Element 37
Rubidium (Rb)
Rubidium (Rb) is element 37 of the periodic table, a alkali metal in period 5, group 1 (s-block) with an atomic mass of 85.468 and is a solid at standard conditions.
At a glance
- Atomic number
- 37
- Symbol
- Rb
- Atomic mass
- 85.468 u
- Category
- Alkali metals
- Period
- 5
- Group
- 1
- Block
- s-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s1
- Shorthand configuration
- [Kr] 5s1
- Electrons per shell
- 2, 8, 18, 8, 1
- Oxidation states
- -1, +1
Physical properties
- Melting point
- 312.46 K
- Boiling point
- 961 K
- Density
- 1.532 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 0.82
- Atomic radius
- 265 pm
- Covalent radius
- 220 pm
- Van der Waals radius
- 303 pm
- First ionization energy
- 403 kJ/mol
- Electron affinity
- 47 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Rb-85 | 84.91179 | 72.17% | Stable |
Common uses
- Atomic clocks
- Electronics
- Fireworks
- Photocells
Discovery
- Year
- 1861
- Discovered by
- Robert Bunsen, Gustav Kirchhoff
- Country
- Germany