Iodine

  • iodine, 53i
    sample of iodine.jpg
    iodine
    pronunciationn/ (eye-ə-dyn, -⁠din, -⁠deen)
    appearancelustrous metallic gray, violet as a gas
    standard atomic weight ar, std(i)126.90447(3)[1]
    iodine in the periodic table
    hydrogen helium
    lithium beryllium boron carbon nitrogen oxygen fluorine neon
    sodium magnesium aluminium silicon phosphorus sulfur chlorine argon
    potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton
    rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon
    caesium barium lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury (element) thallium lead bismuth polonium astatine radon
    francium radium actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson
    br

    i

    at
    telluriumiodinexenon
    atomic number (z)53
    groupgroup 17 (halogens)
    periodperiod 5
    blockp-block
    element category  reactive nonmetal
    electron configuration[kr] 4d10 5s2 5p5
    electrons per shell2, 8, 18, 18, 7
    physical properties
    phase at stpsolid
    melting point(i2) 386.85 k ​(113.7 °c, ​236.66 °f)
    boiling point(i2) 457.4 k ​(184.3 °c, ​363.7 °f)
    density (near r.t.)4.933 g/cm3
    triple point386.65 k, ​12.1 kpa
    critical point819 k, 11.7 mpa
    heat of fusion(i2) 15.52 kj/mol
    heat of vaporisation(i2) 41.57 kj/mol
    molar heat capacity(i2) 54.44 j/(mol·k)
    vapour pressure (rhombic)
    p (pa) 1 10 100 1 k 10 k 100 k
    at t (k) 260 282 309 342 381 457
    atomic properties
    oxidation states−1, +1, +3, +4, +5, +6, +7 (a strongly acidic oxide)
    electronegativitypauling scale: 2.66
    ionisation energies
    • 1st: 1008.4 kj/mol
    • 2nd: 1845.9 kj/mol
    • 3rd: 3180 kj/mol
    atomic radiusempirical: 140 pm
    covalent radius139±3 pm
    van der waals radius198 pm
    color lines in a spectral range
    spectral lines of iodine
    other properties
    natural occurrenceprimordial
    crystal structureorthorhombic
    orthorhombic crystal structure for iodine
    thermal conductivity0.449 w/(m·k)
    electrical resistivity1.3×107 Ω·m (at 0 °c)
    magnetic orderingdiamagnetic[2]
    magnetic susceptibility−88.7·10−6 cm3/mol (298 k)[3]
    bulk modulus7.7 gpa
    cas number7553-56-2
    history
    discovery and first isolationbernard courtois (1811)
    main isotopes of iodine
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    123i syn 13 h ε, γ 123te
    124i syn 4.176 d ε 124te
    125i syn 59.40 d ε 125te
    127i 100% stable
    129i trace 1.57×107 y β 129xe
    131i syn 8.02070 d β, γ 131xe
    135i syn 6.57 h β 135xe
    category category: iodine
    | references

    iodine is a chemical element with the symbol i and atomic number 53. the heaviest of the stable halogens, it exists as a lustrous, purple-black non-metallic solid at standard conditions that melts to form a deep violet liquid at 114 degrees celsius, and boils to a violet gas at 184 degrees celsius. however, it sublimes easily with gentle heat, resulting in a widespread misconception even taught in some science textbooks that it does not melt. the element was discovered by the french chemist bernard courtois in 1811. it was named two years later by joseph louis gay-lussac, after the greek ἰώδης "violet-coloured".

    iodine occurs in many oxidation states, including iodide (i), iodate (io
    3
    ), and the various periodate anions. it is the least abundant of the stable halogens, being the sixty-first most abundant element. it is the heaviest essential mineral nutrient. iodine is essential in the synthesis of thyroid hormones.[4] iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.

    the dominant producers of iodine today are chile and japan. iodine and its compounds are primarily used in nutrition. due to its high atomic number and ease of attachment to organic compounds, it has also found favour as a non-toxic radiocontrast material. because of the specificity of its uptake by the human body, radioactive isotopes of iodine can also be used to treat thyroid cancer. iodine is also used as a catalyst in the industrial production of acetic acid and some polymers.

  • history
  • properties
  • chemistry and compounds
  • occurrence and production
  • applications
  • biological role
  • precautions
  • references
  • bibliography

Iodine, 53I
Sample of iodine.jpg
Iodine
Pronunciationn/ (EYE-ə-dyn, -⁠din, -⁠deen)
Appearancelustrous metallic gray, violet as a gas
Standard atomic weight Ar, std(I)126.90447(3)[1]
Iodine in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Br

I

At
telluriumiodinexenon
Atomic number (Z)53
Groupgroup 17 (halogens)
Periodperiod 5
Blockp-block
Element category  Reactive nonmetal
Electron configuration[Kr] 4d10 5s2 5p5
Electrons per shell2, 8, 18, 18, 7
Physical properties
Phase at STPsolid
Melting point(I2) 386.85 K ​(113.7 °C, ​236.66 °F)
Boiling point(I2) 457.4 K ​(184.3 °C, ​363.7 °F)
Density (near r.t.)4.933 g/cm3
Triple point386.65 K, ​12.1 kPa
Critical point819 K, 11.7 MPa
Heat of fusion(I2) 15.52 kJ/mol
Heat of vaporisation(I2) 41.57 kJ/mol
Molar heat capacity(I2) 54.44 J/(mol·K)
Vapour pressure (rhombic)
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 260 282 309 342 381 457
Atomic properties
Oxidation states−1, +1, +3, +4, +5, +6, +7 (a strongly acidic oxide)
ElectronegativityPauling scale: 2.66
Ionisation energies
  • 1st: 1008.4 kJ/mol
  • 2nd: 1845.9 kJ/mol
  • 3rd: 3180 kJ/mol
Atomic radiusempirical: 140 pm
Covalent radius139±3 pm
Van der Waals radius198 pm
Color lines in a spectral range
Spectral lines of iodine
Other properties
Natural occurrenceprimordial
Crystal structureorthorhombic
Orthorhombic crystal structure for iodine
Thermal conductivity0.449 W/(m·K)
Electrical resistivity1.3×107 Ω·m (at 0 °C)
Magnetic orderingdiamagnetic[2]
Magnetic susceptibility−88.7·10−6 cm3/mol (298 K)[3]
Bulk modulus7.7 GPa
CAS Number7553-56-2
History
Discovery and first isolationBernard Courtois (1811)
Main isotopes of iodine
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
123I syn 13 h ε, γ 123Te
124I syn 4.176 d ε 124Te
125I syn 59.40 d ε 125Te
127I 100% stable
129I trace 1.57×107 y β 129Xe
131I syn 8.02070 d β, γ 131Xe
135I syn 6.57 h β 135Xe
Category Category: Iodine
| references

Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black non-metallic solid at standard conditions that melts to form a deep violet liquid at 114 degrees Celsius, and boils to a violet gas at 184 degrees Celsius. However, it sublimes easily with gentle heat, resulting in a widespread misconception even taught in some science textbooks that it does not melt. The element was discovered by the French chemist Bernard Courtois in 1811. It was named two years later by Joseph Louis Gay-Lussac, after the Greek ἰώδης "violet-coloured".

Iodine occurs in many oxidation states, including iodide (I), iodate (IO
3
), and the various periodate anions. It is the least abundant of the stable halogens, being the sixty-first most abundant element. It is the heaviest essential mineral nutrient. Iodine is essential in the synthesis of thyroid hormones.[4] Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.

The dominant producers of iodine today are Chile and Japan. Iodine and its compounds are primarily used in nutrition. Due to its high atomic number and ease of attachment to organic compounds, it has also found favour as a non-toxic radiocontrast material. Because of the specificity of its uptake by the human body, radioactive isotopes of iodine can also be used to treat thyroid cancer. Iodine is also used as a catalyst in the industrial production of acetic acid and some polymers.