Question

Complete the following suitably:

In any vertical column of elements in a subgroup of the Periodic Table, as you go from top to bottom.

The ionization potential ______.

Answer 1

• Ionization energy or ionization potential is the quantity of heat that must be supplied to eliminate the outermost electron from an isolated and neutral gaseous atom of any element.
• The general equation for the ionization of element X is:

$\mathrm{X}\left(\mathrm{g}\right)\to {\mathrm{X}}^{+}\left(\mathrm{g}\right)+{\mathrm{e}}^{-}$

• In the case of a group or column, the first ionization energy decreases down the Group in the periodic table due to more increase in the atomic size than decrease in effective nuclear charge down the Group.
• As atomic size increases down the Group in the periodic table, the electrons are more loosely held by the atomic nucleus due to the increase in distance between the valence electrons and nucleus. Hence, less energy is sufficient enough to eliminate the outermost electron, and therefore, ionization energy decreases down the Group.
• Example, Fluorine (F) and Chlorine (Cl) both belong to the same Group (Group 17) but Fluorine lies above Chlorine in the group. Therefore, the ionization energy or potential of Fluorine is higher than Chlorine.
• Hence, the ionization potential decreases.