# Zinc phosphide, Zn_3P_2, is often used as a rat poison. Phosphorus has 5 valence electrons. How many valence electrons does each zinc atom lose?

The phosphide anion is formally ${P}^{3 -}$..........
And the zinc cation is $Z {n}^{2 +}$. When the ions form a salt, clearly they form an electrically neutral species; and thus the formulation of the salt is $Z {n}_{3} {P}_{2}$. Each phosphorus atom formally possesses 8 valence electrons. The $4 {s}^{2}$ valence electrons on zinc are presumed to be ABSENT, and this centre is a ${d}^{10}$ dication.