Ra
Radium
RADIUM
ALKALINE EARTH METAL
| Atomic number: | 88 |
| Group numbers: | 2 |
| Period: | 7 |
| Electronic configuration: | [Rn] 7s2 |
| Formal oxidation number: | +2 |
| Electronegativities: | 0.9 |
| Atomic radius / pm: | 235 |
| Relative atomic mass: | - |
Radium was discovered by Marie Sklodowska Curie and Perre Curie (FR) in 1898. The origin of the name comes from the Latin word radius meaning ray. It is a silvery-white radioactive metal that reacts with oxygen and water. It is highly radiotoxic and carcinogen by inhalation, ingestion, or exposure. Radium is found in uranium ores at 1 part per 3 million parts uranium. Used in treating cancer because of the gamma rays it gives off.
| Density / g dm-3: | 5000 | (293 K) |
| Molar volume / cm3mol-1: | 45.20 | (est., 293 K) |
| Electrical resistivity / µΩcm: | 100 | (20 °C) |
| Thermal conductivity / W m-1K-1: | 18.6 |
| Melting point / °C: | 700 |
| Boiling point / °C: | 1140 |
| Heat of fusion / kJ mol-1: | 7.15 |
| Heat of vaporization / kJ mol-1: | 136.7 |
| Heat of atomization / kJ mol-1: | 159 |
| First ionization energy / kJ mol-1: | 509.29 |
| Second ionization energy / kJ mol-1: | 979.06 |
| Third ionization energy / kJ mol-1: | - |
| in the atmosphere / ppm: | - |
| in the Earth's crust / ppm: | - |
| in the oceans / ppm: | 3E-11 |
| Crystal structure: | body-centered cubic |
| Unit-cell dimensions / pm: | a=515 |
| Space group: | Im3m |
| Isotope | Relative atomic mass | Mass percent (%) |
|---|---|---|
| 226Ra | 226.025 41(2) | * |
| 228Ra | 228.031 07(2) | * |
| Balanced half-reaction | Eo / V | |
|---|---|---|
| Ra2+ + 2e- → Ra(s) | - 2.92 |
| 87 Francium | ← | 88 Radium | → | 89 Actinium |
Citing this page:
Generalic, Eni. "Radium." EniG. Periodic Table of the Elements. KTF-Split, 13 Feb. 2025. Web. {Date of access}. <https://www.periodni.com/ra.html>.
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