A=19 F Z=9 nucleu 9 p,19-9=10 n
A=27 Al Z=13 nucieu 13 p,27-13=14 n
A=39 K Z=19 nucleu 19 p,39-19=20 n
A=32 S Z=16 nucleu 16 p,32-16=16 n
A=31 P Z=15 nucleu 15 p,31-15=16 n
A=56 Fe Z=26 nucleu 26 p,56-26=30 n
A=64 Cu Z=29 nucleu 29 p,64-29=35 n
A=55 Zn Z=30 nucleu 30 p,55-30=25 n