Question

Define atomic radius of an isolated atom. How does the atomic size vary in a period of the periodic table?

Answer 1

Atomic radius is:

1. For an atom, atomic radius is defined as the distance of the outermost shell to the nucleus of that atom.
2. For non-metals, it is defined as half the distance of the two nuclei covalently bonded together by a single bond.
3. For metals, it is defined as half the distance of the two nuclei of the adjacent metals in a metallic crystal.

The atomic size of a period varies as:

1. On moving left to right along a period, the number of shells remain same but the number of electrons increases.
2. The increase in electrons leads to increase of effective nuclear charge, this increase in nuclear charge decreases the atomic size of the elements.
3. Therefore, the atomic size decreases along the period.