Concept: Unpaired electrons are found by looking at the partially filled subshells of an atom's ground-state electronic configuration.
Formula: None required.
Solution: - Let's evaluate the ground state configurations for the options:
- \( Z=6 \) (Carbon): \( 1s^2, 2s^2, 2p^2 \). Two unpaired electrons in \( 2p \).
- \( Z=14 \) (Silicon): \( [Ne] 3s^2, 3p^2 \). Two unpaired electrons in \( 3p \).
- \( Z=22 \) (Titanium): \( [Ar] 4s^2, 3d^2 \). Two unpaired electrons in \( 3d \).
- \( Z=26 \) (Iron): \( [Ar] 4s^2, 3d^6 \). The \( 3d \) subshell has 5 orbitals. Placing 6 electrons means one orbital gets a pair, leaving exactly 4 singly occupied (unpaired) orbitals.
- Thus, Iron (\( Z=26 \)) has four unpaired electrons.
Why other options are incorrect: The other listed elements all have exactly two unpaired electrons.
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