Iodine PDF

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Summary

In depth discussion about element Iodine...

Description

Iodine

Symbol: I

Atomic Number: 53

A black, shiny, crystalline solid. When heated, iodine sublimes to form a purple vapour.

Iodine is a nonmetal. It is an element in group 17/7A on the periodic table, therefore it is a halogen, and halogens are nonmetals.

Physical properties

Iodine is one of the most striking and beautiful of all elements. As a solid, it is a heavy, grayish-black, metallic-looking material. When heated, it does not melt. Instead, it sublimes. Sublimation is the process by which a solid turns directly to a gas without first melting. The resulting iodine vapor has a violet color and a harsh odor. If a cold object, such as an iron bar, is placed in these vapors, iodine changes back to a solid. It forms attractive, delicate, metallic crystals.

Iodine dissolves only slightly in water. But it dissolves in many other liquids to give distinctive purple solutions. If heated under the proper conditions, it can be made to melt at 113.5°C (236.3°F) and to boil at 184°C (363°F). The density of the element is 4.98 grams per cubic centimeter.

Occurrence in nature

Iodine is not very abundant in the Earth's crust. Its abundance is estimated to be about 0.3 to 0.5 parts per million. It ranks in the bottom third of the elements in terms of abundance. It is still more common than cadmium, silver, mercury, and gold. Its abundance in seawater is estimated to be even less, about 0.0003 parts per million.

Uses and compounds

About two-thirds of all iodine and its compounds are used in sanitation systems or in making various antiseptics and drugs. Iodine is also used to make dyes, photographic film, and specialized soaps. It is used in some industries as a catalyst. A catalyst is a substance used to speed up or slow down a chemical reaction. The catalyst does not undergo any change itself during the reaction.

Health effects

Iodine can have both favorable and unfavorable effects on living organisms. It tends to kill bacteria and other disease-causing organisms. In fact, this property leads to its use in sanitation systems and as an antiseptic. An antiseptic is a chemical that stops the growth of germs. Not so long ago, tincture of iodine was one of the most popular antiseptics. It was applied to cuts and wounds to prevent infection. Tincture is a solution made by dissolving some substance (such as iodine) in alcohol rather than in water. Today, tincture of iodine has been replaced by other antiseptics.

One reason that tincture of iodine is used less today is that it can also cause problems. In higher doses, iodine can irritate or burn the skin. It can also be quite poisonous if taken internally.

Iodine kills bacteria and other disease-causing organisms.

References:

Kaiho, T. (2015). Iodine Chemistry and applications Title of work: Physical Properties of Iodine. Hoboken, New Jersey: John Wiley & Sons, Inc.

ChemistryExplained. (n.d.). Retrieved September 20, 2017 from ChemistryExplained: http://www.chemistryexplained.com/elements/C-K/Iodine.html#ixzz4tCLvcG8

Clarke, S. H. (March 2006). Iodine Disinfection in the Use of Individual Water Purification Devices. Retrieved from

https://phc.amedd.army.mil/PHC%20Resource%20Library/Iodine%20Disinfection%20in%20the%20Use %20of%20Individual%20Water%20Purification%20Devices.pdf...