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:
“Methods of thought which claim to give the lead to our world in the name of revolution have become, in reality, ideologies of consent and not of rebellion.”
—Albert Camus (1913–1960)
“For some years now, there has been proof that the devastating effects of the traumatization of children take their inevitable toll on society—a fact that we are still forbidden to recognize. This knowledge concerns every single one of us, and—if disseminated widely enough—should lead to fundamental changes in society; above all, to a halt in the blind escalation of violence.”
—Alice Miller (20th century)
“To rescue our children we will have to let them save us from the power we embody: we will have to trust the very difference that they forever personify. And we will have to allow them the choice, without fear of death: that they may come and do likewise or that they may come and that we will follow them, that a little child will lead us back to the child we will always be, vulnerable and wanting and hurting for love and for beauty.”
—June Jordan (b. 1939)