Аннотация
The possible specified formulation: properties of chemical elements and their compound are in periodic dependence on periodically renewing (repeated) external electronic configuration (shells) of atoms at sequential increase of a nucleus charge of elements atom. Having designated the similar periods ( 1 – I; 2,3 – II; 4,5 – III and 6,7 – IV ) Pn, we offer mathematical expression PL: Z = 2 pn2(n = I; II; III; IV).