For Li2 to N2, how do the 2s orbitals combine according to molecular orbital theory?

In molecular orbital theory, when two atomic orbitals combine, they can form both bonding and anti-bonding molecular orbitals. In the case of the combination of 2s atomic orbitals from lithium atoms to nitrogen atoms, the interaction leads to the formation of a bonding molecular orbital and an anti-bonding molecular orbital.

The bonding molecular orbital is lower in energy compared to the original atomic orbitals, which stabilizes the molecule. This orbital allows for the sharing of electrons between the two nuclei, resulting in a stronger bond. Conversely, the anti-bonding orbital has higher energy and is destabilizing, and its formation implies that any electrons occupying this orbital would have the opposite effect, reducing the stability of the molecule.

For elements like lithium and nitrogen, it is typical for the 2s orbitals to form these two types of molecular orbitals due to their combination. While heavier elements can have more complex interactions, the basic outcome of one bonding and one anti-bonding orbital is consistent across these lighter elements in the periodic table. Thus, the conclusion that this combination results in one bonding and one anti-bonding orbital aligns well with molecular orbital theory.