The Element Lead: Characteristics and Uses

Lead is categorized as one of the heavy metals, having atomic number 82 and its symbol is Pb. It is a malleable and soft metal and when it melts and turns 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.

It is interesting to know 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.

It was used with antimony and arsenic in the early Bronze Age. Furthermore, in molten form, it was used by the Romans to strengthen iron pins, which were used to hold the limestone blocks in monumental buildings.

Characteristics

It is a dense and ductile metal, and is a poor electrical conductor. It has an atomic weight of 207.2 amu. The melting point is 327.5ºC (600.65ºK) and the boiling point is 1750ºC (2023.15ºK). 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 or even fatal to human health.

Mining and Occurrence

In its metallic form, it is rarely found naturally. It is usually extracted from zinc, silver, and mostly from copper ore. Galena (PbS) is the main mineral containing 87% of lead. Its common varieties 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 still has considerable contaminants of bismuth, zinc, copper, arsenic, gold, silver & 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 metal can be obtained by processing smelted lead electrolytically through the Betts process.

The countries where this metal 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 produce more than half of the primary production.

Uses

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, it is used as a shield against radiation.

It is frequently used in making sculptures and statues. The metal 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, it is also widely used in scuba diving weight belts. In its liquid form, it can be used as a coolant.

It is a component of Polyvinyl Chloride (PVC) plastic, which is used to provide a coating to electrical wires.

Effects on the Human Body

Lead, due to its poisonous properties, can cause damage to the nervous system. It is harmful enough to cause blood and brain disorders in children. In the event of long-term exposure to the metal or its salts, nephropathy or colic-like abdominal pain can occur.

The main target of toxicity is the nervous system. The kidneys and brain can undergo serious damage, in case of continuous exposure to this metal, and it can also be fatal. If pregnant women are highly exposed to it, it could result in a miscarriage.

Low-level exposure to this element can decrease the cognitive capacity of children. In short, lead can have an adverse effect on almost every organ of the body system. However, on the positive side, discretionary use of this element can help reap the best of outcomes too.