Lead is a soft but heavy metal. It has been known for a long time. Roman ruins contain many examples of lead used for water pipes. It was called plumbum. The English word plumber was derived from it. The symbol of lead is Pb.
Pure lead is bright and silvery but will tarnish in air. Aside from this tarnishing, lead will resist further corrosion much better than most metals. The density of lead is 11.3 grams per cubic centimeter, and its melting point is 327.4°C. Its atomic number is 82 and its atomic weight is 207.19 (207.21, 0=16). It has several isotopes, mainly 206, 207, and 208.
The most important lead ore is lead sulfide or galena. It is found in veins and usually with other metals. Flotation is used to concentrate the ore. Then by roasting, most of the sulfide is converted to lead oxide.
The widespread use of lead compounds in industry and the home makes it important that everyone be aware of lead poisoning, or plumbism. Acute poisoning from lead is very rare.
