Questions: Which of the following molecules has a valid Lewis structure that cannot be drawn without violating the octet rule? SbF3 NF3 IF3 PF3

Solution Steps

The octet rule states that atoms tend to form compounds in ways that give them eight valence electrons, achieving a noble gas electron configuration. However, there are exceptions, particularly for elements in period 3 and beyond, which can have expanded octets.

• $\mathrm{SbF}_{3}$: Antimony (Sb) is in period 5 and can have an expanded octet. It can accommodate more than 8 electrons.
• $\mathrm{NF}_{3}$: Nitrogen (N) is in period 2 and strictly follows the octet rule. It forms a valid Lewis structure with 8 electrons.
• $\mathrm{IF}_{3}$: Iodine (I) is in period 5 and can have an expanded octet. It can accommodate more than 8 electrons.
• $\mathrm{PF}_{3}$: Phosphorus (P) is in period 3 and can have an expanded octet, but typically forms compounds with 8 electrons in its valence shell.

Among the given molecules, $\mathrm{IF}_{3}$ is the one that cannot be drawn without violating the octet rule because iodine can have more than 8 electrons in its valence shell due to its ability to expand its octet.

Final Answer