What is the electron configuration for a phosphorous anion with a charge of ##-2##?

##"P"^(2-): ["Ne"] 3s^2 3p^5##

Your starting point here will be the of a neutral phosphorus atom.

Phosphorus, ##"P"##, is located in period 3, group 15 of the , and has an equal to ##15##. This means that a neutral phosphorus atom will have ##15## electrons surrounding its nucleus.

Therefore, the of a neutral phosphorus atom will show ##15## electrons

##"P: " 1.2^2 2s^2 2p^6 3s^2 3p^3##

Now, in order for the phosphorus atom to become a phosphorus anion, it must gain two electrons. Since the 3p-subshell only holds ##3## electrons in the neutral atom, these incoming electrons will be placed there.

Therefore, the electron configuration of the ##"P"^(2-)## anion will be

##"P"^(2-): 1s^2 2s^2 2p^6 3s^2 3p^5##

Using the , you will get

##"P"^(2-): ["Ne"] 3s^2 3p^5##