Final answer:
The most covalent bonds are Cl-Cl, C-O, and N-O for each set, determined by the smaller differences in electronegativity between the bonded atoms, and valence bond theory which explains the extent of orbital overlap.
Step-by-step explanation:
The covalent bond that is the most covalent within each set provided can be determined by considering the difference in electronegativity between the atoms forming the bond. The lesser the difference in electronegativities, the more covalent (and less ionic) the bond is.
- Cl-Cl vs. Al-F: Cl-Cl is more covalent because both chlorine atoms have the same electronegativity, resulting in the equal sharing of electrons.
- N-O vs. C-O: C-O is more covalent given that the electronegativity difference between carbon and oxygen is less than that between nitrogen and oxygen.
- Ca-O vs. N-O: N-O is more covalent because the electronegativity difference between calcium and oxygen is greater than that between nitrogen and oxygen, making Ca-O more ionic.
Furthermore, covalent bonds can be predicted by valence bond theory, which involves the overlap of atomic orbitals. The strength of a covalent bond can often be determined by the extent of orbital overlap, with stronger overlap resulting in a stronger bond.