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Lead - Pb General Information Discovery Lead was known to ancient civilisations, and is mentioned in Exodus. Appearance Lead is a soft, weak, ductile metal with a pale grey sheen. Source Lead is obtained chiefly from the mineral galena by a roasting process. At least 40% of lead in the UK comes from secondary lead sources such as scrap batteries and pipes. Uses Lead is very resistant to corrosion - lead pipes from Roman times are still in use today - and is often used to store corrosive liquids. Great quantities of lead, both as the metal and the dioxide, are used in batteries. Lead is also used in cable covering, plumbing and ammunition. Tetraethyl lead is used as an anti-knock agent in petrol, and as an additive in paints. The use of lead in plumbing, petrol and paints has been reduced in the past few years because of environmental concern, as lead is a cumulative poison and is thought to affect brain development and function, especially in young children. Lead is an effective shield around X-ray equipment and nuclear reactors. Lead oxide is used in the production of fine crystal glass. Biological Role Lead has no known biological role. It is toxic in a cumulative way, teratogenic and carcinogenic. General Information Lead is stable to air and water, but will tarnish in moist air over long periods. It dissolves in nitric acid. Lead is a poor conductor of electricity. |
| Physical Information | |||
| Atomic Number | 82 | ||
| Relative Atomic Mass (12C=12.000) | 207.2 | ||
| Melting Point/K | 600 | ||
| Boiling Point/K | 2013 | ||
| Density/kg m-3 | 11350 (293K) | ||
| Ground State Electron Configuration | [Xe]4f145d106s26p2 | ||
| Electron Affinity(M-M-)/kJ mol-1 | -35.2 |
| Key Isotopes | ||||||
| nuclide | 204Pb | 205Pb | 206Pb | 207Pb | 208Pb | |
| atomic mass | 203.97 | 205.97 | 206.98 | 207.98 | ||
| natural abundance | 1.4% | 0% | 24.1% | 22.1% | 52.3% | |
| half-life | stable | 3x107 yrs | stable | stable | stable | |
| nuclide | 210Pb | 214Pb | ||||
| atomic mass | ||||||
| natural abundance | trace | trace | ||||
| half-life | 20.4 yrs | 10.6 hrs | ||||
| Other Information | ||
| Enthalpy of Fusion/kJ mol-1 | 5.12 | |
| Enthalpy of Vaporisation/kJ mol-1 | 177.8 | |
| Oxidation States | ||
| Pb+2, Pb+4 | ||
| Covalent Bonds /kJ mol-1 | ||
| Pb - H | 180 | |
| Pb -C | 130 | |
| Pb - O | 398 | |
| Pb - F | 314 | |
| Pb - Cl | 244 | |
| Pb - Pb | 100 | |
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 715.5 | |
| M+ - M2+ | 1450.4 | |
| M2+ - M3+ | 3081.5 | |
| M3+ - M4+ | 4083 | |
| M4+ - M5+ | 6640 | |
| M5+ - M6+ | 8100 | |
| M6+ - M7+ | 9900 | |
| M7+ - M8+ | 11800 | |
| M8+ - M9+ | 13700 | |
| M9+ - M10+ | 16700 | |
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