Bond polarity (3.1.3.6)

What is electronegativity?

Electronegativity - the measure of the ability of an atom’s nucleus to attract a bonding pair of electrons in a covalent bond

The greater the electronegativity of an atom, the more it attracts electrons towards it

How do electronegativities of the atoms in a bond affect the type of bond?

Type of bond	Explanation
Pure covalent	Atoms have similar electronegativities so the bonding pair of electrons is halfway between them
Polar	Atoms have a difference in electronegativities so the bonding pair is attracted to the more electronegative atom (δ-)
Ionic	Considerable difference in electronegativity so ions form

How does electronegativity change as you move across a period?

It increases across a period as the nuclear charge increases and the shielding stays the same so the atomic radius gets smaller so there is a stronger attraction between the nucleus and bonding pair.

How does electronegativity change as you go down a group?

It decreases down a group as the shielding increases so the atomic radius increases so there is a weaker attraction between the nucleus and bonding pair.