This type of bond occurs in groups in which hydrogen is bonded with atoms of high electronegativity, e.g. oxygen, nitrogen, fluorine. The then positively polarised hydrogen atom then exerts a strong attraction on neighbouring negative ions or negatively polarised atoms. Such hydrogen atoms are found in groups such as -OH, -NH2 and -COOH. The resulting bonding forces are much greater than the Van der Waals forces and the dispersion forces.