Question

what is the charge of a nitride ion and how do we know this?
1- ; the polyatomic chart
3- ; the period that it is in
3- ; the group it is in
1-; the group it is in
3- ; the polyatomic chart

Explanation:

Nitrogen is in Group 15 (or 5A) of the periodic table. Non - metals in groups 15 (5A) gain 3 electrons to achieve a stable octet configuration, forming an ion with a 3 - charge (nitride ion, $\ce{N^{3-}}$). The group number helps determine the charge of the ion (for non - metals, the charge is often $8 -$ group number; for group 15, $8 - 5=3$, so 3 - charge). Polyatomic chart is for polyatomic ions, and period doesn't determine the charge of a non - metal ion like this. So the correct option is the one with 3 - charge and the group it is in.

Answer:

3-; the group it is in