Question

which of the following is the correct orbital diagram for o?a. 1s² 2s² 2p⁴b. 1s² 2s² 2p⁴c. 1s² 2s² 2p⁴d. 1s² 2s² 2p⁴c b a d

Explanation:

• Electron configuration of O: Oxygen has an atomic number of 8. Its electron configuration is \(1s^{2}2s^{2}2p^{4}\).
• Filling rules:
• Pauli exclusion principle: Each orbital can hold a maximum of 2 electrons with opposite spins. So, \(1s\) and \(2s\) orbitals (which are single - orbital subshells) are filled with 2 electrons of opposite spins.
• Hund's rule: For degenerate orbitals (like the three \(2p\) orbitals), electrons are filled singly first with parallel spins before pairing. For \(2p^{4}\), first, three electrons occupy each of the three \(2p\) orbitals with parallel spins, and then the fourth electron pairs up in one of the \(2p\) orbitals.

• Analysis of options:
• Option A: Follows the Pauli exclusion principle (\(1s^{2}\) and \(2s^{2}\) are correctly filled with 2 electrons of opposite spins) and Hund's rule (\(2p^{4}\) has two unpaired electrons with parallel spins after one orbital is paired).
• Option B: Violates the Pauli exclusion principle in the \(2p\) orbital (two electrons in the same \(2p\) orbital have parallel spins).
• Option C: Violates the Pauli exclusion principle in \(1s\) and \(2s\) (each should have 2 electrons, but here they have 1).
• Option D: Violates the Pauli exclusion principle in \(2s\) (it should have 2 electrons of opposite spins, but here it has 1).

Answer:

A.