Zinc




Zinc

MELTING POINT: 419°C
BOILING POINT: 907°C
DENSITY: 7.14 g/cm 3
MOST COMMON IONS: Zn 2+

Like many transition metals , zinc has been known in impure form since ancient times. Brass (copper and zinc) coins were used by Egyptians and Palestinians as early as 1400 B.C.E. The first purification of zinc probably occurred during India in the thirteenth century C.E . Although the origin of the name is unknown, it has been suggested that it derives from the German word Zincke, meaning "spike" or "tooth."

Zinc is a trace element (with an abundance of 0.0076%) in Earth's crust. Like the other elements in its family, zinc is found predominantly as a sulfide compound (ZnS). Pure zinc is a silver-white solid at room temperature. Like other metals , zinc conducts electricity and can be formed into wires or sheets. Some properties of zinc are quite different from those of the other transition metals—namely, its relatively low melting point, boiling point, and density. These different properties are attributed to zinc's full outermost subshell of electrons, which also causes it to be relatively unreactive.

Due to the low reactivity of zinc, its most common use is in anticorrosion coatings. Zinc is also often used to form alloys , including brass and commercial bronze. Pennies minted after 1983 are made of a core of zinc surrounded by copper. Historically, zinc was used by Alessandro Volta in 1800 to produce the first battery. Zinc ions, due to their low reactivity, are important biologically. In animals zinc is the most abundant metallic cofactor ; it is used by insulin in the regulation of glucose consumption and by hydrolytic enzymes. An adult human body contains 2 to 3 grams (0.071–0.106 ounces) of zinc.

SEE ALSO Cofactors ; Volta, Alessandro .

Thomas B. Rauchfuss

Amanda Lawrence

Bibliography

Greenwood, N. N., and Earnshaw, A. (1997). Chemistry of the Elements, 2nd edition. Boston: Butterworth-Heinemann.

Nechaev, I., and Jenkins, G. W. (1994). Chemical Elements: The Exciting Story of Their Discovery and of the Great Scientists Who Found Them. Jersey City, NJ: Parkwest.

Internet Resources

WebElements—Periodic Table. Available from http://www.webelements.com/ .



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