Question

Which of the following molecules does not obey octet rule?

• A. \( \text{N}_2 \)
• B. NaCl
• C. \( \text{Cl}_2 \)
• D. \( \text{SF}_6 \)

Hint:

The octet rule can be violated by elements in periods 3 or higher, as they have access to d-orbitals and can accommodate more than 8 electrons in their valence shell.

Answer 1

The Correct Option is D

Step 1: Understanding the octet rule.
The octet rule states that atoms tend to form molecules in which they have eight electrons in their valence shell. However, some molecules do not follow this rule, such as those involving elements from periods 3 or higher that can have more than 8 electrons in their valence shell.
Step 2: Analyzing the options.
(A) \( \text{N}_2 \): Correct, nitrogen obeys the octet rule with 8 electrons in its valence shell.
(B) NaCl: Correct, sodium and chlorine both obey the octet rule.
(C) \( \text{Cl}_2 \): Correct, chlorine obeys the octet rule with 8 electrons in its valence shell.
(D) \( \text{SF}_6 \): Incorrect — \( \text{SF}_6 \) violates the octet rule, as sulfur has 12 electrons in its valence shell.
Step 3: Conclusion.
The correct answer is (D) \( \text{SF}_6 \).