Atomic Radius Definition

Chemistry Glossary Definition of Atomic Radius

The atomic radius is used to describe the size of an atom.
The atomic radius is used to describe the size of an atom. Getty Images

Atomic Radius Definition

The atomic radius is a term used to describe the size of the atom, but there is no standard definition for this value. Atomic radius may refer to the ionic radius, covalent radius, metallic radius, or van der Waals radius.

In all cases, the size of the atom is dependent on how far out the electrons extend. The atomic radius for an element tends to increase as one goes down an element group.

The electrons become more tightly packed as you move across the periodic table, so while there are more electrons for elements of increasing atomic number, the atomic radius actually may decrease.