Lead - the Element

Lead is categorized as one of the heavy metals, having atomic number 82 and symbol Pb. It is a malleable and soft metal and when it melts into liquid, it gets a shiny chrome-silver luster. However, when it is just cut, it has a bluish-white color. When exposed to air, it changes into a dull, gray color.

History of Lead
It is interesting that the Latin word Plumbum is the full form of Pb, the symbol of lead. Plumbum in Latin was used to refer to 'soft metals'. History of this metal dates back to thousands of years. Lead is easily extracted and found in lots of places. Lead was used with antimony and arsenic in the early Bronze Age. Furthermore, lead in molten form was used by the Romans to strengthen iron pins, that were used to hold the limestone blocks in monumental buildings.

Characteristics of Lead
Lead, a dense and ductile metal, is a poor electrical conductor. It has an atomic weight of 207.2 amu. The melting point of lead is 327.46 degrees centigrade and the boiling point is 1749 degrees centigrade. A great property of this metal, which probably makes it the best bet for industrial and chemical purposes, is its corrosion-resistant nature. It is extensively used to store corrosive chemicals, like sulfuric acid. It is also heavily used in the construction industry because of its malleability. It is frequently used for external coverings of roof joints. But, this metal and its compounds are poisonous, which can prove dangerous for human health.

Mining and Occurrence
Lead in its metallic form is rarely found naturally. It is usually extracted from zinc, silver and mostly from copper ore. Galena (PbS) is the main lead mineral, containing 86.6% of it. The common varieties of lead are cerussite ( PbCO₃) and anglesite (PbS0₄).

The process of obtaining pure lead after the main mineral is extracted, is quite complicated. A coke-fired blast-furnace is used to reduce lead oxide from the roasting process. Lead is mostly converted into metallic form through this process. This form of lead still has considerable contaminants of bismuth, zinc, copper, arsenic, gold, silver and antimony. All contaminants, except silver, gold and bismuth are oxidized after a treatment in the reverberatory furnace (using air, steam and sulfur). Then, the oxidized contaminants are skimmed off, after they float to the top. Pure lead can be obtained by processing smelted lead electrolytically through the Betts process.

The countries where lead is produced (as of 2008) are Australia, China, the USA, Peru, Canada, Mexico, Sweden, Morocco, South Africa and North Korea. Out of these, Australia, China and the United States are produce more than half of the primary production.

Various Uses of Lead
Lead is used in a variety of fields, ranging from industry to marine engineering, to sports equipment. It is also the main element for the lead-acid battery, which is extensively used as a car battery. If added to brass, it helps lessen machine tool wear. In X-ray rooms, lead is used as a shield against radiation. It is frequently used in sculptures and statues. Lead is also used in the making of the ballast keel of sailboats, because of its high density and corrosion-resistant properties. Due to the aforementioned qualities, lead is also widely used in scuba-diving weight belts. In liquid form, lead is also used as a coolant. Lead is also a component of Polyvinyl Chloride (PVC) plastic, which is used to coat electrical wires.

Effects on Human Body
Lead, due to its poisonous properties can cause damage to the nervous connections, blood and brain disorders in children. In the event of long term exposure to lead or its salts, nephropathy and colic-like abdominal pain can occur. The main target for lead toxicity, is the nervous system. Kidneys and brain can undergo serious damage, in case of continuous exposure to high-level of lead and it can also be fatal. If pregnant women are highly exposed to lead, it could result in a miscarriage. In short, lead has or can have an affect on almost every organ system of the body. Low level exposure to this element can decrease the cognitive capacity of children.

There are many more dimensions to this wonder metal. Discretionary use of this element can help reap the best of outcomes.