Question

In what part of a Group would you expect the element to have the greatest metallic character and the largest atomic size?

Answer 1

• Metallic character is the ability of an atom to lose either one or more electrons to obtain a stable electronic configuration. The more easily an element loses electrons, the more metallic character it has. For example, Potassium $\left(\mathrm{K}\right)$, a metal, easily loses an electron $\left({\mathrm{e}}^{-}\right)$ to form Potassium ion $\left({\mathrm{K}}^{+}\right)$.

$\mathrm{K}+\mathrm{energy}\to {\mathrm{K}}^{+}+{\mathrm{e}}^{-}$

• In representative elements, the atomic size increases while the ionization energy decreases on moving down the Group in the periodic table. Due to an increase in the atomic size and consequently the decrease in ionization energy, the loss of electrons by the element becomes easy and therefore, the metallic character increases on moving from top to bottom in any Group.
• The atomic size of an atom is defined as the distance from the nucleus of that atom to its outermost shell. It is generally measured in angstroms $\left(\mathrm{A}°\right)$.
• In representative elements, the number of shells and effective nuclear charge both increase on moving from top to bottom in a Group. Since the increase in the number of shells is a more dominant factor than the rise in effective nuclear charge, the atomic size increases from top to bottom in any Group.
• For example, Fluorine (F) and Chlorine (Cl) both belong to the same Group (Group 17) but Fluorine lies above Chlorine in the group. Therefore, Chlorine is larger in size and has more metallic character than Fluorine.
• Hence, elements present at the bottom of any group have the maximum metallic character and atomic size.