# What is the molecular formula of sodium phosphate?

Dec 22, 2015

$N {a}_{3} P {O}_{4}$
This is so since sodium is in group $1$ so has a valency of $1 +$ while phosphate is a polyatomic ion of valency $3 -$ and thus we need $3$ sodium atoms for each $1$ phosphate ion, hence, $N {a}_{3} P {O}_{4}$.