The Periodic Table


Learning Objective

  • Identify the common periodic trends that can be deduced from the periodic table of elements

Key Points

    • The periodic table lists all the elements, with information about their atomic weights, chemical symbols, and atomic numbers.
    • The arrangement of the periodic table leads us to visualize certain trends among the atoms.
    • The vertical columns (groups) of the periodic table are arranged such that all its elements have the same number of valence electrons. All elements within a certain group thus share similar properties.


  • periodA horizontal row in the periodic table, which signifies the total number of electron shells in an element’s atom.
  • atomic numberThe number, equal to the number of protons in an atom, that determines its chemical properties. Symbol: Z
  • groupA vertical column in the periodic table, which signifies the number of valence shell electrons in an element’s atom.

Element Symbols

The periodic table is structured as an 18 X 7 grid, positioned above a smaller double row of elements. The periodic table only lists chemical elements, and includes each isotope of each element within one cell. In the typical periodic table, each element is listed by its element symbol and atomic number. For example, “H” denotes hydrogen, “Li” denotes lithium, and so on. Most elements are represented by the first letter or first two letters of their English name, but there are some exceptions. Two notable exceptions include silver and mercury. The symbol for silver is “Ag” from Latin argentum, which means “gray” or “shining.” The symbol for mercury is “Hg” from the Latinized Greek hydrargyrum, which means “water-silver.” Many periodic tables include the full name of element as well and color-code the elements based on their phase at room temperature (solid, liquid, or gas).

The periodic tableThe periodic table is a tabular display of all the chemical elements. The atoms are grouped in order of increasing atomic number.

Rows and Periods

The element symbol is always almost accompanied by other information such as atomic number and atomic weight. Atomic number describes the number of protons in one atom of that element. For example, an atom of oxygen contains 8 protons. Elements are listed in order of increasing atomic number from left to right. Each row of the periodic table is called a period and each column of the periodic table is called a group (or family). Some groups have specific names like the halogens or noble gases. Elements within the same period or group have similar properties.

Determining Chemical Properties using the Periodic Table

Chemical properties of each element are determined by the element’s electronic configuration, and particularly by its outermost valence electrons. An element’s location in the periodic table is largely dependent on its electrons; the number of valence shell electrons determines its group, and the type of orbital in which the valence electrons lie in determines the element’s block. In addition, the total number of electron shells an atom determines which period it belongs to. Because of its structure, the periodic table has become an extremely useful tool for assessing and predicting elemental and chemical trends.

Chemistry 3.1 Introduction to the Periodic Table – YouTubeAn introduction to the periodic table which identifies metals, ,nonmetals, and metalloids by location and compares and contrasts the physical properties of metals and nonmetals.