Zinc
. Zinc, symbol Zn, bluish-white metallic element that has many industrial applications. Zinc is one of the transition elements of the periodic table . The atomic number of zinc is 30. The ores of zinc have long been known, but zinc was not recognized as a separate element until 1746, when the German chemist Andreas Sigismund Marggraf isolated the pure metal by heating calamine and charcoal. PROPERTIES AND OCCURRENCE Pure zinc is a crystalline metal, insoluble in hot and cold water and soluble in alcohol , acids, and alkalies . It is extremely brittle at ordinary temperatures, but becomes malleable between 120° and 150° C (248° and 302° F) and may be rolled into sheets between heated rollers. Zinc is unaffected by dry air; in moist air it is oxidized and becomes coated with a carbonate film that protects it from further corrosion. Zinc melts at about 420° C (about 788° F), boils at about 907° C (about 1665° F), and has a specific gravity of 7.14. The atomic weight of zinc is 65.38. Zin