Rubidium (Rb)
Rubidium (Rb) is element 37 of the periodic table, an alkali metal in period 5 and group 1. Its standard atomic weight is 85.4678, so one mole of rubidium atoms has a mass of 85.4678 g. At room temperature it is a solid; it melts at 39.31 °C and boils at 687.85 °C.
| Atomic number | 37 |
|---|---|
| Symbol | Rb |
| Standard atomic weight | 85.4678 |
| Molar mass | 85.4678 g/mol |
| Category | Alkali metal |
| Group | 1 |
| Period | 5 |
| Block | s-block |
| Electron configuration | [Kr] 5s1 |
| Oxidation states | +1 |
| Electronegativity (Pauling) | 0.82 |
| Atomic radius (van der Waals) | 303 pm |
| First ionisation energy | 4.177 eV (403 kJ/mol) |
| Electron affinity | 0.468 eV |
| State at room temperature | Solid |
| Melting point | 312.46 K (39.31 °C) |
| Boiling point | 961 K (687.85 °C) |
| Density | 1.53 g/cm³ |
| Discovered | 1861 |
Group 1
Calculate with Rubidium
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.