Iodine (I)
| Atomic Number | 53 |
|---|---|
| Atomic Mass | 126.904473 u |
| Category | Diatomic nonmetal |
| Electron Config | [Kr] 4d¹⁰ 5s² 5p⁵ |
| Appearance | lustrous metallic gray, violet as a gas |
| Density (STP) | 4940 g/L |
| Melting Point | 386.85 K |
| Boiling Point | 457.4 K |
| Electronegativity | 2.66 (Pauling) |
| Ionization Energy | 1008.4 kJ/mol |
| Atomic Radius | 140 pm |
| Crystal Structure | Base Orthorhombic |
| Discovered By | Bernard Courtois (1811) |
Brief Introduction
Iodine (I) is a lustrous, purple-black non-metallic solid that sublimes readily to form a purple vapor. It is the heaviest stable halogen and essential for human health. Key details about Iodine (I) are as follows:
Uses: Used in medical applications (antiseptics, disinfectants, radiological contrast media, radioiodine therapy), iodized salt (prevents iodine deficiency), animal feed supplements, LCD displays (polarizing films), photography (silver iodide), catalysts, and in various organic synthesis reactions.
Production/Extraction: Extracted from brine (especially from Chilean nitrate deposits and Japanese seaweed processing) or from underground brines associated with oil and gas production. Chile and Japan are historically major producers; China now leads production.
History: Discovered by Bernard Courtois in 1811 while extracting sodium and potassium from seaweed ash. Named by Joseph Louis Gay-Lussac from Greek "iodes" (violet) due to the color of its vapor. First element isolated from a living organism.
Health Effects & Safety: Essential micronutrient for thyroid hormone synthesis (thyroxine). Deficiency causes goiter and mental retardation (cretinism); iodized salt has largely eliminated deficiency in developed countries. Elemental iodine is corrosive and toxic in large amounts. Radioactive I-131 is used medically but is also a hazardous fission product.
Price/Market: Moderate pricing; supply influenced by Chilean nitrate operations and brine extraction. Medical and industrial demand relatively stable. Iodized salt programs drive significant consumption.
Properties: Sublimes readily at room temperature, forms purple vapor, only non-metallic element that is solid and lustrous at room temperature, exhibits -1, +1, +5, and +7 oxidation states, forms dark purple solutions in organic solvents, and stains skin and tissue.
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