Liquid the distances between the molecules become smaller. When the liquid reaches its freezing point the molecules will usually lock into a very specific order, called crystallizing, and the bonds between them become more rigid, changing the liquid into its solid state (unless supercooling occurs). Only two elements are liquid at standard conditions for temperature and pressure: mercury and bromine. Four more elements have melting points slightly above room temperature: francium, caesium, gallium and rubidium. Metal alloys that are liquid at room temperature include NaK, a sodium-potassium metal alloy, galinstan, a fusible alloy liquid, and some amalgams (alloys involving mercury). Pure
Room temperature of the English Language" identifies room temperature as around , while the "Oxford English Dictionary" states that it is "conventionally taken as about ". Owing to variations in humidity and likely clothing, recommendations for summer and winter may vary; a suggested typical range for summer is , with that for winter being , although by other considerations the maximum should be below – and to avoid sick building syndrome, below . Some studies have suggested that thermal comfort preferences of men and women may differ significantly, with women on average preferring higher ambient temperatures. The World Health Organization's standard for