Cesium (Cs)
Cesium (Cs)
Cesium, an alkali metal, was discovered spectroscopically in 1860. It occurs in lepidolite, pollucte, and other sources.
Cesium is silvery-white, soft, ductile, and the most alkaline and most electropositive element. Cesium is one of just three metals that are liquid at room temperature. It reacts explosively with cold water and with ice when the temperature is above -116 °C.
The metal's spectrum contains two bright blue lines and several others in red, yellow, and green wavelengths.
Cesium is used in electron tubes and photoelectric cells, as a hydrogenation catalyst for specific organic compounds, and in atomic clocks.