Question

The table shown below gives the bond dissociation energies (\[{{E}_{diss}}\]) for single covalent bonds of carbon atoms with elements A, B, C, and D. Which element has the smallest atoms?

Bond	\[{{E}_{diss}}\](kJ/mol)
C−A	240
C−B	328
C−C	276
C−D	485

A. A
B. B
C. C
D. D

Answer 1

Hint: The bond dissociation energy is defined as the quantity of energy that is needed to break one mole of gases into a couple of radicals.
Its SI unit is kilojoules per mole of bonds (kJ/mol). It implies how strong the bond is.

Complete step by step solution:A covalent bond can be broken down heterolytically where the shared pair of electrons move with one unit or another.
It can also occur homolytically, where one electron remains with each partner.
\[A-B\to {{A}^{\bullet}}+{{B}^{\bullet}}\]
Radicals formed as a result of homolytic cleavage and the energy needed to break the bond homolytically is called the bond dissociation energy.
The two bonded atoms become bigger, and the area occupied by bonding electrons becomes smaller. So, the energy required to break the bond is less.
So, the bond dissociation energy of a greater atom is less.
Here in the given question, the carbon atom is common in all the given covalent bonds.
The bond dissociation energy of C-D is the highest. So, the size of D is the smallest.

So, option D is correct.

Note: Bond dissociation energy is a state function and thus does not rely on the path by which it happens. It helps to evaluate the energetics of chemical processes.
If we add bond dissociation energies for bonds formed and bonds broken in a chemical reaction utilizing Hess's Law, we can calculate reaction enthalpies.