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Francium - Fr General Information Discovery Francium was discovered by Marguerite Perey in 1939 at the Curie Institute, Paris. Appearance Francium has never actually been seen, as it is a short-lived product of the decay of actinium. It is a highly radioactive metal. Source Francium occurs as a result of the alpha disintegration of actinium, which is obtained from the neutron bombardment of radium. It can also be made artificially by bombarding thorium with protons. Uses Francium has no uses. Biological Role Francium has no known biological role. It is toxic due to its radioactivity. General Information Francium occurs naturally in uranium minerals but to an extremely small extent - there is probably less than 10g of francium at any one time in the crust of the Earth. It is the most unstable of the first 101 elements of the Periodic Table. All its isotopes are highly unstable, so knowledge of its chemical properties comes from radiochemical techniques, and it most closely resembles caesium. |
| Physical Information | |||
| Atomic Number | 87 | ||
| Relative Atomic Mass (12C=12.000) | 223 (radioactive) | ||
| Melting Point/K | 300 | ||
| Boiling Point/K | 950 | ||
| Ground State Electron Configuration | [Rn]7s1 | ||
| Electron Affinity(M-M-)/kJ mol-1 | -44 |
| Key Isotopes | ||||||
| nuclide | 212Fr | 223Fr | ||||
| atomic mass | 223.02 | |||||
| natural abundance | 0% | some | ||||
| half-life | 19 mins | 22 mins |
| Other Information | ||
| Oxidation States | ||
| Fr+1 | ||
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 400 | |
| M+ - M2+ | 2100 | |
| M2+ - M3+ | 3100 | |
| M3+ - M4+ | 4100 | |
| M4+ - M5+ | 5700 | |
| M5+ - M6+ | 6900 | |
| M6+ - M7+ | 8100 | |
| M7+ - M8+ | 12300 | |
| M8+ - M9+ | 12800 | |
| M9+ - M10+ | 29300 | |
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