#55 Cesium

Caesium (IUPAC spelling) or cesium (American spelling) is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28.5 C (83.3 F), which makes it one of only five elemental metals that are liquid at or near room temperature.

Atomic mass:132.90546 amu

Melting point:28.5 C (301.65 K, 83.3 F)

Boiling point:678.4 C (951.55005 K, 1253.12 F)

Density:293 K: 1.873 g/cm3