Question

The number of non-bonding electrons present in the frontier molecular orbitals of HF is

• A. 10
• B. 4
• C. 6
• D. 8

Hint:

Lone pairs on atoms in a molecule contribute to non-bonding electrons in the frontier molecular orbitals.

Answer 1

The Correct Option is B

Step 1: Understanding frontier molecular orbitals.
The frontier molecular orbitals (FMOs) of a molecule consist of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). For HF, we need to count the electrons in the non-bonding orbitals, which are typically lone pair electrons.

Step 2: Analyzing the electron configuration.
- HF has a total of 8 valence electrons (7 from fluorine and 1 from hydrogen).
- Fluorine has 3 lone pairs, each contributing 2 electrons (6 electrons in total).
- The non-bonding electrons come from the fluorine lone pairs. There are 6 non-bonding electrons in the frontier orbitals.

Step 3: Conclusion.
The number of non-bonding electrons is 6, so the correct answer is (C).