Molecular Orbital Diagram of HF2-

Introduction
The molecular orbital (MO) theory is used to describe the bonding and properties of molecules. In this theory, atomic orbitals (AOs) combine to form molecular orbitals. The molecular orbital diagram provides a visual representation of the energy levels and electron occupancy of these orbitals.

Formation of HF2-
HF2- is formed by the combination of two HF molecules, where one of the HF molecules donates an electron to form the negatively charged ion.

Molecular Orbital Energy Levels
The molecular orbital diagram of HF2- can be constructed by considering the energy levels of the atomic orbitals involved in the formation of the molecule. The fluorine atom has 2s and 2p orbitals, while the hydrogen atom has only a 1s orbital.

Atomic Orbitals
- The 1s orbital of hydrogen combines with the 2p orbitals of fluorine to form molecular orbitals.
- The 2s orbital of fluorine remains non-bonding.

Molecular Orbitals
- The combination of the 1s orbital of hydrogen and the 2p orbitals of fluorine results in the formation of three molecular orbitals: σ, π, and π*.
- The σ orbital is lower in energy than the π orbitals.
- The σ orbital is a bonding orbital, while the π orbitals are both bonding and antibonding.
- The π* orbital is an antibonding orbital.

Filling of Electrons
- The σ orbital is filled with two electrons, one from each hydrogen atom.
- The π bonding orbital is filled with two electrons, one from each hydrogen atom.
- The remaining electron is placed in the π* antibonding orbital.

Molecular Orbital Diagram
The molecular orbital diagram of HF2- can be represented as follows:

```
σ
↑↓
π* ↑↓ π
```

- The σ orbital is the lowest in energy and is fully occupied with two electrons.
- The π bonding orbital is filled with two electrons.
- The π* antibonding orbital contains a single electron.

Conclusion
In summary, the molecular orbital diagram of HF2- consists of a σ bonding orbital, a π bonding orbital, and a π* antibonding orbital. The σ and π orbitals are filled with two electrons each, while the π* orbital contains one electron. This diagram provides a visual representation of the energy levels and electron occupancy in the molecule.