Question

The atomic size of lithium is _____ than that of sodium.

• A. greater
• B. smaller

Answer 1

Step-1:

Atomic radii is the distance of the electrons in the outermost from the atomic nucleus. It increases from top to bottom in a group and decreases from left to right in a period but is highest for a noble gas.

Step-2:

The Sodium ($\mathrm{Na}$) and Lithium ($\mathrm{Li}$) belongs to group 1. The atomic radius of Lithium is smaller than Sodium. Sodium, the outermost shell is M-shell (n=3) but in Lithium the outermost shell is L-shell (n=2). Thus , the increase in number of shells increase the size of the atom in a group.

Final answer:

The atomic size of Lithium is smaller than that of Sodium.