Iodine
Reactive Nonmetal
Iodine (I) is a chemical element with atomic number 53, classified as a reactive nonmetal. At room temperature it is a solid. It was discovered in 1811 by Bernard Courtois.
Properties
- Atomic number
- 53
- Atomic mass
- 126.9 u
- Category
- Reactive Nonmetal
- Group
- 17
- Period
- 5
- Block
- p-block
- Electron configuration
- [Kr] 4d¹⁰ 5s² 5p⁵
- Phase at STP
- Solid
- Density
- 4.93 g/cm³
- Melting point
- 386.85 K (113.7 °C)
- Boiling point
- 457.4 K (184.3 °C)
- Electronegativity
- 2.66
- Atomic radius
- 115 pm
- Ionization energy
- 10.451 eV
- Discovery
- 1811 · Bernard Courtois
Common uses
Antiseptics, table salt, medical imaging, photography
Did you know?
Essential for thyroid function and deficiency causes goiter.
Compounds you can make with iodine
Iodine appears in one compound in our periodic table sandbox. Each one is a real substance with its true chemical formula — combine the right elements in the right ratio below to discover it.
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KI
Potassium Iodide
Added to table salt to prevent iodine deficiency; also protects the thyroid.