se stie ca 1mol atomi..Na...... ... 6,023x10²³atomi(numarul lui Avogadro)
x.......................................12,046x10²³atomiNa
1mol at..Li...................6,023x10²³at
x.......................................18,069x10²³at
1mol atAl.................6,023x10²³at
x.................................30.115x10²³at
calculeaza x
el rezulta si din relatia niu=N/N,A(numarul lui Avogadro)