How many electrons does a nitrogen atom need to gain in order to fill its outer (valence) shell?

• A. 5
• B. 2
• C. 1
• D. 3

Answer: (D)

Verified step by step guidance

1. Identify the atomic number of nitrogen, which is 7. This means a neutral nitrogen atom has 7 electrons.
2. Determine the electron configuration of nitrogen. The first shell (1s) holds 2 electrons, and the second shell (2s and 2p) holds the remaining 5 electrons.
3. Recognize that the outer (valence) shell for nitrogen is the second shell, which can hold up to 8 electrons in total (2 in 2s and 6 in 2p orbitals).
4. Calculate how many electrons nitrogen needs to gain to fill its valence shell by subtracting the current number of valence electrons (5) from the full shell capacity (8): \$8 - 5 = 3$.
5. Conclude that nitrogen needs to gain 3 electrons to complete its outer shell and achieve a stable octet configuration.