Question

what is the name of the compound whose formula is na3p?
a) sodium phosphite
b) sodium phosphate
c) sodium(iii) phosphide
d) sodium phosphide

Explanation:

• Sodium (\(Na\)) is a metal cation with a charge of \(+1\).
• Phosphorus (\(P\)) in this compound is in the phosphide form (\(P^{3 -}\)).
• When naming ionic compounds, we name the cation first (sodium) and then the anion. The suffix for the anion \(P^{3 -}\) is “-ide”. So, the compound \(Na_3P\) is named sodium phosphide.
• Sodium phosphite (\(Na_3PO_3\)) and sodium phosphate (\(Na_3PO_4\)) have poly - atomic phosphate or phosphite ions (\(PO_3^{3 -}\) or \(PO_4^{3 -}\)). Sodium(III) phosphide is an incorrect naming as sodium has a fixed charge (\(+1\)) and we don't use Roman numerals for it in ionic compound naming.

Answer:

D. sodium phosphide