Final answer:
The key difference between heterodiatomic and homodiatomic molecular bonding is that homodiatomic molecules are composed of atoms of the same element resulting in nonpolar bonds, while heterodiatomic molecules consist of two different atoms and can form polar bonds due to differences in electronegativity.
Step-by-step explanation:
The main difference between heterodiatomic and homodiatomic molecular bonding lies in the types of atoms involved in forming the molecule. In a homodiatomic molecule, two atoms of the same element come together to form a bond, such as in hydrogen (H₂) or oxygen (O₂).
The molecular orbitals formed in this union are symmetric, and since the atoms have the same electronegativity, there is no dipole moment resulting in nonpolar molecules. In contrast, molecules comprise two different atoms, such as in carbon monoxide (CO) or hydrogen fluoride (HF).
These molecules exhibit a 'skewed' molecular orbital energy-level diagram due to the difference in electronegativity between the atoms. The bonding molecular orbitals have energies more similar to those of the more electronegative atom, leading to an uneven distribution of electron density and a polar covalent bond.
This results in a dipole moment where the electron density is closer to the more electronegative atom. Overall, the electronegativity difference and the resulting polarity of the bond are what distinguish heterodiatomic from homodiatomic bonding.