Iodine

Iodine (I)

Dark violet nonmetallic element, belongs to group 17 of the periodic table. Insoluble in water. Required as a trace element for living organisms. One stable isotope, I-127 exists, in addition to fourteen radioactive isotopes. Chemically the least reactive of the halogens, and the most electropositive metallic halogen. Discovered in 1812 by Courtois.
Atomic Number53
Atomic Weight126.90447
Mass Number127
Group17
Period5
Blockp
Protons53 p+
Neutrons74 n0
Electrons53 e-
Sample of iodine.jpg Iodine-sample.jpg Iodine powder.JPG Iodine microcrystals.JPG Iodine'.JPG Animated Bohr Model of I (Iodine) Enhanced Bohr Model of I (Iodine) Bohr Model: I (Iodine) Orbital Diagram of I (Iodine)

Properties

Atomic Radius
140 pm
Molar Volume
Covalent Radius
133 pm
Metallic Radius
Ionic Radius
220 pm
Crystal Radius
206 pm
Van der Waals Radius
198 pm
Density
4.933 g/cm³
Energy
Proton Affinity
608.2 kJ/mol
Electron Affinity
3.0590368 eV/particle
Ionization Energy
10.45126 eV/particle
Heat of Vaporization
41.95 kJ/mol
Heat of Fusion
15.52 kJ/mol
Heat of Formation
106.757 kJ/mol
Electrons
Electron Shells2, 8, 18, 18, 7
Valence Electrons7
Electron Configuration[Kr] 4d10 5s2 5p5
Oxidation States-1, 1, 2, 3, 4, 5, 6, 7
Electronegativity
2.66
Electrophilicity
3.0864889135126865 eV/particle
Phases
PhaseSolid
Gas Phase
Boiling Point
457.55 K
Melting Point
386.85 K
Critical Pressure
Critical Temperature
819.15 K
Triple Point
386.75 K
12.11 kPa
Visual
Color
Slate Gray
Appearancelustrous metallic gray, violet as a gas
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
54.43 J/(mol K)
Specific Heat Capacity
0.214 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeInsulator
Electrical Conductivity
0.0000000000001 MS/m
Electrical Resistivity
10,000,000 m Ω
Superconducting Point
Magnetism
Typediamagnetic
Magnetic Susceptibility (Mass)
-0.0000000045 m³/Kg
Magnetic Susceptibility (Molar)
-0.00000000114 m³/mol
Magnetic Susceptibility (Volume)
-0.0000222
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal StructureBase Centered Orthorhombic (ORC)
Lattice Constant
7.72 Å
Lattice Anglesπ/2, π/2, π/2
Mechanical Properties
Hardness
Bulk Modulus
7.7 GPa
Shear Modulus
Young Modulus
Poisson Ratio
Speed of Sound
Classification
CategoryHalogens, Halogens
CAS GroupVIIB
IUPAC GroupVIIA
Glawe Number99
Mendeleev Number109
Pettifor Number97
Geochemical Classsemi-volatile
Goldschmidt Classlitophile
Other
Gas Basicity
583.5 kJ/mol
Dipole Polarizability
32.9 ± 1.3 a₀
C6 Dispersion Coefficient
385 a₀
AllotropesDiiodine
Neutron Cross Section
6.3
Neutron Mass Absorption
0.0018
Quantum Numbers2P3/2
Space Group64 (Cmca)

Isotopes of Iodine

Stable Isotopes1
Unstable Isotopes41
Radioactive Isotopes40

106I

Abundance
Relative Atomic Mass
105.953516 ± 0.000429 Da
Mass Number106
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year
Parity

106I Decay Modes
Decay ModeIntensity
α (α emission)%

107I

AbundanceRadioactive ☢️
Relative Atomic Mass
106.946935 ± 0.000322 Da
Mass Number107
G-Factor
Half Life
Spin5/2
Quadrupole Moment
Discovery Year
Parity+

107I Decay Modes
Decay ModeIntensity
α (α emission)%

108I

AbundanceRadioactive ☢️
Relative Atomic Mass
107.943348 ± 0.000109 Da
Mass Number108
G-Factor
Half Life
26.4 ± 0.8 ms
Spin1
Quadrupole Moment
Discovery Year1991
Parity+

108I Decay Modes
Decay ModeIntensity
α (α emission)99.5%
p (proton emission)0.5%
β+ (β+ decay; β+ = ϵ + e+)%
β+ p (β+-delayed proton emission)%

109I

AbundanceRadioactive ☢️
Relative Atomic Mass
108.938086022 ± 0.000007223 Da
Mass Number109
G-Factor
Half Life
92.8 ± 0.8 us
Spin1/2
Quadrupole Moment
0
Discovery Year1984
Parity+

109I Decay Modes
Decay ModeIntensity
p (proton emission)99.986%
α (α emission)0.014%

110I

AbundanceRadioactive ☢️
Relative Atomic Mass
109.935085102 ± 0.000066494 Da
Mass Number110
G-Factor
Half Life
664 ± 24 ms
Spin1
Quadrupole Moment
Discovery Year1977
Parity+

110I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)83%
α (α emission)17%
β+ p (β+-delayed proton emission)11%
β+α (β+-delayed α emission)1.1%

111I

AbundanceRadioactive ☢️
Relative Atomic Mass
110.930269236 ± 0.000005103 Da
Mass Number111
G-Factor
Half Life
2.5 ± 0.2 s
Spin5/2
Quadrupole Moment
Discovery Year1977
Parity+

111I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
α (α emission)0.088%
β+ p (β+-delayed proton emission)%

112I

AbundanceRadioactive ☢️
Relative Atomic Mass
111.928004548 ± 0.000011 Da
Mass Number112
G-Factor
Half Life
3.34 ± 0.08 s
Spin1
Quadrupole Moment
Discovery Year1977
Parity+

112I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
α (α emission)0.0012%
β+ p (β+-delayed proton emission)0.88%
β+α (β+-delayed α emission)0.104%

113I

AbundanceRadioactive ☢️
Relative Atomic Mass
112.923650062 ± 0.0000086 Da
Mass Number113
G-Factor
Half Life
6.6 ± 0.2 s
Spin5/2
Quadrupole Moment
Discovery Year1977
Parity+

113I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
α (α emission)3.31%
β+α (β+-delayed α emission)%

114I

AbundanceRadioactive ☢️
Relative Atomic Mass
113.9220189 ± 0.0000215 Da
Mass Number114
G-Factor
Half Life
2.01 ± 0.15 s
Spin1
Quadrupole Moment
Discovery Year1977
Parity+

114I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%
α (α emission)7.7%

115I

AbundanceRadioactive ☢️
Relative Atomic Mass
114.918048 ± 0.000031 Da
Mass Number115
G-Factor
Half Life
1.3 ± 0.2 m
Spin5/2
Quadrupole Moment
Discovery Year1969
Parity+

115I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

116I

AbundanceRadioactive ☢️
Relative Atomic Mass
115.916885513 ± 0.000080555 Da
Mass Number116
G-Factor
Half Life
2.91 ± 0.15 s
Spin1
Quadrupole Moment
Discovery Year1976
Parity+

116I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

117I

AbundanceRadioactive ☢️
Relative Atomic Mass
116.913645649 ± 0.000027437 Da
Mass Number117
G-Factor
1.24 ± 0.08
Half Life
2.22 ± 0.04 m
Spin5/2
Quadrupole Moment
Discovery Year1969
Parity

117I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
e+ (positron emission)77%

118I

AbundanceRadioactive ☢️
Relative Atomic Mass
117.913074 ± 0.000021213 Da
Mass Number118
G-Factor
1 ± 0.1
Half Life
13.7 ± 0.5 m
Spin2
Quadrupole Moment
Discovery Year1957
Parity-

118I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

119I

AbundanceRadioactive ☢️
Relative Atomic Mass
118.91006091 ± 0.000023302 Da
Mass Number119
G-Factor
1.16 ± 0.04
Half Life
19.1 ± 0.4 m
Spin5/2
Quadrupole Moment
Discovery Year1954
Parity+

119I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
e+ (positron emission)51%
ϵ (electron capture)49%

120I

AbundanceRadioactive ☢️
Relative Atomic Mass
119.910093729 ± 0.000016212 Da
Mass Number120
G-Factor
0.615 ± 0.015
Half Life
81.67 ± 0.18 m
Spin2
Quadrupole Moment
Discovery Year1957
Parity-

120I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

121I

AbundanceRadioactive ☢️
Relative Atomic Mass
120.907411492 ± 0.00000507 Da
Mass Number121
G-Factor
0.92 ± 0.04
Half Life
2.12 ± 0.01 h
Spin5/2
Quadrupole Moment
Discovery Year1950
Parity+

121I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

122I

AbundanceRadioactive ☢️
Relative Atomic Mass
121.907590094 ± 0.000005561 Da
Mass Number122
G-Factor
0.94 ± 0.03
Half Life
3.63 ± 0.06 m
Spin1
Quadrupole Moment
Discovery Year1950
Parity+

122I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
e+ (positron emission)78%
ϵ (electron capture)22%

123I

AbundanceRadioactive ☢️
Relative Atomic Mass
122.905589753 ± 0.000003956 Da
Mass Number123
G-Factor
1.1272 ± 0.0028
Half Life
13.2232 ± 0.0015 h
Spin5/2
Quadrupole Moment
Discovery Year1949
Parity+

123I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

124I

AbundanceRadioactive ☢️
Relative Atomic Mass
123.906210297 ± 0.000002467 Da
Mass Number124
G-Factor
0.723 ± 0.002
Half Life
4.176 ± 0.0003 d
Spin2
Quadrupole Moment
Discovery Year1938
Parity-

124I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

125I

AbundanceRadioactive ☢️
Relative Atomic Mass
124.90463061 ± 0.000001452 Da
Mass Number125
G-Factor
1.1284 ± 0.002
Half Life
59.392 ± 0.008 d
Spin5/2
Quadrupole Moment
-0.752 ± 0.017
Discovery Year1947
Parity+

125I Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

126I

AbundanceRadioactive ☢️
Relative Atomic Mass
125.905624205 ± 0.000004055 Da
Mass Number126
G-Factor
0.719 ± 0.002
Half Life
12.93 ± 0.05 d
Spin2
Quadrupole Moment
Discovery Year1938
Parity-

126I Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)52.7%
β (β decay)47.3%

127I

Abundance
100
Relative Atomic Mass
126.904472592 ± 0.000003887 Da
Mass Number127
G-Factor
Half Life
Spin5/2
Quadrupole Moment
-0.688 ± 0.01
Discovery Year1920
Parity+

128I

AbundanceRadioactive ☢️
Relative Atomic Mass
127.905809355 ± 0.000003887 Da
Mass Number128
G-Factor
Half Life
24.99 ± 0.02 m
Spin1
Quadrupole Moment
Discovery Year1934
Parity+

128I Decay Modes
Decay ModeIntensity
β (β decay)93.1%
β+ (β+ decay; β+ = ϵ + e+)6.9%

129I

AbundanceRadioactive ☢️
Relative Atomic Mass
128.904983643 ± 0.000003385 Da
Mass Number129
G-Factor
Half Life
16.14 ± 0.12 My
Spin7/2
Quadrupole Moment
Discovery Year1951
Parity+

129I Decay Modes
Decay ModeIntensity
β (β decay)100%

130I

AbundanceRadioactive ☢️
Relative Atomic Mass
129.906670168 ± 0.000003385 Da
Mass Number130
G-Factor
0.6698 ± 0.0014
Half Life
12.36 ± 0.01 h
Spin5
Quadrupole Moment
Discovery Year1938
Parity+

130I Decay Modes
Decay ModeIntensity
β (β decay)100%

131I

AbundanceRadioactive ☢️
Relative Atomic Mass
130.906126375 ± 0.000000649 Da
Mass Number131
G-Factor
0.78228571428571 ± 0.00028571428571429
Half Life
8.0249 ± 0.0006 d
Spin7/2
Quadrupole Moment
-0.34 ± 0.02
Discovery Year1939
Parity+

131I Decay Modes
Decay ModeIntensity
β (β decay)100%

132I

AbundanceRadioactive ☢️
Relative Atomic Mass
131.907993511 ± 0.000004364 Da
Mass Number132
G-Factor
0.772 ± 0.00175
Half Life
2.295 ± 0.013 h
Spin4
Quadrupole Moment
0.08 ± 0.01
Discovery Year1948
Parity+

132I Decay Modes
Decay ModeIntensity
β (β decay)100%

133I

AbundanceRadioactive ☢️
Relative Atomic Mass
132.9078284 ± 0.000006335 Da
Mass Number133
G-Factor
0.816 ± 0.0014285714285714
Half Life
20.83 ± 0.08 h
Spin7/2
Quadrupole Moment
-0.23 ± 0.01
Discovery Year1940
Parity+

133I Decay Modes
Decay ModeIntensity
β (β decay)100%

134I

AbundanceRadioactive ☢️
Relative Atomic Mass
133.90977566 ± 0.000005213 Da
Mass Number134
G-Factor
Half Life
52.5 ± 0.2 m
Spin4
Quadrupole Moment
Discovery Year1948
Parity

134I Decay Modes
Decay ModeIntensity
β (β decay)100%

135I

AbundanceRadioactive ☢️
Relative Atomic Mass
134.910059355 ± 0.000002211 Da
Mass Number135
G-Factor
0.84 ± 0.00057142857142857
Half Life
6.58 ± 0.03 h
Spin7/2
Quadrupole Moment
Discovery Year1940
Parity+

135I Decay Modes
Decay ModeIntensity
β (β decay)100%

136I

AbundanceRadioactive ☢️
Relative Atomic Mass
135.914604693 ± 0.000015231 Da
Mass Number136
G-Factor
Half Life
83.4 ± 0.4 s
Spin1
Quadrupole Moment
Discovery Year1949
Parity-

136I Decay Modes
Decay ModeIntensity
β (β decay)100%

137I

AbundanceRadioactive ☢️
Relative Atomic Mass
136.918028178 ± 0.000009 Da
Mass Number137
G-Factor
Half Life
24.13 ± 0.12 s
Spin7/2
Quadrupole Moment
Discovery Year1943
Parity+

137I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)7.51%

138I

AbundanceRadioactive ☢️
Relative Atomic Mass
137.922726392 ± 0.0000064 Da
Mass Number138
G-Factor
Half Life
6.26 ± 0.03 s
Spin1
Quadrupole Moment
Discovery Year1949
Parity-

138I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)5.33%

139I

AbundanceRadioactive ☢️
Relative Atomic Mass
138.9264934 ± 0.0000043 Da
Mass Number139
G-Factor
Half Life
2.28 ± 0.011 s
Spin7/2
Quadrupole Moment
Discovery Year1949
Parity+

139I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)9.74%

140I

AbundanceRadioactive ☢️
Relative Atomic Mass
139.931715914 ± 0.000013 Da
Mass Number140
G-Factor
Half Life
588 ± 10 ms
Spin2
Quadrupole Moment
Discovery Year1972
Parity-

140I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)7.6%
2n (2-neutron emission)%

141I

AbundanceRadioactive ☢️
Relative Atomic Mass
140.935666081 ± 0.000017 Da
Mass Number141
G-Factor
Half Life
420 ± 7 ms
Spin7/2
Quadrupole Moment
Discovery Year1974
Parity+

141I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)21.2%

142I

AbundanceRadioactive ☢️
Relative Atomic Mass
141.941166595 ± 0.0000053 Da
Mass Number142
G-Factor
Half Life
235 ± 11 ms
Spin2
Quadrupole Moment
Discovery Year1975
Parity-

142I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

143I

AbundanceRadioactive ☢️
Relative Atomic Mass
142.945475 ± 0.000215 Da
Mass Number143
G-Factor
Half Life
182 ± 8 ms
Spin7/2
Quadrupole Moment
Discovery Year1994
Parity+

143I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

144I

AbundanceRadioactive ☢️
Relative Atomic Mass
143.951336 ± 0.000429 Da
Mass Number144
G-Factor
Half Life
94 ± 8 ms
Spin1
Quadrupole Moment
Discovery Year1994
Parity-

144I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

145I

AbundanceRadioactive ☢️
Relative Atomic Mass
144.955845 ± 0.000537 Da
Mass Number145
G-Factor
Half Life
89.7 ± 9.3 ms
Spin7/2
Quadrupole Moment
Discovery Year2010
Parity+

145I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

146I

AbundanceRadioactive ☢️
Relative Atomic Mass
145.961846 ± 0.000322 Da
Mass Number146
G-Factor
Half Life
94 ± 26 ms
Spin
Quadrupole Moment
Discovery Year2018
Parity

146I Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

147I

AbundanceRadioactive ☢️
Relative Atomic Mass
146.966505 ± 0.000322 Da
Mass Number147
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2018
Parity-

147I Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

History

Iodine was discovered by French chemist Bernard Courtois in 1811. He treated the liquor obtained from the extraction of kelp, with sulfuric acid to produce a vapour with a violet color. In 1812, Joseph Louis Gay-Lussac demonstrated that iodine was an element and its chemical relationship to chlorine. From the Greek word iodes, violet

DiscoverersBernard Courtois
Discovery LocationFrance
Discovery Year1811
Etymology (Name Origin)Greek: iôeides (violet colored).
PronunciationEYE-eh-dine (English)
Elemental iodine is toxic if taken orally
Kelp was the main source of natural iodine in the 18th and 19th centuries

Uses

Iodine compounds are important in organic chemistry and very useful in medicine. A solution containing potassium iodide and iodine in alcohol is used to disinfect external wounds. Silver iodide is a major ingredient to traditional photographic film. Iodine is added to table salt to prevent thyroid disease. Required in small amounts by humans. Once used as an antiseptic, but no longer due to its poisonous nature.

Sources

Occurs on land and in the sea in sodium and potassium compounds.

Abundance
Abundance in Earth's crust
0.45 mg/kg
Abundance in Oceans
0.06 mg/L
Abundance in Human Body
0.00002 %
Abundance in Meteor
0.000025 %
Abundance in Sun
Abundance in Universe
0.0000001 %

Nuclear Screening Constants

1s1.0609
2p4.1526
2s13.933
3d14.0993
3p18.1586
3s18.2126
4d32.066
4p28.9704
4s27.7028
5p41.3885
5s39.5965