CHEMICAL SYMBOL ( I )

Discovery of Iodine

• Iodine was discovered by Bernard Courtois in 1811 in France. Courtois was trying to extract potassium chloride from seaweed. After crystallizing the potassium chloride, he added sulfuric acid to the remaining liquid. This, rather surprisingly, produced a purple vapor, which condensed into dark crystals. These were the first crystals of iodine Iodine’s name comes from the Greek work ‘iodes’ meaning violet.

Harmful effects

• In small doses, iodine is slightly toxic and it is highly poisonous in large amounts. Elemental iodine is an irritant which can cause sores on the skin. Iodine vapor causes extreme eye irritation.

Characteristics

• Iodine is a bluish-black, lustrous solid. Although it is less reactive than the elements above it in group 17 (fluorine, chlorine and bromine) it still forms compounds with many other elements. Although iodine is a non-metal, it displays some metallic properties.

Uses of Iodine

• Iodine is important in medicine, in both radioactive and non-radioactive forms. Iodide and thyroxin, which contains iodine, are used inside the body. A solution containing potassium iodide (KI) and iodine in alcohol is used to disinfect external wounds Iodine is sometimes added to table salt to prevent thyroid disease. Iodine’s other uses include catalysts, animal feeds and printing inks and dyes.

CLASSIFICATION

• Iodine is a halogen and a nonmetal
• Color bluish-black solid, purple vapor
• Atomic weight: 126.9045
• State: solid
• Electron configuration: [Kr] 4d10 5s2 5p5
• Atomic Number: 53
• Atomic Mass: 126.90447u
• Density 4.93 g.cm-3 at 20°C
• Period 5

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