Question

What is Atomic Radius ?

Answer 1

Atomic radius is the distance from the center of the atom to the outermost electron shel. Usually the shell is defined by the area of 90% probability of containing the electron. The radius will get bigger if the atom becomes an anion. If it becomes a cation it will shrink. The general rule is that radius get smaller when going from the bottom left to the top right of the periodic table. There is an exception when going from the alkaline metals to the transition metals on the sizes though.