What is the ground-state electron configuration of phosphorus (P), atomic number 15?

• A. $1^{s}22^{s}22^{p}63^{s}23^{p}5$
• B. $1^{s}22^{s}22^{p}63^{s}13^{p}4$
• C. $1^{s}22^{s}22^{p}63^{s}23^{p}3$
• D. $1^{s}22^{s}22^{p}63^{s}23^{p}6$

Answer: (C)

Verified step by step guidance

1. Identify the atomic number of phosphorus, which is 15. This means phosphorus has 15 electrons to place in its electron configuration.
2. Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, and so on.
3. Fill the orbitals in order, starting with the lowest energy level: place 2 electrons in 1s, 2 electrons in 2s, and 6 electrons in 2p. This accounts for 10 electrons so far.
4. Next, place 2 electrons in the 3s orbital, bringing the total to 12 electrons placed.
5. Finally, place the remaining 3 electrons in the 3p orbital to reach a total of 15 electrons, completing the ground-state electron configuration for phosphorus.