In two or more complete sentences describe how atomic radius changes as you move across a period in the periodic table and why.

When we move across the period from left to right then there is decrease in atomic radius.

This is due to increase in number of protons and electrons across a period. Since electrons are added in same energy level, therefore, they get pulled closer to the nucleus because of more number of protons which carry a positive charge.

As a result, there is shrinkage in size from left to right across the period.

The atomic radius of a chemical element is a measure of the size of its atom.

The atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

The atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.