Electron capacity of a shell
What is the maximum number of electrons the n = 3 shell can hold?
Answer C: explanation for every choice
A
Eight is the octet, describing valence s and p electrons, not the full shell.
B
Nine is n², the number of orbitals in the shell. Each orbital holds two electrons.
C
Correct. A shell holds up to 2n² electrons: 2(3²) = 18, in the 3s, 3p, and 3d subshells.
D
32 is the capacity of the n = 4 shell.
TakeawayMaximum electrons per shell = 2n².
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp38.