Atomic Radius

One half the distance between nuclei of atoms of the same element, when the atoms are bound by a single covalent bond or are in a metallic crystal.

The radius of atoms obtained from covalent bond lengths is called the covalent radius; the radius from interatomic distances in metallic crystals is called the metallic radius.

See also: Atom, Bond Length, Covalent Radius, Metallic Radius, Nucleus.