The particular reaction that represents the oxidation of Mg metal would be the following:
Mg => Mg+2 + 2e-
This is the half reaction of the oxidation of the magnesium metal, another charged species would need to receive it to become reduced or gain the 2 electrons lost.
Helium
Remember: electron filling of atomic shell ...
The element which have electron in the lowest quantum shell will have the smallest atomic radius\
He:1s1 (Helium)
H:1s2 (hydrogen)
