Which of the following elements would most likely form an ion with a +2 charge?
si.
c.
mg.
na.
p.

Mg

Explanation:

Magnesium has a valency of +2

The correct answer to this is Mg.

Explanation:

Mg is the second element at the Periodic Table, down Be. As its the oxidation number is 2, it can release two electrons to form compounds. Not like C that is tetravalent, or Na that is a monovalent element (1e-). Si, as C has 4 oxidation states, and phosphorus can lose or get 3 e- (for example PCl3), also get 5e- (for example  P2O5)

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

i do not get it   at all