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Pronunciation | (EYE-ə-dyne, -din, -deen) |
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Appearance | lustrous metallic gray solid, black/violet liquid, violet gas |
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| 126.90447(3)[1] |
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Atomic number (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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Electron configuration | [Kr] 4d10 5s2 5p5 |
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Electrons per shell | 2, 8, 18, 18, 7 |
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Phase at STP | solid |
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Melting point | (I2) 386.85 K (113.7 °C, 236.66 °F) |
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Boiling point | (I2) 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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Triple point | 386.65 K, 12.1 kPa |
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Critical point | 819 K, 11.7 MPa |
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Heat of fusion | (I2) 15.52 kJ/mol |
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Heat of vaporization | (I2) 41.57 kJ/mol |
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Molar heat capacity | (I2) 54.44 J/(mol·K) |
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Vapor pressure (rhombic)
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
260 |
282 |
309 |
342 |
381 |
457 |
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Oxidation states | −1, 0, +1, +2,[2] +3, +4, +5, +6, +7 (a strongly acidic oxide) |
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Electronegativity | Pauling scale: 2.66 |
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Ionization energies | - 1st: 1008.4 kJ/mol
- 2nd: 1845.9 kJ/mol
- 3rd: 3180 kJ/mol
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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 of iodine |
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Natural occurrence | primordial |
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Crystal structure | base-centered 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 ordering | diamagnetic[3] |
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Molar magnetic susceptibility | −88.7×10−6 cm3/mol (298 K)[4] |
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Bulk modulus | 7.7 GPa |
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CAS Number | 7553-56-2 |
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Discovery and first isolation | Bernard Courtois (1811) |
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Main isotopes |
Decay |
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abundance |
half-life (t1/2) |
mode |
product |
123I |
synth |
13 h |
β+100% |
123Te |
124I |
synth |
4.176 d |
ε |
124Te |
125I |
synth |
59.40 d |
ε |
125Te |
127I |
100% |
stable |
129I |
trace |
1.57×107 y |
β− |
129Xe |
131I |
synth |
8.02070 d |
β−100% |
131Xe |
135I |
synth |
6.57 h |
β− |
135Xe |
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Category: Iodine | references |