Question

What happens to the atomic size of elements on moving from top to bottom of a group?

Answer 1

In general, the atomic size of elements increases from top to the bottom within a group in the periodic table. In moving down a group, the nuclear charge increases with an increase in atomic number, but at the same time, newer and newer shells are being added. The number of the valence electrons remains the same. The effect of additional shells is more pronounced than the effect of increased nuclear charge. Consequently, the effective nuclear charge decreases down a group leading to an increase in atomic size.