Which is the correct ground-state electron configuration for phosphorus (P), atomic number 15?

• A. $1s{2}^{}2s{2}^{}2p{6}^{}3s{1}^{}3p{4}^{}$
• B. $1s{2}^{}2s{2}^{}2p{6}^{}3s{2}^{}3p{6}^{}$
• C. $1s{2}^{}2s{2}^{}2p{6}^{}3s{2}^{}3p{5}^{}$
• D. $1s{2}^{}2s{2}^{}2p{6}^{}3s{2}^{}3p{3}^{}$

Answer: (D)

Verified step by step guidance

1. Identify the atomic number of phosphorus (P), which is 15. This means phosphorus has 15 electrons in its neutral ground state.
2. Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, then 3p.
3. Fill the orbitals with electrons following the maximum capacity of each: 1s can hold 2 electrons, 2s can hold 2, 2p can hold 6, 3s can hold 2, and 3p can hold 6.
4. Add electrons sequentially until you reach 15 total electrons: fill 1s with 2, 2s with 2, 2p with 6, 3s with 2, and then place the remaining electrons in 3p orbitals.
5. Write the electron configuration using the notation \$1\text{s}^2 2\text{s}^2 2\text{p}^6 3\text{s}^2 3\text{p}^x\(, where \)x$ is the number of electrons left after filling the previous orbitals, which corresponds to phosphorus's valence electrons.