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 ##Zn^(2+)##. When the ions form a salt, clearly they form an electrically neutral species; and thus the formulation of the salt is ##Zn_3P_2##. Each phosphorus atom formally possesses 8 . The ##4s^2## on zinc are presumed to be ABSENT, and this centre is a ##d^10## dication.