Lead is a chemical element in the carbon group with symbol Pb (from Latin: plumbum) and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid.
Lead is used in building construction, lead-acid batteries, bullets and shot, weights, as part of solders, pewters, fusible alloys, and as a radiation shield. Lead has the highest atomic number of all of the stable elements, although the next higher element, bismuth, has a half-life that is so long (much longer than the age of the universe) that it can be considered stable. Its four stable isotopes have 82 protons, a magic number in the nuclear shell model of atomic nuclei.
Lead, at certain contact degrees, is a poisonous substance to animals, including humans. It damages the nervous system and causes brain disorders. Excessive lead also causes blood disorders in mammals. Like the element mercury, another heavy metal, lead is a neurotoxin that accumulates both in soft tissues and the bones. Lead poisoning has been documented from ancient Rome, ancient Greece, and ancient China.
Read more about Lead: Characteristics, Compounds, History, Occurrence, Health Effects
Famous quotes containing the word lead:
“Once lead this people into war and they will forget there ever was such a thing as tolerance.”
—Woodrow Wilson (1856–1924)
“It is sometimes called the City of Magnificent Distances, but it might with greater propriety be termed the City of Magnificent Intentions.... Spacious avenues, that begin in nothing, and lead nowhere; streets, mile-long, that only want houses, roads, and inhabitants; public buildings that need but a public to be complete; and ornaments of great thoroughfares, which only lack great thoroughfares to ornament—are its leading features.”
—Charles Dickens (1812–1870)
“There was ... a large, shaggy dog, whose nose, report said, was full of porcupine quills. I can testify that he looked very sober. This is the usual fortune of pioneer dogs, for they have to face the brunt of the battle for their race.... When a generation or two have used up all their enemies’ darts, their successors lead a comparatively easy life. We owe to our fathers analogous blessings.”
—Henry David Thoreau (1817–1862)