Question

why atomic radius goes on decreasing while going from left to right in period​

Answer 1

atomic radius goes on decreasing while we go from left to right in a period because due to increase in protons and atomic number the nuclear force of attraction is increased as a result the electrons comes closer to the nucleus and atomic radius become decrease

Answer 2

When we go left to right in a period the outer shell remains same but an electron is added to every succeeding element.

To hold the extra electron the atomic nucleus exerts an extra nuclear force.

Due to this strong nuclear force the valence shell is more attracted towards the nucleus and size of atom decreases.

so atomic radius also decreases.