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Radium - Ra General Information Discovery Radium was discovered by Pierre and Marie Curie in 1898 in Paris, France, from pitchblende. There is about 1 gram of radium in 7 tonnes of pitchblende. It was isolated in 1911 by Marie Curie and Debierne, by the electrolysis of a solution of pure radium chloride. Appearance Pure radium is brilliant white when freshly prepared, but blackens on exposure to the air. The metal and its salts luminesce. Source Radium is present in all uranium ores, and could be extracted as a by-product of uranium refining. The usual source of pitchblende comes from Bohemia, but some radium-containing ores are found in Canada and the USA. Annual production of this element is less than 100 grams. Uses Radium was formerly used in the production of luminous paints, but this is now considered too hazardous. The element gives off small amounts of radium gas which has been used to treat cancer, but this use is now also considered too toxic - other radioactive sources are more powerful and safer to use. Biological Role Radium has no known biological role. It is toxic due to its radioactivity. General Information Radium reacts with both oxygen and water, and is somewhat more volatile than barium. It burns with a carmine red colour. Radium emits alpha, beta and gamma rays. The final product of its disintegration is lead. |
| Physical Information | |||
| Atomic Number | 88 | ||
| Relative Atomic Mass (12C=12.000) | 226.02 | ||
| Melting Point/K | 973 | ||
| Boiling Point/K | 1413 | ||
| Density/kg m-3 | 5000 (293K) | ||
| Ground State Electron Configuration | [Rn]7s2 |
| Key Isotopes | ||||||
| nuclide | 223Ra | 224Ra | 226Ra | 228Ra | ||
| atomic mass | 223.02 | 224.02 | 226.03 | 228.03 | ||
| natural abundance | some | some | some | some | ||
| half-life | 11.43 days | 3.64 days | 1602 yrs | 5.77 yrs |
| Other Information | ||
| Enthalpy of Fusion/kJ mol-1 | 7.15 | |
| Enthalpy of Vaporisation/kJ mol-1 | 136.7 | |
| Oxidation States | ||
| RaII | ||
| Covalent Bonds /kJ mol-1 | ||
| not applicable | ||
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 509.3 | |
| M+ - M2+ | 979 | |
| M2+ - M3+ | 3300 | |
| M3+ - M4+ | 4400 | |
| M4+ - M5+ | 5700 | |
| M5+ - M6+ | 7300 | |
| M6+ - M7+ | 8600 | |
| M7+ - M8+ | 9900 | |
| M8+ - M9+ | 13500 | |
| M9+ - M10+ | 15100 | |
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