Multiple Choice
Which of the following is the correct electron configuration for a neutral phosphorus (P) atom?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following correctly represents the orbital diagram for arsenic (As, atomic number 33)?
A
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑↓ 4s: ↑↓ 3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 4p: ↑↓ ↑
B
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑↓ 4s: ↑↓ 3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 4p: ↑ ↑
C
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑↓ 4s: ↑↓ 3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 4p: ↑
D
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑↓ 4s: ↑↓ 3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 4p: ↑↓ ↑↓
Verified step by step guidance1
Determine the total number of electrons in arsenic (As) using its atomic number, which is 33. This means arsenic has 33 electrons to place in orbitals.
Recall the order of orbital filling based on the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, and then 4p orbitals.
Fill the orbitals in order, remembering that each s orbital can hold 2 electrons, each p orbital can hold 6 electrons (2 per each of the 3 p orbitals), and each d orbital can hold 10 electrons (2 per each of the 5 d orbitals).
Apply Hund's rule when filling the 4p orbitals: electrons will occupy empty orbitals singly before pairing up. Since arsenic has 33 electrons, after filling up to 3d orbitals, place the remaining electrons in the 4p orbitals with one electron in each of the first two 4p orbitals.
Verify that the total number of electrons placed equals 33 and that the electron configuration matches the expected pattern, especially focusing on the 4p orbitals to ensure correct representation of unpaired electrons.
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