Due to the high electronegativity of flourinehydrogen bonds can be formed between HF molecules. - Hydrogen bonds require more energy to break that London Forces. - The other halogens are not as electronegative and so other hydrogen halides cannot form hydrogen bonds between molecules. Only London Forces are formed. - Therefore more energy is required to break the intermolecular forces in HF than the other hydrogen halides and so it has a higher boiling point.