Question

which structure is most like to be an exception to the octet rule?\
\\(\bigcirc\\) \\(\ce{sf4}\\)\
\\(\bigcirc\\) \\(\ce{ch3f}\\)\
\\(\bigcirc\\) \\(\ce{ccl4}\\)\
\\(\bigcirc\\) \\(\ce{pcl3}\\)

Explanation:

Step1: Recall the octet rule

The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable electron configuration with 8 valence electrons (except for hydrogen and helium).

Step2: Analyze each molecule

• \( \text{SF}_4 \): Sulfur (S) is in period 3, so it can have an expanded octet (more than 8 valence electrons). Sulfur in \( \text{SF}_4 \) has 10 valence electrons (5 bonding pairs: 4 with F and 1 lone pair), violating the octet rule.
• \( \text{CH}_3\text{F} \): Carbon (C) has 4 valence electrons, forming 4 bonds (3 with H, 1 with F), so it has 8 valence electrons (satisfies octet).
• \( \text{CCl}_4 \): Carbon forms 4 bonds with Cl, each bond contributing 2 electrons to C's valence shell, so C has 8 electrons (satisfies octet).
• \( \text{PCl}_3 \): Phosphorus (P) has 5 valence electrons, forming 3 bonds with Cl (3×2 = 6 electrons) and 1 lone pair (2 electrons), so total 8 valence electrons (satisfies octet).

Answer:

\( \text{SF}_4 \) (the first option: \( \text{SF}_4 \))