Răspuns:
Na natriu
Z=11, A=23
11e, 11p, 12n
K potasiu
Z=19, A=39
19e, 19p, 20n
Ca calciu
Z=20, A=40
20e, 20p, 20n
Mg magneziu
Z=12, A=24
12e, 12p, 12n
Cl clor
Z=17, A=35,5
17e,17p,18n
O oxigen
Z=8, A=16
8e,8p,8n
S sulf
Z=16, A=32
16e,16p,16n
P fosfor
Z=15,A=31
15e,15p,16n