Zinc

Zinc (chemical symbol: Zn) is a metal with atomic number 30. It is silvery-white in color with a slight bluish tinge when pure. It belongs to the transition metals group in the periodic table. Its atomic weight is approximately 65.4.

Zinc is brittle at room temperature and cannot be rolled or shaped. However, when heated to moderate temperatures it becomes malleable. It has a lower melting point than most other metals, making it suitable for die casting.

Chemical properties

Zinc is a reactive metal that interacts with air. When exposed to the atmosphere, a thin layer of zinc oxide and zinc carbonate forms on its surface. This layer protects the underlying metal from further oxidation. This property is the basis for zinc's most important use. Zinc reacts with acids and bases to produce hydrogen gas.

Applications

The largest portion of extracted zinc is used for galvanization—coating iron or steel with a layer of zinc to protect it from corrosion. This is done through hot-dipping the steel in molten zinc or through electroplating. Zinc is also an important component of alloys: zinc and copper produce brass, which is used in pipes, musical instruments, and keys.

Zinc oxide is used in the rubber, paint, and cosmetics industries, including in sunscreen products. Some batteries—such as zinc-carbon and zinc-air cells—use zinc as an anode.

Role in nutrition

Zinc is a micronutrient essential to humans, animals, and plants. It is part of hundreds of enzymes and proteins involved with DNA. Zinc levels in food affect childhood growth and immune function. Food sources of zinc include meat, legumes, nuts, and shellfish. Excessive zinc intake can be harmful, particularly as it interferes with copper absorption.

Production

Zinc is rarely found in nature as a pure metal. The most common ore is sphalerite (zinc sulfide). Production begins with roasting the ore to convert the sulfide to oxide, followed by chemical or thermal processing to extract the metal. Much zinc is recycled without loss of quality.