Zinc
Zinc, a bluish-white, lustrous, metallic element. Zinc is one of the most widely used of all metals in industry. Zinc occurs in nature in a variety of ores, the most common being sphalerite (zinc sulfide). Canada leads the world in the mining of zinc, followed by Australia, Peru, and China. The leading smelters of zinc are Canada, Japan, and China.
As part of the extraction process, zinc ores are usually roasted to convert the zinc in the ore into zinc oxide. Most zinc produced today is obtained from the oxide by an electrolytic process. In this process, the zinc oxide is dissolved in an acid and the resulting solution pumped into an electrolytic cell. An electric current is applied between the electrodes in the cell, causing the zinc in the solution to be deposited on the negative electrode.
When metallic zinc is exposed to moist air, its surface changes into basic zinc carbonate, which protects the underlying zinc from further chemical reactions. For this reason, zinc is often used to coat iron or steel to protect them from corrosion. Metals thus treated are said to be galvanized. Zinc is used in making brass, nickel silver, and die-casting alloys. It is also used to make the negative electrodes in several types of electric batteries. United States pennies issued after 1981 are composed largely of zinc.
Zinc oxide is used as a paint pigment; to reinforce rubber products; to coat paper; and in the manufacture of ceramics and cosmetics. It is also used in powders and ointments for skin ailments.
Zinc ores were used for making brass in ancient times, but zinc was not recognized as a distinct element. Zinc was first extracted from its ores in the Far East in later medieval times. In 1746 zinc was rediscovered in Europe by the German chemist Andreas Sigismund Marggraf.
Symbol: Zn. Atomic number: 30. Atomic weight: 65.39. Melting point: 787.1 F. (419.5 C.). Boiling point: 1,662.8 F. (906 C.). Specific gravity: 7.14. Zinc belongs to Group II B of the Periodic Table and has a valence of +2.