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Strontium - Sr General Information Discovery Strontium was isolated by Sir Humphry Davy in 1808 in London, but recognised as an element by A. Crawford in 1790. Appearance Strontium is a silvery-white, soft metal which rapidly forms the yellowish colour of the oxide when cut. Source Strontium is found mainly in the minerals celestite and strontianite. It can be prepared by electrolysis of the fused chloride with potassium chloride, or by reducing strontium oxide with aluminium. Uses Strontium is mainly used for producing glass for colour television sets. It is also used in producing ferrite magnets and refining zinc. One of the radioactive isotopes of strontium, 90Sr, is a product of nuclear fallout and presents a health problem. It has a half-life of 28 years. It is absorbed by bone tissue instead of calcium and can destroy bone marrow and cause cancer. However, it is also a useful isotope as it is one of the best high-energy beta-emitters known. Biological Role Strontium has no known biological role, and it is non-toxic. It replaces and mimics calcium. General Information Strontium will burn in air and reacts with water more vigorously than calcium. It is usually kept under paraffin to prevent oxidation. |
| Physical Information | |||
| Atomic Number | 38 | ||
| Relative Atomic Mass (12C=12.000) | 87.62 | ||
| Melting Point/K | 1042 | ||
| Boiling Point/K | 1657 | ||
| Density/kg m-3 | 2540 (293K) | ||
| Ground State Electron Configuration | [Kr]5s2 | ||
| Electron Affinity(M-M-)/kJ mol-1 | +146 |
| Key Isotopes | ||||||
| nuclide | 82Sr | 84Sr | 85Sr | 86Sr | 87Sr | |
| atomic mass | 83.91 | 84.91 | 85.91 | 86.91 | ||
| natural abundance | 0% | 0.56% | 0% | 9.86% | 7% | |
| half-life | 25 days | stable | 64 days | stable | stable | |
| nuclide | 88Sr | 89Sr | 90Sr | |||
| atomic mass | 87.91 | 88.91 | 89.91 | |||
| natural abundance | 82.58% | 0% | 0% | |||
| half-life | stable | 52.7 days | 28.1 yrs | |||
| Other Information | ||
| Enthalpy of Fusion/kJ mol-1 | 9.16 | |
| Enthalpy of Vaporisation/kJ mol-1 | 154.4 | |
| Oxidation States | ||
| Sr+2 | ||
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 549.5 | |
| M+ - M2+ | 1064.2 | |
| M2+ - M3+ | 4210 | |
| M3+ - M4+ | 5500 | |
| M4+ - M5+ | 6910 | |
| M5+ - M6+ | 8760 | |
| M6+ - M7+ | 10200 | |
| M7+ - M8+ | 11800 | |
| M8+ - M9+ | 15600 | |
| M9+ - M10+ | 17100 | |
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