The Element Lead
[Click for Isotope Data]
Atomic Number: 82
Atomic Weight: 207.2
Melting Point: 600.61 K (327.46°C or 621.43°F)
Boiling Point: 2022 K (1749°C or 3180°F)
Density: 11.342 grams per cubic centimeter
Phase at Room Temperature: Solid
Element Classification: Metal
Period Number: 6 Group Number: 14 Group Name: none
What's in a name? From the Anglo-Saxon word lead. Lead's chemical symbol comes from the Latin word for waterworks, plumbum.
Say what? Lead is pronounced as LED.
History and Uses:
Lead has been known since ancient times. It is sometimes found free in nature, but is usually obtained from the ores galena (PbS), anglesite (PbSO4), cerussite (PbCO3) and minum (Pb3O4). Although lead makes up only about 0.0013% of the earth's crust, it is not considered to be a rare element since it is easily mined and refined. Most lead is obtained by roasting galena in hot air, although nearly one third of the lead used in the United States is obtained through recycling efforts.
Lead is a soft, malleable and corrosion resistant material. The ancient Romans used lead to make water pipes, some of which are still in use today. Unfortunately for the ancient Romans, lead is a cumulative poison and the decline of the Roman empire has been blamed, in part, on lead in the water supply. Lead is used to line tanks that store corrosive liquids, such as sulfuric acid (H2SO4). Lead's high density makes it useful as a shield against X-ray and gamma-ray radiation and is used in X-ray machines and nuclear reactors. Lead is also used as a covering on some wires and cables to protect them from corrosion, as a material to absorb vibrations and sounds and in the manufacture of ammunition. Most of the lead used today is used in the production on lead-acid storage batteries, such as the batteries found in automobiles.
Several lead alloys are widely used. Solder, an alloy that is nearly half lead and half tin, is a material with a relatively low melting point that is used to join electrical components, pipes and other metallic items. Type metal, an alloy of lead, tin and antimony, is a material used to make the type used in printing presses and plates. Babbit metal, another lead alloy, is used to reduce friction in bearings.
Lead forms many useful compounds. Lead monoxide (PbO), also known as litharge, is a yellow solid that is used to make some types of glass, such as lead crystal and flint glass, in the vulcanizing of rubber and as a paint pigment. Lead dioxide (PbO2) is a brown material that is used in lead-acid storage batteries. Trilead tetraoxide (Pb3O4), also known as red lead, is used to make a reddish-brown paint that prevents rust on outdoor steel structures. Lead arsenate (Pb3(AsO4)2) has been used as an insecticide although other, less harmful, substances have now largely replaced it. Lead carbonate (PbCO3), also known as cerussite, is a white, poisonous substance that was once widely used as a pigment for white paint. Use of lead carbonate in paints has largely been stopped in favor of titanium oxide (TiO2). Lead sulfate (PbSO4), also known as anglesite, is used in a paint pigment known as sublimed white lead. Lead chromate (PbCrO4), also known as crocoite, is used to produce chrome yellow paint. Lead nitrate (Pb(NO3)2) is used to make fireworks and other pyrotechnics. Lead silicate (PbSiO3) is used to make some types of glass and in the production of rubber and paints.
Estimated Crustal Abundance: 1.4×101 milligrams per kilogram
Estimated Oceanic Abundance: 3×10-5 milligrams per liter
Number of Stable Isotopes: 3 (View all isotope data)
Ionization Energy: 7.417 eV
Oxidation States: +4, +2
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10