Electronegativity values of some elements are given. Using these values, find whether the following compounds are ionic or covalent.

(Electronegativity of Ca=1.0, O = 3.5, C = 2.5, S = 2.58, H = 2.2, F = 3.98)

Sulphur dioxide (SO₂) Water (H₂O)

Calcium fluoride (CaF₂) Carbon dioxide (CO₂)

Electronegativity difference between the constituent elements of a

compound decide the nature of compound. If the difference is 1.7 or more

than 1.7, then it generally shows ionic character and if its less than 1.7 it shows covalent character. Subtracting the respective electronegativity values of constituents gives difference.

1. Electronegativity difference of SO₂ is-

Electronegativity of O – Electronegativity of S

= 3.5 – 2.58 = 0.92

0.92 < 1.7 ; hence its covalent

2. Electronegativity difference of H₂O is-

Electronegativity of O – Electronegativity of H

= 3.5 – 2.2 = 1.3

1.3 < 1.7 ; hence its covalent

3. Electronegativity difference of CaF₂ is-

Electronegativity of F – Electronegativity of Ca

= 3.98 – 1.0 = 2.98

2.98 > 1.7 ; hence its ionic

4. Electronegativity difference of CO₂ is-

Electronegativity of O – Electronegativity of C

= 3.5 – 2.5 = 1.0

1 < 1.7 ; hence its covalent