Magnesium Nitrate Formula: Mg(NO3)2

[Geekchick]

Homework Statement

Write the formula for magnesium nitrate.

2. The attempt at a solution

Okay, so I get that I have to list the cation first and then the anion. I also understand that I have to take the charges into consideration and end up with a neutral compound. My question is why is the formula for magnesium nitrate

Mg(NO₃)₂

If Mg⁺² N^-3 and O^{3}_{-2} to me it seems that O would have a total charge of -6 add the N charge and that's -9 while Mg has just +2. So this doesn't seem to equal out, plus I don't understand where the subscript 2 is from.

Thanks for the help sorry if this is a simple question.

 

[symbolipoint]

NITRATE has a charge of negative one;
Nitrate has a charge of -1.

Yes the oxygens each have associated charge of -2 each.

One Mg ion has charge +2, so it needs 2 nitrates.

 

[Geekchick]

Oh thanks!

 

[symbolipoint]

Could we put in a chart or a table in a message? Someone could clarify things like charge accounting for an ion very nicely using a table. I see no tags for creating a chart or table.