What is the electron configuration for a phosphorous anion with a charge of #-2#?
Your starting point here will be the electron configuration of a neutral phosphorus atom.
Therefore, the electron configuration of a neutral phosphorus atom will show
#"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
Therefore, the electron configuration of the
#"P"^(2-): 1s^2 2s^2 2p^6 3s^2 3p^5#
Using the noble gas shorthand notation, you will get
#"P"^(2-): ["Ne"] 3s^2 3p^5#