Iodine is a chemical element wi seembol I an atomic nummer 53. The hiviest o the stable halogens, it exeests as a lustrous, purpie-black nan-metallic solit at staundart condeetions that sublimes readily tae form a violet gas. The elemental form wis diskivert bi the French chemist Bernard Courtois in 1811. It wis named twa years later bi Joseph Louis Gay-Lussac frae this property, efter the Greek ἰώδης "violet-coloured".
Iodine, 53I |
| Iodine |
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| Pronunciation | (EYE-ə-dyne, -din, -deen) |
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| Appearance | lustrous metallic gray, violet as a gas |
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| Standard atomic weight Ar, std(I) | 7002126904470000000♠126.90447(3)[1] |
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| Mass number | I: |
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| Iodine in the periodic cairt |
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|
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| Atomic nummer (Z) | 53 |
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| Group | group 17 (halogens) |
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| Period | period 5 |
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| Block | p-block |
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| Element category | Reactive nonmetal |
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| Electron confeeguration | [Kr] 4d10 5s2 5p5 |
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| Electrons per shell | 2, 8, 18, 18, 7 |
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| Pheesical properties |
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| Phase at STP | solit |
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| Meltin pynt | 386.85 K (113.7 °C, 236.66 °F) |
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| Bylin pynt | 457.4 K (184.3 °C, 363.7 °F) |
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| Density (near r.t.) | 4.933 g/cm3 |
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| Treeple pynt | 386.65 K, 12.1 kPa |
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| Creetical pynt | 819 K, 11.7 MPa |
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| Heat o fusion | (I2) 15.52 kJ/mol |
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| Heat o vapourisation | (I2) 41.57 kJ/mol |
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| Molar heat capacity | (I2) 54.44 J/(mol·K) |
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Vapour pressur (rhombic)
| P (Pa)
|
1
|
10
|
100
|
1 k
|
10 k
|
100 k
|
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| at T (K)
|
260
|
282
|
309
|
342
|
381
|
457
|
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|
| Atomic properties |
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| Oxidation states | −1, +1, +3, +4, +5, +6, +7 strangly acidic |
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| Electronegativity | Pauling scale: 2.66 |
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| Atomic radius | empirical: 140 pm |
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| Covalent radius | 139±3 pm |
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| Van der Waals radius | 198 pm |
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| Spectral lines o iodine |
| Ither properties |
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| Naitural occurrence | I: Primordial |
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| Creestal structur | orthorhombic |
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| Thermal conductivity | 0.449 W/(m·K) |
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| Electrical resistivity | 1.3×107 Ω·m (at 0 °C) |
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| Magnetic orderin | diamagnetic[2] |
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| Bulk modulus | 7.7 GPa |
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| CAS Nummer | 7553-56-2 |
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| History |
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| Diskivery | Bernard Courtois (1811) |
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| First isolation | Bernard Courtois (1811) |
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| Main isotopes o iodine |
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|
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| Decay modes in parentheses are predictit, but hae nae yet been observed |
| | references |
Iodine occurs in mony oxidation states, includin iodide (I−), iodate (IO−
3), an the various periodate anions. It is the least abundant o the stable halogens, bein the saxty-first maist abundant element. It is even less abundant nor the sae-cried rare yirds. It is the hiviest essential mineral nutrient. Iodine is essential in the synthesis o thyroid hormones.[3] Iodine deficiency affects aboot twa billion fowk an is the leadin preventable cause o intellectual disabilities.
The dominant producers o iodine the day are Chile an Japan. Iodine an its compoonds are primarily uised in nutreetion. Due tae its heich atomic nummer an ease o attachment tae organic compoonds, it haes an aw found favour as a nan-toxic radiocontrast material. Acause o the speceeficity o its uptak bi the human bouk, radioactive isotopes o iodine can an aw be uised tae treat thyroid cancer. Iodine is an aw uised as a catalyst in the industrial production o acetic acid an some polymers.
