Question

Among $LiCl,BeC{l_2},BC{l_3}{\text{ and }}CC{l_4}$ the covalent bond character follows the order:
A.$LiCl > BeC{l_2} > BC{l_3} > CC{l_4}$
B.$LiCl < BeC{l_2} < BC{l_3} < CC{l_4}$
C.$LiCl > BeC{l_2} > CC{l_3} > BC{l_3}$
D.$LiCl < BeC{l_2} < CC{l_3} < BC{l_3}$

Answer 1

A covalent bond is defined as that bond that involves the sharing of electron pairs between atoms. A covalent bond is also known as a molecular bond and the sharing electron pairs are known as shared pairs of an electron.

Complete step by step answer:
As $Li,Be,B{\text{ and C}}$ all belong to the second period and on moving left to right non-metallic character increases as a result covalent character is also increasing. Also, we know that metals form an ionic bond, and nonmetal form a covalent bond. Hence the order of covalent character will be:
$LiCl < BeC{l_2} < BC{l_3} < CC{l_4}$.

Hence the correct answer will be B.

Additional information:
Atomic orbital except s orbitals have directional properties leading to different types of the covalent bond. The type of covalent bonds are:
Sigma (σ) bond: These bonds are formed by overlapping along the internuclear axis. These are the strongest bonds. Sigma bonds are usually single bonds.
Pi (π) bond: These bonds are formed by the sideways overlapping of the orbitals or we can say there is lateral overlapping perpendicular to the axis. These bonds are weaker as compared to the sigma bond. If there is a double bond between two atoms then there is one sigma and one pi bond whereas in the case of a triple bond there are two pi bonds and one sigma bond.

Note:
The covalent and ionic character of the chemical bond can be predicted by Fajan’s rule. According to this rule, covalent character and ionic character depends upon the size of cations and anions, and also the charge present on cations and anions. For a covalent character to exist in the case of cation, the charge should be larger and size should be smaller, wherein in the case of anion the size of anion should be large.