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 comfortable warmth is for normal, healthy adults who are appropriately dressed. For those with respiratory problems or allergies, they recommend no less than , and for the sick, disabled, very old or very young, a minimum of . Temperature ranges are defined as "room temperature" for certain products and processes in industry, science, and consumer goods. For instance, for the shipping and storage of pharmaceuticals, the United States Pharmacopeia-National Formulary (USP-NF) defines "controlled room temperature" as between , with excursions between allowed, provided the mean kinetic temperature does not exceed . The European Pharmacopoeia defines it as being simply ,