(40; 19) К = (40; 20) Са + (0; -1) е (40; 19) К + (0; -1) е = (40; 18) Аr (1; 0) n = (0; -1) e + (1; 1) p (226; 88) Ra = (4; 2) He + (222; 86) Rn (14; 7) N + (4; 2) He = (17; 8) O + (1; 1) p