Is the bond in the molecular orbital energy level diagram of Li2 stable?

To determine whether the bond in the molecular orbital energy level diagram of Li2 is stable, we need to examine the energy levels of the molecular orbitals.

The molecular orbital diagram of Li2 can be built by combining the atomic orbitals of two lithium (Li) atoms. Each lithium atom contributes one electron to the molecular orbitals. Since lithium has three electrons, two of them will occupy the lower-energy orbitals (bonding orbitals), and one will occupy the higher-energy orbital (anti-bonding orbital).

In the molecular orbital diagram of Li2, the lowest energy level is the σ bonding orbital. This bonding orbital is formed by the constructive overlap of the atomic orbitals of the two lithium atoms. The two electrons occupy this orbital, stabilizing the molecule.

Above the σ bonding orbital is the σ* anti-bonding orbital, which results from the destructive overlap of the atomic orbitals. The presence of an electron in this anti-bonding orbital destabilizes the molecule.

Considering the molecular orbital diagram of Li2, we can see that the bonding orbital is occupied by two electrons, while the anti-bonding orbital has one electron. This electron configuration indicates that the bond in Li2 is not completely stable because there is an unpaired electron in the anti-bonding orbital. The presence of an unpaired electron suggests that the bond in Li2 is relatively weak compared to a stable, fully occupied bond.

In summary, the bond in the molecular orbital energy level diagram of Li2 is not completely stable due to the presence of an unpaired electron in the anti-bonding orbital.