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:
“Horrible experiences lead us to wonder whether the person who experiences them might not be something horrible.”
—Friedrich Nietzsche (1844–1900)
“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)
“‘Whence thou return’st, and whither wentst, I know;
For God is also in sleep; and dreams advise,
Which he hath sent propitious, some great good
Presaging, since, with sorrow and heart’s distress,
Wearied I fell asleep: but now lead on;
In me is no delay; without thee here to stay,
Is to go hence unwilling; thou to me
Art all things under Heaven, all places thou,”
—John Milton (1608–1674)