Question

Why is `Ca(NO_3)_2` a ionic bond? I thought all of them are nonmetals so it should be a covalent bond?

Answer 1

The nitrate ion, `NO_3^(-)` is a discrete species.....

And calcium is a METAL......

Explanation:

You look at the Lewis formulation of nitrate, THREE of the four atoms bear formal charges....

`O=stackrel(+)N(-O^(-))_2-=NO_3^(-)`

We say that the nitrogen is quaternized and has donated its lone pair to an oxygen atom.....the charge is balanced by the tow oxygen atoms that bear a formal negative charge....

Calcium is in Group 2 of the Periodic Table, so it typically forms `Ca^(2+)` upon oxidation.....

`Ca(s) +DeltararrCa^(2+) + 2e^(-)`

The salt balances charge....and so `Ca^(2+) + 2xxNO_3^(-)` gives...

`Ca(NO_3)_2`...........as the salt of a metal and an acid.