Question

Atomic size ___ from left to right in a period.

Answer 1

Atomic size gradually decreases as you go from left to right in a period. This is because, within a period, all electrons are added to the same shell. However, at the same time, protons are being added to the nucleus, making it more positively charged. The effect of an increase in the number of protons number is greater than that of the increase in the number of electrons; therefore, there is a greater nuclear attraction. This means that the nucleus attracts the electrons more strongly, pulling the atom's shell closer to the nucleus. The valence electrons are held closer towards the nucleus of the atom. As a result, the atomic radius decreases.