What is the ground-state electron configuration of boron (B, atomic number 5) using simplified orbital notation?

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

Answer: (B)

Verified step by step guidance

1. Identify the atomic number of boron, which is 5. This means boron has 5 electrons to place in orbitals according to the Aufbau principle.
2. Recall the order in which orbitals are filled: first the 1s orbital, then the 2s orbital, and then the 2p orbitals.
3. Fill the 1s orbital with 2 electrons, since it can hold a maximum of 2 electrons. This gives us \$1\,s^{2}$.
4. Next, fill the 2s orbital with 2 electrons, also fully occupying it. This adds \$2\,s^{2}$ to the configuration.
5. Finally, place the remaining 1 electron in the 2p orbital, which can hold up to 6 electrons. This completes the configuration as \$2\,p^{1}$.