Radium
Radium General
| Name:Radium | Symbol:Ra |
| Type:Alkali Earth Metal | Atomic weight:226.0254 |
| Density @ 293 K:5.5 g/cm3 | Atomic volume:45.20 cm3/mol |
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Discovered:
Radium was discovered in 1898 by Marie S. Curie and her husband Pierre in pitchblende (mainly uranium dioxide UO2). If pitchblende contains 50 percent uranium oxides, about eight tons of it is needed to extract 1 gram of radium. Already that year the Curies had discovered polonium, a radioactive element whose properties they said were similar to bismuth's. Now, in radium - in the form of radium bromide - they had discovered a further radioactive element whose chemistry was very similar to that of group II metal barium. Metallic radium was first isolated in 1910 by Marie S. Curie and Andre Debierne by the electrolysis of a solution of pure radium chloride. The element's name comes from the Latin word 'radius', meaning ray, after the rays emitted by this radioactive element. In the discovery of radioactivity, chemists realized that one of alchemy's dreams - the transmutation of elements - was possible. |
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Radium States
| State (s, l, g):solid | |
| Melting point:973 K (700 °C) | Boiling point:1773 K (1500 °C) |
Radium Energies
| Specific heat capacity:0.12 J g-1 K-1 | Heat of atomization:159 kJ mol-1 |
| Heat of fusion:8.5 kJ mol-1 | Heat of vaporization :113 kJ mol-1 |
| 1st ionization energy: 509.4 kJ mol-1 | 2nd ionization energy: 979.1 kJ mol-1 |
| 3rd ionization energy: kJ mol-1 | Electron affinity: kJ mol-1 |
Radium Oxidation & Electrons
| Shells:2,8,18,32,18,8,2 | Electron configuration:[Rn] 7s2 |
| Minimum oxidation number:0 | Maximum oxidation number:2 |
| Min. common oxidation no.:0 | Max. common oxidation no.:2 |
| Electronegativity (Pauling Scale):0.9 | Polarizability volume:38.3 Å3 |
Radium Appearance & Characteristics
| Structure:bcc: body-centered cubic | Color: silvery white |
| Hardness:mohs | |
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Harmful effects:
Radium is highly radioactive and hence carcinogenic. Microscopic quantities of radium in the environment can lead to some accumulation of radium in bone tissue. Radium, like calcium, is a group II element and our bodies treat it in a similar way. |
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Characteristics:
Radium is a silvery-white metal. It is highly radioactive and its decay product, radon gas, is also radioactive. One result of radium's intense radioactivity is that the metal and its compounds glow in the dark. When it is exposed to air, it reacts with nitrogen to quickly form a black coating of radium nitride. Uses: Radium was used in the production of luminous paints, but this is now considered too dangerous. Radium chloride was used medicinally to produce radon gas for cancer treatment. Safer treatments are now available. |
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Radium Reactions
| Reaction with air:vigorous, ⇒ RaO2, Ra3N2 | Reaction with 6 M HCl: |
| Reaction with 15 M HNO3: | Reaction with 6 M NaOH: |
Radium Compounds
| Oxide(s):RaO | Chloride(s):RaCl2 |
| Hydride(s): |
Radium Radius
| Atomic radius:215 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion):162 pm | Ionic radius (3+ ion): pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Radium Conductivity
| Thermal conductivity:18.6 W m-1 K-1 | Electrical conductivity:1 x 106 S m-1 |
Radium Abundance & Isotopes
| Abundance earth's crust:1 part per trillion by weight, 0.1 parts per trillion by moles | |
| Abundance solar system:parts per billion by weight, part per billion by moles | |
| Cost, pure:$ per 100g | |
| Cost, bulk:$ per 100g | |
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Source:
Radium is present in tiny amounts in all uranium ores - it arises from uranium decay. Radium is present at very low concentrations in sea water. Most radium, 226Ra, arises from the decay of the plentiful 238U, hence radium is obtained in residues taken from uranium production. |
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Isotopes:
Radium has 33 isotopes whose half-lives are known, with mass numbers 202 to 234. None is stable. 226Ra has the longest half-life of 1602 years. |
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Radium Other
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Other:
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