Question

The correct sequence of increasing covalent character is represented by:-
(a)$LiCl < NaCl < BeC{{l}_{2}}$
(b)$BeC{{l}_{2}} < LiCl < NaCl$
(c)$NaCl < LiCl < BeC{{l}_{2}}$
(d)$BeC{{l}_{2}} < NaCl < LiCl$

Answer 1

As we know that in ideal situations a bond is said to be hundred percent ionic or covalent in nature whereas in reality, no bond is neither completely ionic or covalent. So in the ionic compounds, the ionic bonds between the atoms do have covalent character as well. All the compounds given in the option are ionic compounds and we have to tell the increasing covalent character in them.

Complete answer:
Let us understand the concept of covalent character in ionic bonds followed by telling the sequence of increasing order of covalent character as follows:-
-Ionic bond is formed when an atom donates its electrons to another atom which accepts that electron. In ideal situations a bond is said to be hundred percent ionic or covalent in nature whereas in reality, no bond is neither completely ionic or covalent. Therefore in the ionic compounds, the ionic bonds between the atoms do have covalent character as well.
-The partial existence of covalent characters in an ionic bond is discussed by Fajan’s Rule as follows:
The difference in the size of the ions determines the percentage of covalent character that exists in the ionic bond which means if the size of the cation is very small and that of the anion is very large then the ionic bond will show more covalent characters.
Also the covalent character between two atoms depends on their electronegativity difference. If the electronegativity difference is high, the covalent character is less but if the electronegativity difference is low, the covalent character is more.
-We know that electronegativity increases from bottom to top and left to right in the periodic table.
-All the given compounds have one atom that has chlorine, so we just need to check the electronegativity of the other atoms bonded to chlorine so as to give the order of covalent character on basis of it.
-The order of electronegativity is: $Na < Li < Be$ .
Therefore the order of increased covalent character is: (c) $NaCl < LiCl < BeC{{l}_{2}}$ .

Note:
-Remember that if there is greater charge present on the cation then more will be the covalent characters of the ionic bond as cation polarize the anion and try to pull the electronic charge towards itself.
-Also understand and understand all types of bonding that exist between the atoms.