How do I write #Sn(NO_3)_2# in Ionic formula?
You write Sn(NO₃)₂ as Sn²⁺, 2NO₃⁻.
The formula Sn(NO₃)₂ tells you that there are one Sn ion and two NO₃ ions in a formula unit.
The positive ions come first in the formula. So we have
Sn is not a metal from Group 1, 2, or 3, so the Periodic Table doesn’t help us. And NO₃ is a polyatomic ion. Again, the Periodic Table gives no help.
We have to think of some simple compound that contains NO₃. Possibilities are HNO₃ and NaNO₃. Both H and Na are in Group 1. They form +1 ions.
Since HNO₃ is neutral and H has a charge of +1, NO₃ must have a charge of -1. The formula of the ion is NO₃⁻.
Sn(NO₃)₂ contains two NO₃⁻ ions, for a total charge of -2. The Sn ion must then have a charge of +2. We write its symbol as Sn²⁺.
The ionic formulation of Sn(NO₃)₂ is Sn²⁺, 2NO₃⁻.