Lead

Lead 207.2(1) 2 4   Pb 82 [Xe] 6s24f145d106p2 [ ? ] Post-Transition Metal: Properties: Melting Point: 327.46 C Boiling Point: 1749 C Atomic Radius: 175.0 pm Heat of fusion: 4.77  kJ·mol−1 Heat of vaporization: 179.5  kJ·mol−1 Heat capacity (25 °C): 26.650  J·mol−1·K−1 Compounds: galena, anglesite, cerussite, minim Uses: solder, paints, radiation shielding Hazard: toxic

Lead, is a chemical element. It is a heavy metal, and is abundant in nature.
Lead has the symbol Pb (from the latin Plumbum) while its atomic number is 82. It is a bluish gray metal with strong metallic lustre when newly cut, but which tarnishes on exposure to humidity. Lead is very malleable, may be drawn to wire, and melts at low heat.

History

Long known, mentioned in Exodus. The alchemists believed lead to be the oldest metal and associated with the planet Saturn. Native lead occurs in nature, but is rare.

Sources

Lead is obtained chiefly from galena (PbS) by a roasting process. Anglesite, cerussite, and minim are other common lead minerals.

Properties

Lead is a bluish-white metal of bright luster. It is very soft, highly malleable, ductile, and a poor conductor of electricity. It is very resistant to corrosion; lead pipes bearing the insignia of Roman emperors, used as drains from the baths, are still in service. It is used in containers for corrosive liquids (such as sulfuric acid) and may be toughened by the addition of a small percentage of antimony or other metals.

Forms

Natural lead is a mixture of four stable isotopes: 204Pb (1.48%), 206Pb (23.6%), 207Pb (22.6%), and 208Pb (52.3%). Lead isotopes are the end products of each of the three series of naturally occurring radioactive elements: 206Pb for the uranium series, 207Pb for the actinium series, and 208Pb for the thorium series. Twenty seven other isotopes of lead, all of which are radioactive, are recognized.

Its alloys include solder, type metal, and various antifriction metals. Great quantities of lead, both as the metal and as the dioxide, are used in storage batteries. Much metal also goes into cable covering, plumbing, ammunition, and in the manufacture of lead tetraethyl.

Uses

The metal is very effective as a sound absorber, is used as a radiation shield around X-ray equipment and nuclear reactors, and is used to absorb vibration. White lead, the basic carbonate, sublimed white lead, chrome yellow, and other lead compounds are used extensively in paints, although in recent years the use of lead in paints has been drastically curtailed to eliminate or reduce health hazards.

Lead oxide is used in producing fine "crystal glass" and "flint glass" of a high index of refraction for achromatic lenses. The nitrate and the acetate are soluble salts. Lead salts such as lead arsenate have been used as insecticides, but their use in recent years has been practically eliminated in favor of less harmful organic compounds.

Handling

Care must be used in handling lead as it is a cumulative poison. Environmental concerns with lead poisoning has resulted in a national program to eliminate the lead in gasoline.

This article was originally sourced from http://periodic.lanl.gov/elements/82.html on 3/22/08