Question

the bond energy for a c -h bond is about 413 kj/mol in ch4 but 380 kj/mol in chbr3. although these values are relatively close in magnitude, they are different. explain why they are different on the basis of electronegativity.

Answer 1

A chemical link must be essentially of electronic description. The behavior and distribution of electrons around the nucleus is what gives the fundamental character of an atom, and the same must be true for molecules.

The description of the links being its electronic distribution.

Electronegativity is the measure of the tendency of an atom in a molecule to attract electrons to itself, and estimates it from the bond energies or dissociation energies of various substances.

The more united the atoms are in a molecule, the greater the value of the bond energy. In methane you have four equivalent C-H bonds, but in the CHBr3 the electronegativity is greater which decreases its bond energy.