Iodine



= = (Element Abbreviation: I)

__Chemical Characteristics:__ Iodine is the most electropositive halogen and the least reactive of the halogens, even though it does form compounds with many elements.

__Physical Characteristics:__ • Iodine is a shiny, non-metallic, grayish-black flaky substance in its halogen solid form. In gas form it is violet. • Physical state (at 20o C and 1 atom) is solid • Molar volume is 25.74 cm3/mole • The average atomic mass of Iodine is 126.9045 amu • Boiling point is 365.7o F (458.55 K or 185.4o C) • Vaporizes at a temperature of 20.752 kJ/mol • Melting point is 236.3o F (386.65 K or 113.5o C)

__Found in nature?__ Iodine can be found both on land and in the sea, often in sodium and potassium compounds. The world production of iodine is around 12 tons, and its primary producing areas are Chile and Japan.

__Recovered and purified?__ Iodine is found in an aqueous solution, which contains iodide. To recover the iodine the solution is passed through a specialized filter that catches the iodine ion. Iodine can then be obtained off of the filter.

__How it is used?__ • Iodide and thyroxin, which contain iodine, are used internally in medicines. • A solution of KI and iodine in alcohol is used as a disinfectant for external wounds. • Silver iodide is used in photography • Iodine can be an important nutrient, for example it is added to table salt and it helps stop goiter, which causes Derbyshire neck • It is often used to give a deep blue color in starch solutions

__Products?__ Iodine is used in many different sorts of products: • Many sanitation and cleaning compound manufacturers use iodine in disinfectant solutions. These solutions are very toxic and corrosive to the eyes and irritating, but not corrosive, to the skin. • Pharmaceutical companies potassium iodide expectorant compounds, also known as x-ray contrast media compounds. • Animal food manufacturers make iodine derivatives, which are put in animal feeds to supply nutritional iodine, and to prevent lack of iodine related diseases in cattle and poultry. • Many dye and ink manufacturers use iodine to make aniline and phthalein dyes. It is also used in fluorescent paints to make very bright colors. • Photographic film manufacturers mix potassium iodide and a soluble silver compound to make silver iodide for black and white film. • And the list goes on. A few others are: o Iodized table salt o Electric light bulbs o Water purification o Swimming pool sanitation Iodine is not a flammable product so you don’t need to be too cautious when disposing of any of these products, but it is strongly oxidizing and some combustible materials may ignite on contact with iodine. So when disposing of any iodine products, be sure they are not disposed with or anywhere near combustible or reactive materials.

__Nutrition Importance:__ Iodine is an important nutrient for our bodies. Lack of it can cause a disease known as Derbyshire neck, which is an inflammation of the thyroid gland in the neck. The recommended daily amount is about .15 mg per day and a tolerable upper limit of 1.1 mg per day. Symptoms of this disease, also known as hypothyroidism, include extreme fatigue, mental slowing, depression, weight gain, and low basal body temperatures. Iodine deficiency is also the leading cause of preventable mental retardation. Due to the addition of iodine in table salt this problem has been mostly eliminated in wealthier nations, yet poorer developing countries still see this as a large public health problem.

Brodie W.