Caesium (Cs)
Caesium (Cs) is element 55 of the periodic table, an alkali metal in period 6 and group 1. Its standard atomic weight is 132.90545196, so one mole of caesium atoms has a mass of 132.90545196 g. At room temperature it is a solid; it melts at 28.44 °C and boils at 670.85 °C.
| Atomic number | 55 |
|---|---|
| Symbol | Cs |
| Standard atomic weight | 132.90545196 |
| Molar mass | 132.90545196 g/mol |
| Category | Alkali metal |
| Group | 1 |
| Period | 6 |
| Block | s-block |
| Electron configuration | [Xe] 6s1 |
| Oxidation states | +1 |
| Electronegativity (Pauling) | 0.79 |
| Atomic radius (van der Waals) | 343 pm |
| First ionisation energy | 3.894 eV (375.7 kJ/mol) |
| Electron affinity | 0.472 eV |
| State at room temperature | Solid |
| Melting point | 301.59 K (28.44 °C) |
| Boiling point | 944 K (670.85 °C) |
| Density | 1.93 g/cm³ |
| Discovered | 1860 |
Group 1
Calculate with Caesium
Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.