Răspuns:
Al- aluminiu
Z=13, A=27
A=Z+n
27=13+n
n=27-13
n=14
13e, 13p, 14n
K - potasiu
Z=19, A=39
39=19+n
n=39-19
n=20
19e, 19p, 20n
Ca- calciu
Z=20, A=40
40=20+n
n=40-20
20e, 20p, 20n
O - oxigen
Z=8, A=16
16=8+n
n=16-8
n=8
8e, 8p, 8n
Explicație:
