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:
“For even satire is a form of sympathy. It is the way our sympathy flows and recoils that really determines our lives. And here lies the vast importance of the novel, properly handled. It can inform and lead into new places our sympathy away in recoil from things gone dead. Therefore the novel, properly handled, can reveal the most secret places of life: for it is the passional secret places of life, above all, that the tide of sensitive awareness needs to ebb and flow, cleansing and freshening.”
—D.H. (David Herbert)
“Were you to converse with a king, you ought to be as easy and unembarrassed as with your own valet-de chambre; but yet every look, word, and action should imply the utmost respect.... You must wait till you are spoken to; you must receive, not give, the subject of conversation, and you must even take care that the given subject of such conversation do not lead you into any impropriety.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“I do not speak with any fondness but the language of coolest history, when I say that Boston commands attention as the town which was appointed in the destiny of nations to lead the civilization of North America.”
—Ralph Waldo Emerson (1803–1882)