Final answer:
The bond order for the HF molecule is 1, representing a single covalent bond formed by the overlap of the hydrogen 1s and fluorine 2p orbitals according to Valence Bond Theory.
Step-by-step explanation:
The overlap of the hydrogen 1s orbital and the fluorine 2p orbital can be visualized to illustrate the bonding in an HF molecule. A bonding molecular orbital is formed when the hydrogen 1s and fluorine 2p orbitals constructively interfere with each other, which is lower in energy than the atomic orbitals. An antibonding molecular orbital results from the destructive interference and is higher in energy. To determine the bond order, we compare the number of electrons in the bonding and antibonding orbitals. For HF, there is one electron from hydrogen and one unpaired electron from the fluorine 2p orbital that combine to fill the bonding orbital, with no electrons in the antibonding orbital. Hence, the bond order of HF is calculated by subtracting the number of antibonding electrons from the bonding electrons and dividing by two. Since there are two electrons in the bonding orbital and none in the antibonding orbital, the bond order for HF is (2-0)/2 = 1, corresponding to a single covalent bond.
Using Valence Bond Theory, we can say the covalent bond in HF is the result of the overlap between the hydrogen's 1s orbital and the fluorine's 2p orbital, creating a stable molecular orbital where the electron pair is shared between the two atoms.