Question

How do you name `MgCl_2`?

Answer 1

Magnesium chloride

Explanation:

Magnesium is in group II and will always form a 2+ ion when reacting. Equally, chorine is I group VII and will tend to gain one electron from a metal to form a 1- ion. `MgCl_"2"` is therefore the only possible formula for magnesium chloride.

Compare this to iron chloride. Iron can form a 2+ or 3+ ion, therefore you must make a difference in naming `FeCl_2=` iron(II) chloride and `FeCl_3=` iron(III) chloride.