Q29P - Chemistry: Molecular Nature Of Matter And Change

Question

Which member of each pair has more covalent character in

its bonds: (a) LiCl or KCl; (b) AlCl₃ or PCl₃; (c) NCl₃ or AsCl₃?

Step-by-Step Solution

Answer

(a) LiCl has a more covalent character.

(b) PCI₃ has more covalent character.

(c) NCI₃ has more covalent character.

Step 1: Covalent character

Covalent character is the measurement of bond polarization. Covalent character is mainly shown by the compound having the least electronegativity difference. In the periodic trend, the covalent character increases down the group and it also increases from left to right in the period. 

Generally, the higher the positive oxidation state of the central metal atom tends to higher the polarizing power which results in the more covalent character of the bond formed between the atom and its central metal atom.

Step 2: Identify the given compound having a more covalent character

(a) LiCl has more covalent character than KCl, because the electronegativity difference between Li and Cl is more as compared to the electronegativity difference between K and Cl atom, and due to the smaller size of Li⁺  as compared to K⁺ ion, polarization occurs more in LiCl, therefore, it becomes more covalent than KCl.

 

(b) PCI₃ has more covalent character than AICI₃, because covalent character increases as we move from left to right along period in the periodic table, therefore Aluminum with atomic number 13 has less covalent character as compared to Phosphorous with atomic number 15.

 

(c) NCI₃ has more covalent character than AsCI₃, because in the periodic trend covalent character increases down the group.