How come original charges disappear when ionic chemical formulas are calculated? For example, Na+ and O2- become Na2O or Al3+ and Cl- become AlCl3

Question

How come original charges disappear when ionic chemical formulas are calculated? For example, 

Na+ and O2- become Na2O or Al3+ and Cl- become AlCl3

Answer 1

Hi Elisheva,

When you are writing the formula for an ionic chemical, the goal is for the ions to balance in proportions that make an overall neutral compound.

In the case of Na⁺ and O^2-, since O has a charge of -2, you need 2 Na ions (with a charge of +1 each) to make a neutral compound. 2(+1) = 1(-2).

For Al³⁺ and Cl^-, you need a ratio of 1 Al³⁺ : 3 Cl^-.

Hope this helps. If not, feel free to reach out and we can schedule a time to keep working on this.