# What is the atomic size of an atom?

Atomic and Ionic Radii- The radius of an atom may be defined as the distance between the center of the atom and the outermost shell of electrons. However, not an absolute definition of atomic size since different environments may have considerable effects on the atomic sizes. Distance between the center of the nucleus and the outermost shell of electrons is called atomic radius.

• Covalent radius is half the internuclear distance between two atoms of the elements held by a single covalent bond.
• Van der Waals radius is half of the internuclear distance between two nearest atoms belonging to two adjacent molecules in solid-state.
• Metallic radius is half the internuclear distance between two nearest atoms in the metallic lattices.
• Atomic size increases as they pass from the top to the bottom of the periodic table.