What phosphorous number of electrons gained or lost to fill outer energy level?

Phosphorus has an atomic number of 15, with an electron configuration of 1s² 2s² 2p⁶ 3s² 3p³. To achieve a full outer energy level (which can hold 8 electrons), phosphorus typically gains 3 electrons. This allows it to complete its p orbital, forming a stable anion (P³⁻). Alternatively, it can lose 5 electrons, but gaining 3 is the more common approach for stability.