When a phosphorus atom is converted to a phosphide ion, what happens to the number of unpaired electrons and the total number of electrons around the phosphorus?

The transformation of a phosphorus atom into a phosphide ion results in significant changes to its electronic configuration. Phosphorus, as a neutral atom, has 15 electrons, distributed as 1s² 2s² 2p⁶ 3s² 3p³. The three electrons in the 3p orbital are unpaired.

When phosphorus gains three additional electrons to become a phosphide ion (P³⁻), these electrons fill the 3p orbital. This leads to all the electrons in the 3p orbital being paired. As a result, the number of unpaired electrons decreases to zero.

Moreover, the total number of electrons surrounding the phosphorus atom increases from 15 to 18, corresponding to the acquisition of three additional electrons to form the phosphide ion. This increase in electron count is what transforms phosphorus into a negatively charged ion, stabilizing its electronic structure.

To summarize, during the conversion of phosphorus to a phosphide ion, the number of unpaired electrons reduces to zero, while the total number of electrons around the atom increases, reflecting the gain of three electrons.