Element 88
Radium (Ra)
Radium (Ra) is element 88 of the periodic table, a alkaline earth metal in period 7, group 2 (s-block) with an atomic mass of 226 and is a solid at standard conditions.
At a glance
- Atomic number
- 88
- Symbol
- Ra
- Atomic mass
- 226 u
- Category
- Alkaline earth metals
- Period
- 7
- Group
- 2
- Block
- s-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s2
- Shorthand configuration
- [Rn] 7s2
- Electrons per shell
- 2, 8, 18, 32, 18, 8, 2
- Oxidation states
- +2
Physical properties
- Melting point
- 973 K
- Boiling point
- 2010 K
- Density
- 5.5 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 0.9
- Atomic radius
- 283 pm
- Covalent radius
- 221 pm
- Van der Waals radius
- 283 pm
- First ionization energy
- 509 kJ/mol
- Electron affinity
- 10 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Ra-226 | 226.02541 | — | Half-life 1600 years |
Common uses
- Cancer treatment
- Luminous paints (historical)
- Research
Discovery
- Year
- 1898
- Discovered by
- Marie Curie, Pierre Curie
- Country
- France