Radium
Radium (镭, symbol Ra) is chemical element number 88, an Alkaline Earth in period 7, group 2 of the periodic table, with a standard atomic weight of about 226. Luminescent radioactive alkaline earth metal. Once used in glow-in-the-dark paints.
Properties
| Atomic number | 88 |
|---|---|
| Symbol | Ra |
| Atomic mass | 226 u |
| Category | Alkaline Earth |
| Period | 7 |
| Group | 2 |
| Electron configuration | [Rn] 7s² |
| Electronegativity | 0.9 |
| Covalent radius | 221 pm |
| Density | 5.5 g/cm³ |
| Melting point | 973 K |
| Boiling point | 2010 K |
| Discovery | Marie & Pierre Curie, 1898 |
Overview
Luminescent radioactive alkaline earth metal. Once used in glow-in-the-dark paints. Radium (symbol Ra) is chemical element number 88, sitting in period 7, group 2 of the periodic table and classed as an Alkaline Earth. As an alkaline-earth metal it is a little less reactive than the alkali metals and occurs in nature mainly within mineral compounds.
With 2 electrons in its outermost shell, Radium bonds accordingly; full configuration [Rn] 7s², electronegativity 0.9. At room temperature it is normally a solid; it melts near 973 K (699.9 °C), boils near 2010 K (1736.9 °C), has a density around 5.5 g/cm³.
Common applications range across Medical / Pharma and Research. It is regarded as a high-hazard element, so handle it with appropriate care. It was first described by Marie & Pierre Curie in 1898. Use the comparison tool to line it up against other elements.
Electron shells
Electrons per shell: 2 · 8 · 18 · 32 · 18 · 8 · 2
Main uses
- Medical / Pharma
- Research
Hazard
Compounds containing Radium
No compounds in this knowledge base contain Radium yet.
Data sources
Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.