Electronegativity

• Electronegativity refers to the ability of an atom to draw an electron pair towards itself in a covalent bond

For example:

• Oxygen (O) is strong – it pulls electrons closer.

• Hydrogen (H) is weaker – it doesn’t pull as much.

When oxygen and hydrogen form water (H₂O), oxygen pulls the electrons closer to itself. Since electrons are negatively charged, when oxygen pulls them closer, it becomes slightly negative (δ⁻). Meanwhile, hydrogen loses some of that electron density, making it slightly positive (δ⁺).

If electrons are shared equally, e.g diatomic molecules, the molecule is nonpolar—no charge difference.

• The dipole moment is a measure of how polar a bond is

• The direction of the dipole moment is shown by the following sign in which the arrow points to the partially negatively charged end of the dipole

The sign shows the direction of the dipole moment and the arrow points to the delta negative end of the dipole