Introduction to the Periodic Table

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Robert Boyle first defined an element as a substance that could not be broken down into simpler materials by chemical means in the 1600's, and ever since then more and more has been learnt about the elements. The periodic table came about to explain the order between them and the connection they have. This is seen most clearly through the similar properties of connected elements.

The periodic table follows the principle that when elements are arranged in order of increasing atomic number the properties of the elements vary periodically. The atomic number of an atom is the number of protons in the nucleus of that atom. This differs from the Mass number which is the sum of the number of protons and neutrons in the nucleus of an atom of that element

Most periodic tables are seen in terms of atomic number and atomic mass number with the element name but periodic tables are also used in terms of electronegativity values (the relative attraction of an atom for shared pairs of electrons in a covalent bond), and ionisation energies (the minimum amount of energy needed to remove the most loosely held electron from an atom).

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