Topic 4 - Chemical bonding and structure - 4.2 Covalent bonding

Nature of science:

Looking for trends and discrepancies. Compounds containing non-metals have different properties than compounds that contain non-metals and metals. 2.5

Use theories to explain natural phenomena. Lewis introduced a class of compounds which share electrons. Pauling used the idea of electronegativity to explain unequal sharing of electrons. 2.2


A covalent bond is formed by the electrostatic attraction between a shared pair of electrons and the positively charged nuclei.

Single, double and triple covalent bonds involve one, two and three shared pairs of electrons respectively.

Bond length decreases and bond strength increases as the number of shared electrons increases.

Bond polarity results from the difference in electronegativities of the bonded atoms.

Applications and skills

Deduction of the polar nature of a covalent bond from electronegativity values.


Bond polarity can be shown either with partial charges, dipoles or vectors.

Electronegativity values are given in the data booklet in section 8.