Element/
ion
H
He
Li
Li +
C
N
N 3O
O 2Na
Na+
FMg
Mg2+
K+
Ca2+
Al3+
S2ClAr
Cu
Cu+
Cu2+
Br
Br Fe
Fe2+
Fe3+
Atomic
number
Mass
number
1
Number of
1
protons
1
electrons
1
neutrons
0
2
4
2
2
2
3
7
3
3
4
3
7
6
12
6
6
6
7
14
7
7
7
8
16
8
8
8
11
23
11
11
12
12
24
12
12
12
29
63.5
29
29
34.5
35
80
35
35
45
56
26
26
30
35
26
26