Lead

Element Name: Lead
Atomic Number: 82
Atomic Mass: 207.2
Atomic Symbol: Pb
Melting Point: 327.46° C
Boiling Point: 1749° C

Lead is a soft, malleable, bluish-silver metal that tarnishes in moist air. Unlike other metals, lead is a poor conductor of electricity and is very soft, especially considering its density. It is very resistant to corrosion and highly toxic when inside the body – an insidious combination. Lead is a member of the carbon family, so it embeds itself in soft tissue, causing brain and nervous system disorders. The chemical symbol of lead, Pb, comes from the Latin word for the same substance, Plumbum. Its modern name comes from an Anglo-Saxon word that sounds approximately the same as “lead”. It’s the heaviest stable nuclide (thanks to lead 208 having a “magic” number for both its neutron and proton count). Lead has four natural isotopes, and 38 isotopes total. Lead is usually in the +2 or +4 oxidation states, but +3, +1, -1, -2, and -4 have all been shown to exist.

Interesting Facts:

Lead’s low melting point made it a potent medieval weapon when defending castles. Pouring molten lead over castle ramparts would cause horrific damage to besiegers. Lead pipes are so long lived that some of them in Rome were there at the time of the Roman Empire. This is possible since lead is soft enough to hammer into place if leaks form and has a low enough melting point that adding extra material is viable when the pipe gets too thin. Wine in Rome was sometimes stored in lead containers. Any vinegar present would react with the vessel and create lead acetate, a toxic sweetener. The first printing press used a lead-antimony-tin alloy for its letterings. White paint used to contain lead, but has since been banned in most places because of the harmful fumes that came off it. Pencil lead (graphite) is not made from lead. Tetraethyl lead is incredibly toxic. Lead is associated with the god Saturn, the Roman god of the wealth, time, and agriculture.

Sources:

Lead does not normally appear in its elemental form. The majority of lead is obtained via minerals, usually in conjunction with copper, zinc, and silver. Lead is the principal element in galena, cerussite, and angelsite. Boulangerite is another mineral related to galena where significant amounts of lead can be found, but the rest of lead production comes from the purification of other minerals. Lead can be found at 16 parts per million, making it fairly abundant, especially when compared to elements of similar atomic weight. Approximately 4700 thousand tons of lead was produced in 2015, with the top producers being China, Australia, and the United States. Of those top contributors, China was by far the largest, mining 2300 thousand tons.

Industrial Uses:

Lead’s industrial uses are getting reduced steadily due to its toxicity. Tetraethyllead was once an additive in gasoline to reduce knocking in cars (a phenomenon that made it difficult to get up steep hills). Due to environmental concerns this practice has stopped. Lead’s low cost spurs most of its current usage in spite of health concerns. Lead is used in bullets (wherein the goal is to make the receiver suffer damage), but is seeing some pushback. In uses like hunting, lead is discouraged because of the long-term environmental damage it can do. One use of lead that has seen no reduction of use is lead-acid batteries. They grant reliable voltage and never come in direct contact with the environment (because they are usually covered and placed in areas rarely accessed by the outside). Lead plates and lead glass is used to protect people from sources of radiation. The size of the lead molecule combined with its density causes it to be an excellent choice for this application.

References:

“Lead.” Chemicool Periodic Table. Chemicool.com, 29 Dec. 2012. Web. 26 July
2016.
“Lead.” Wikipedia. Wikimedia Foundation, n.d. Web. 26 July 2016.
“Facts About Lead.” Livescience. Livescience.com, 29 Aug. 2013. Web. 26 July 2016.
Gray, Theodore W., and Nick Mann. The Elements: A Visual Exploration of Every
Known Atom in the Universe. New York: Black Dog & Leventhal, 2009. Print.
Aldersey-Williams, Hugh. Periodic Tales: A Cultural History of the Elements, from
Arsenic to Zinc. New York: Ecco, 2011. Print.