which bond from each set has the greatest bond energy and why?
A. N-O or N-F
B. B-F or B-Cl
C. B-C or O-F
D. C-O or C=O
E. P-Br or P-Cl

Question

which bond from each set has the greatest bond energy and why?
A. N-O or N-F
B. B-F or B-Cl
C. B-C or O-F
D. C-O or C=O
E. P-Br or P-Cl

anonymous · Answer

A.  N-F, because the F atom is smaller than the O and can get in closer to the N atom, improving the overlap of AOs that form the bonding MO. 

B. B-F, again because the F atom is smaller than the Cl.

C. B-C, and I'm not entirely sure why -- it may be that there is some coordinate covalent pi bonding going on, with overlap between the filled p orbitals on the C and the empty p orbitals on the B.

D. C=O, because it's a double bond.

E. P-Cl, because Cl is smaller than Br.