Question

Covalent bonds can undergo fission in two different ways. The correct representation involving a heterolytic fission of $C{H}_3–Br$ is

• A. $\curvearrowright$ $\oplus$ $\ominus$
  $C{H}_3-Br\to C{H}_3+Br$
• B. $\curvearrowright$ $\ominus$ $\oplus$
  $C{H}_3-Br\to C{H}_3+Br$
• C. $\curvearrowleft$ $\oplus$ $\ominus$
  $C{H}_3-Br\to C{H}_3+Br$
• D. $\curvearrowleft \curvearrowright$ $\bullet$ $\bullet$
  $C{H}_3-Br\to C{H}_3+Br$

Answer 1

The correct option is A $\curvearrowright$ $\oplus$ $\ominus$

$C{H}_3-Br\to C{H}_3+Br$

Covalent bond undergoes fission in two ways:

Heterolytic fission

It involves unequal sharing of bonded electron pairs between bonded atoms. The more electronegative atom will pull the shared pair of bonded electrons, causing negative charge on it and positive charge on less electronegative atoms.

$\curvearrowright$ $+$
$C{H}_3-Br\to C{H}_3+B{r}^{-}$

Step 2: Homolytic cleavage

In homolytic cleavage, one of the electrons of the shared pair in a covalent bond goes with each of the bonded atoms. Thus, in homolytic cleavage, the movement of a single electron takes place instead of an electron pair. Occurs majorly in covalent bond between atoms with same electronegativity.

$\curvearrowleft \curvearrowright$ $\bullet$ $\bullet$
$X-X\to X+X$

Analysing the options :

$\left(A\right)$ Arrow shown is not correct. Movement of electrons is shown on less electronegative elements.

$\left(C\right)$ Negative charge is on less electronegative element and positive charge is on more negative element.

$\left(D\right)$ This is homolytic bond cleavage.

Hence, option $\left(B\right)$ is correct.