notez elementul A cu Z e/mol
elementul B cu Z+1 e/mol
elementul C cu Z+2 e/mol
n,mol= N/N,A= 144,528X10²³ e /6,012X10²³ /e/mol=24 mol electroni
2mol(Z+Z+!+Z+2)=24mol
3Z+3=12========> Z= 3---> casuta 3 ->Li
Z+!=4----> casuta 4--> Be
Z+2=5----> casuta 5 ->B