Question

Why are bonding molecular orbitals lower in energy than the parent atomic orbitals?

a) Electrons are more stable in molecular orbitals
b) Atomic orbitals have higher repulsion
c) Molecular orbitals have higher electron density
d) Atomic orbitals have lower overlap

Answer 1

Bonding molecular orbitals are lower in energy than parent atomic orbitals due to the stabilization that results from increased electron density between nuclei when orbitals overlap, leading to a more stable, lower-energy state.

Step-by-step explanation:

The question pertains to molecular orbital theory and why bonding molecular orbitals are lower in energy than the parent atomic orbitals. Bonding molecular orbitals are lower in energy because they allow for the stabilization of the electron density in close proximity to more than one nucleus. This stabilization occurs because the electrons in bonding orbitals are shared between the nuclei, which results in a lower energy state for the system.

Also, when two atomic orbitals overlap to create a bonding molecular orbital, the resulting orbital has increased electron density between the nuclei leading to an attraction between the positively charged nuclei and the negatively charged electrons, which further stabilizes the molecule.

The difference in energy between the atomic orbitals and the resulting molecular orbitals increases with the extent of the overlap between the atomic orbitals. Hence, greater overlap in the formation of bonding molecular orbitals leads to a greater energy decrease, or stabilization, of a molecule, compared to the separated parent atomic orbitals.