Question

What is the trend in ionic radius from left to right within a period

Answer 1

Atomic radius decreases from left to right in a period because the number of electron shells is same in all elements of a single period. However, the number of electrons and thus the number of protons continues to increase. This increases the size of the nucleus progressively which leads to an increasing nuclear pull on the same number of electron shells. Hence, the electron shells move closer to the nucleus progressively in a period from left to right hence decreasing the atomic radius.