Iodine

Chemical, physical and material properties and data of the chemical element Iodine.

Contents

General Information about Iodine

Regular nameIodineChemical symbolIOther namesHistorical namesName meaning, originDiscovery (year)OccurencePosition in the PSEGroup membership

Atomar Properties of Iodine

Atomic number Z53 = number of protonsStandard Atomic Weight126.90447 (3)

Electron configuration of Iodine

1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f	6s	6p	6d	6f	7s	7p
2	2	6	2	6	10	2	6	10		2	5

Shorthand electron configuration of Iodine: [Kr] 4d¹⁰ 5s² 5p⁵ .

Ionization Energies of Iodine

The following table lists the ionization energies IE (ionization potentials); the IE is the energy required in electron volt (eV) per atom to separate a given electron from an Iodine atom.

IE1	IE2	IE3
10.45126	19.1313	33

Isotopic Data of Iodine

An overview of the nuclides as well as the isotopic data and properties are listed on the following page: Iodine isotopes.

Chemistry of Iodine

Oxidation states-1. +1. +3. +5. +7Electronegativity2.5 (Pauling original)
2.66 (Pauling)
2.359 (Allen)
2.7 (Mulliken)
2.50 (Sanderson)
2.21 (Allred-Rochow)
3.5836 eV (Gosh Gupta)
6.76 eV (Pearson)Electron affinity3.059 052(38) eV
295.154(4) kJ mol^-1

Standard Electrode Potential

E⁰ (V)	Symbol	N_ox	Name Ox. Name Red.	Ox. Red.	e^-
0.5355	I	0 - I	Iodine Iodide anion	I₂ (s) ⇄ 2 I^-	+ 2 e^-
0.536	I	0/-I - I	Triiodide anion Iodide anion	I₃^- ⇄ 3 I^-	+ 2 e^-
1.13	I	+ V + I	Iodate anion Hypoiodous acid	[IO₃]^- + 5 H⁺ ⇄ HIO (aq) + 2 H₂O	+ 4 e^-
1.2	I	+ V 0	Iodate anion Iodine	IO₃^- + 12 H⁺ ⇄ 2 I₂ (s) + 6 H₂O	+ 10 e^-
1.44	I	+ I 0	Hypoiodous acid Iodine	2 HIO (aq) + 2 H⁺ ⇄ I₂ (aq) + 2 H₂O	+ 2 e^-

Material and Physical Properties

Melting point113.7 °CEnthalpy of fusion (molar)15.52 kJ mol^-1Boiling point184.4 °CEnthalpy of vaporization41.67 kJ mol^-1Density4.933 g cm^-3

External Data, Identifiers

CAS registry number7553-56-2InChI =1S/IInChIKeyPNDPGZBMCMUPRI-UHFFFAOYSA-NPubChem ID807

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Last update: 2022-12-29

Perma link: https://www.chemlin.org/chemical-elements/iodine.php