Question

How does atomic radius change on moving left to right in periodic table?

Answer 1

The atomic size is determined by how far the last shell of electrons is away from the nucleus. Farther the last shell from nucleus, greater is the atom's size.

As we move from left to right across a period on a periodic table, the number of protons in the nucleus of the atom increases.

The greater the number of protons, the more will be the force of attraction between between the protons and the electrons, i.e. the protons in the nucleus of the atom will pull the electrons closer with a greater force.

In short, we can also say that the nuclear charge increases as we move from left to right of a period

Since the last shell gets pulled closer, the atomic size also decreases.

Answer 2

Atomic radius decreases on moving from left to right.