Valence (chemistry)

Valence is a scientific term in chemistry to describe electrons in the outermost orbital. Valence electrons are used by atoms in chemical reactions and are generally the most important factor in determining which reactions can and cannot take place, especially in covalent bonding. In the American periodic table, the number of valence electrons one neutral atom has corresponds to its A group number.

See also: Valency (lists valence numbers for certain atoms)