Cesium is a chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of 28.44 °C (83.19 °F), which makes it one of only five elemental metals that are liquid at or near room temperature.
This low melting point is due to the relatively large size of the cesium atoms and the weak metallic bonding between them. This weak bonding results in a low energy barrier between the solid and liquid states, making it easier for cesium to transition from a solid to a liquid.
The low melting point of cesium has several implications for its use and handling. For example, cesium must be stored and transported in a cool, dry environment to prevent it from melting. This requirement is particularly important when dealing with large quantities of cesium, as the metal can pose a fire hazard if it meets other flammable materials.
In addition to its low melting point, cesium is known for its high reactivity and its ability to ignite spontaneously in the air. This high reactivity makes cesium dangerous to handle and limits its use in many applications.
Despite these challenges, cesium has important industrial uses, including as a component of atomic clocks, as a catalyst in chemical reactions, and as a lubricant in high-temperature environments.