>d<\/em><sup>10<\/sup>5<em>s<\/em><sup>2<\/sup>5<em>p<\/em><sup>6<\/sup><\/li>\n<li>1<em>s<\/em><sup>2<\/sup><\/li>\n<li>[Kr] 4<em>d<\/em><sup>8<\/sup><\/li>\n<li>[He] 2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup><\/li>\n<li>[Ar] 3<em>d<\/em><sup>10<\/sup><\/li>\n<li>1<em>s<\/em><sup>2<\/sup><\/li>\n<li>[He] 2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup><\/li>\n<li>[Kr] <em>d<\/em><sup>10<\/sup>5<em>s<\/em><sup>2<\/sup><\/li>\n<li>[Ar] 3<em>d<\/em><sup>7<\/sup><\/li>\n<li>[Ar] 3<em>d<\/em><sup>6<\/sup><\/li>\n<li>[Ar] 3<em>d<\/em><sup>10<\/sup>4s<sup>2<\/sup><\/li>\n<\/ol>\n<p>9.\u00a0The correct electron configurations are<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>1<\/sup>; Al<sup>3+ <\/sup>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup><\/li>\n<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>5<\/sup>; 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\n<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup>5<em>s<\/em><sup>2<\/sup>; Sr<sup>2+ <\/sup>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\n<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>1<\/sup>; Li<sup>+<\/sup> 1<em>s<\/em><sup>2<\/sup><\/li>\n<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>3<\/sup>; 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup>3<em>d<\/em><sup>10<\/sup>4<em>s<\/em><sup>2<\/sup>4<em>p<\/em><sup>6<\/sup><\/li>\n<li>1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>4<\/sup>; 1<em>s<\/em><sup>2<\/sup>2<em>s<\/em><sup>2<\/sup>2<em>p<\/em><sup>6<\/sup>3<em>s<\/em><sup>2<\/sup>3<em>p<\/em><sup>6<\/sup><\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n<h2>Glossary<\/h2>\n<p><strong>inert pair effect:\u00a0<\/strong>tendency of heavy atoms to form ions in which their valence <em>s<\/em> electrons are not lost<\/p>\n<p><strong>ionic bond:\u00a0<\/strong>strong electrostatic force of attraction between cations and anions in an ionic compound<\/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-1742\">\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":3,"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-1742","chapter","type-chapter","status-publish","hentry"],"part":3009,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/1742","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":16,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/1742\/revisions"}],"predecessor-version":[{"id":5990,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/1742\/revisions\/5990"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/parts\/3009"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapters\/1742\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/media?parent=1742"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/pressbooks\/v2\/chapter-type?post=1742"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/contributor?post=1742"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-chem-atoms-first\/wp-json\/wp\/v2\/license?post=1742"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}