1.The coordination number of a specified atom in a chemical species is the number of other atoms directly linked to that specified atom 2.In an inorganic coordination entity, the number of σ-bonds between ligands and the central atom. π-bonds are not considered in determining the coordination number, Orgaanilises keemias: vaadeldava aatomiga vahetult seotud teiste aatomite arv. Anorgaanilises keemias: tsentraalaatomi ja ligandide vaheliste σ-sidemete arv