Question

Atomic size in period decreases, why?​

Answer 1

Answer:

The force of attraction between nuclei and electrons increases, the size of the atoms decreases.

Explanation:

Within a period, protons are added to the nucleus as electrons are being added to the same principal energy level. These electrons are gradually pulled closer to the nucleus because of its increased positive charge. Since the force of attraction between nuclei and electrons increases, the size of the atoms decreases.