A = 2B
A-C = 4
C: K2e- L6e- => C = 8 = O, oxigen
=> A = 4+8 = 12 = Mg, magneziu
B = 12/2 = 6 = C, carbon
sarcina nucleara
A = +12
B = +6
C = +8
structura
A, Z=12, K2e- L8e- M2e-
B, Z=6, K2e- L4e-
C, Z=8, K2e- L6e-
nr. straturi complet acupate
A = 2 straturi (K si M)
B = 1 strat (K)
C = 1 strat (K)