Caesium/Cesium is a chemical element with symbol Cs and it is one of the most reactive metals on earth. Cesium is a soft, silvery-gold alkali metal and has a very low melting point – 28.5 °C (83.3 °F). This makes Cs one of only five elemental metals that are liquid at or near room temperature. Cesium reacts explosively with water at −116 °C (−177 °F). It is one quite unusual metal, it is considered as more precious than gold. Watch the video below – experiments with Cesium!