Q9.56P - Chemistry: Molecular Nature Of Matter And Change

Question

How is the partial ionic character of a bond in a diatomic molecule related to $\mathbf{\text{ΔEN}}$  for the bonded atoms? Why?

Step-by-Step Solution

Answer

In a diatomic molecule, the partial charge character of a bond depends upon the difference in electronegativity of the atom.

The more electronegativity difference present between two atoms in an ionic molecule, the more polar the bond.

Step 1: Definition of electronegativity.

Electronegativity is defined as the property of an atom/molecule to attract the electron of the other atom/molecule. Every atom has an electronegativity property which depends on the size of the atom and also the electron cloud.

Electronegativity is inversely proportional to the size of an atom and directly proportional to the polarity of the bond.

 

Step 2: Explanation

The electronegativity of the atom depends upon the size, i.e., small size atoms are more electronegative and the nature of the atom. Higher the electronegativity closer the electron cloud to the nucleus. The polarity in the bonding of the molecule depends upon the difference in the electronegativity of the atom involved.

In a partial ionic bond, there is the formation of induced cations and anions. The more negative the anion, the more polar is the bond. If the anion is more electronegative then the difference in the electronegativity increase. As the difference in electronegativity increases in the bond, the bond becomes more polar.

For example, the electronegativity difference between Sodium and Chlorine is greater than that of the difference between hydrogen and chlorine.

               

                       Therefore, NaCl is ionic and HCl is a polar covalent bond.