Chemical Elements: Properties and Uses of Zinc and Iodine

Iodine comes from the word "ioeides" or violet. Its symbol is "I" and is a relatively rare element. It was first isolated from seaweed residues in 1811 by Bernard Courtois, a French manufacturer of saltpeter but was further established in 1813 by the French chemist Joseph Louis Gay-Lussac, who also gave iodine its name. This discovery was confirmed and announced by the French chemists Charles Desormes and Nicholas Clement. Iodine was formerly derived from seaweeds and is now produced from oil-well brines.

Iodine is poisonous in its pure form. It is sparingly soluble in water. It comes as black shiny crystal that dissolves in alcohol. The deficiency of this element in human diet causes thyroid trouble. To counteract this deficiency, most table salts are now prepared "iodized".

Iodine salts are used in dyes, photographic material, disinfectant, radioactive tracer and also an essential element for humans.

Zinc

Zinc was discovered in 1746 by Andreas Sigismund Marggraf of Germany by isolating the pure metal through heating calamine and charcoal. It comes from the German word "zink" for tin and its symbol is "Zn". Zinc is bluish-white, lustrous metallic element. Pure zinc is insoluble in acids, alcohol and alkalis. In humans, zinc is important for growth and development.

Zinc is a reasonable conductor of electricity, and burns in air at high temperature. It is used as a zinc oxide to stabilize rubber and plastic. It is also used for galvanized iron to prevent it from rusting. Also in gutter, pipes, paints, cosmetics, soaps, inks, textiles, roofs, alloys and batteries.