Glossary

Lead is a dense, soft, bluish-gray metal with the chemical symbol Pb (from the Latin plumbum) and an atomic number of 82. It is one of the heaviest and most malleable metals, known for its high density, corrosion resistance, and low melting point (327.5°C or 621.5°F). Lead has been used by humans for thousands of years — from ancient plumbing and pigments to modern batteries and radiation shielding — though its use has declined due to health and environmental concerns.

In its pure form, lead is easily shaped, stretched, or cast, making it extremely versatile for industrial use. It tarnishes slowly when exposed to air, forming a protective oxide coating that prevents deeper corrosion, similar to how zinc or aluminum behave. Unlike most metals, lead is non-sparking, highly resistant to acids, and an excellent sound and vibration dampener, which is why it’s been used historically in pipes, roofing, ammunition, and protective barriers.

The most common modern application for lead is in lead-acid batteries, which power vehicles and provide backup energy for uninterruptible power systems (UPS). In this form, lead is used both as lead dioxide (PbO₂) at the positive plate and spongy lead (Pb) at the negative plate, with sulfuric acid acting as the electrolyte. This chemistry makes lead indispensable in battery technology, particularly for starting engines and providing reliable, recyclable energy storage.

Lead is also used in radiation shielding because of its high density and ability to absorb X-rays and gamma rays. Hospitals, dental offices, and nuclear facilities use lead-lined walls, aprons, and containers for protection. Additionally, it finds use in weights, counterbalances, solder, and cable sheathing—applications that rely on its weight, flexibility, and low melting point.

However, lead is toxic to humans and animals. It accumulates in soft tissues and bones, interfering with the nervous system, kidneys, and reproductive health. Chronic exposure—especially from lead paint, contaminated water, or industrial emissions—can cause serious developmental and neurological damage. As a result, lead has been phased out from gasoline, paint, plumbing, and most consumer products in favor of safer alternatives.

Lead is primarily obtained from the mineral galena (lead sulfide, PbS), though it often occurs with other metals like zinc, silver, and copper. The metal is extracted through smelting and refining processes, after which it can be alloyed or purified for specific uses.