Answer to Question #145917 in General Chemistry for Erlimar

Question

Find the smallest number of each ion needed to get the same number of positive and negative charges. These
numbers are the subscripts of the ions in the final formula of the compound. An easy method to choose the
correct subscript is to criss- cross the charges of the ions:
Mg+2

Answer 1

Since the negative ion is not given, I want to teach you how this is done.

Suppose you have Cl^- as the anion;

Mg²⁺ Cl^-

It will take two of Cl^- to get a 2- charge to equalize the 2+ charge of Mg²⁺

Thus,

M²⁺ and 2Cl^- will give MgCl₂