Which of the following represents the electron configuration of P^{3-}?

• A. 1s^2 2s^2 2p^6 3s^2 3p^1
• B. 1s^2 2s^2 2p^6 3s^2 3p^5
• C. 1s^2 2s^2 2p^6 3s^2 3p^3
• D. 1s^2 2s^2 2p^6 3s^2 3p^6

Answer: (D)

Verified step by step guidance

1. Identify the atomic number of phosphorus (P), which is 15. This means a neutral phosphorus atom has 15 electrons.
2. Write the electron configuration for neutral phosphorus by filling orbitals in order of increasing energy: \$1s^2 2s^2 2p^6 3s^2 3p^3$.
3. Recognize that the ion P^{3-} has gained 3 extra electrons, so the total number of electrons is \$15 + 3 = 18$.
4. Add the 3 extra electrons to the neutral phosphorus configuration, filling the 3p orbital completely: \$3p^3 + 3 = 3p^6$.
5. Write the full electron configuration for P^{3-} as \$1s^2 2s^2 2p^6 3s^2 3p^6$, which corresponds to the electron configuration of argon, a noble gas.