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In 49

Indium (In)

post-transition-metal
Period: 5 Group: 13 Block: p

Solid

Standard Atomic Weight

114.818 u

Electron configuration

[Kr] 5s2 4d10 5p1

Melting point

156.6 °C (429.75 K)

Boiling point

2071.85 °C (2345 K)

Density

7310 kg/m³

Oxidation states

−5, −2, −1, 0, +1, +2, +3

Electronegativity (Pauling)

1.78

Ionization energy (1st)

Discovery year

1863

Atomic radius

155 pm

Details

Name origin Latin: indicum (color indigo), the color it shows in a spectroscope.
Discovery country Germany
Discoverers Ferdinand Reich, T. Richter

Indium is a soft, silvery post-transition metal in group 13. It is chemically related to gallium and thallium, but its stable chemistry is dominated by the +3 oxidation state, with +1 compounds also known. The element is rare in Earth's crust and is obtained chiefly as a by-product of zinc refining. Its technological importance is disproportionate to its abundance, especially because transparent conducting indium tin oxide is central to flat-panel displays, touch screens, and other optoelectronic devices.

Indium is available in ultra pure form. Indium is a very soft, silvery-white metal with a brilliant luster. The pure metal gives a high-pitched "cry" when bent. It wets glass, as does gallium.

The name derives from the term "indigo" for the indigo-blue line in the element's spark spectrum. It was discovered in 1863 by the German physicist Ferdinand Reich and the German metallurgist Hieronymus Theodor Richter, while examining zinc blende. They isolated indium in 1867.

Indium was discovered by the German chemists Ferdinand Reich and Hieronymus Theodor Richter in 1863. Reich and Richter had been looking for traces of the element thallium in samples of zinc ores. A brilliant indigo line in the sample's spectrum revealed the existence of indium. Indium is about as abundant as silver but is much easier to recover since it typically occurs along with zinc, iron, lead and copper ores.

From the brilliant indigo line in its spectrum. Discovered by Reich and Richter, who later isolated the metal. Until 1924, a gram or so constituted the world's supply of this element in isolated form. It is probably about as abundant as silver. About 4 million troy ounces of indium are now produced annually in the Free World. Canada is presently producing more than 1,000,000 troy ounces annually.

Read about Indium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 155 pm
Covalent radius 142 pm
Van der Waals radius 193 pm
Metallic radius 142 pm
Density
Molar volume 0.0157 L/mol
Phase at STP solid
Melting point 156.6 °C
Boiling point 2071.85 °C
Thermal conductivity 81.8 W/(m·K)
Specific heat capacity 0.233 J/(g·K)
Molar heat capacity 26.74 J/(mol·K)
Crystal structure tetragonal

Chemical

Electronegativity (Pauling) 1.78
Electronegativity (Allen) 1.656
Electron affinity
Ionization energy (1st)
Ionization energy (2nd)
Ionization energy (3rd)
Ionization energy (4th)
Ionization energy (5th)
Oxidation states −5, −2, −1, 0, +1, +2, +3
Valence electrons 3
Electron configuration
Electron configuration (semantic)

Thermodynamic

Triple point (temperature) 156.5936 °C
Heat of fusion 0.03378764 eV
Heat of vaporization 2.402446 eV
Heat of sublimation 2.518526 eV
Heat of atomization 2.518526 eV
Atomization enthalpy

Nuclear

Stable isotopes 1
Discovery year 1863

Abundance

Abundance (Earth's crust) 0.25 mg/kg
Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 459 pm

Electronic Structure

Electrons per shell 2, 8, 18, 18, 3

Identifiers

CAS number 7440-74-6
Term symbol
InChI InChI=1S/In
InChI Key APFVFJFRJDLVQX-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge
Protons 49
Electrons 49
Charge Neutral
Configuration In: 4d¹⁰ 5s² 5p¹
Electron configuration
Measured
[Kr] 4d¹⁰ 5s² 5p¹
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p¹
Orbital diagram
1s
2/2
2s
2/2
2p
6/6
3s
2/2
3p
6/6
4s
2/2
3d
10/10
4p
6/6
5s
2/2
4d
10/10
5p
1/6 1↑
Total electrons: 49 Unpaired: 1 ?

Atomic model

Protons 49
Neutrons 64
Electrons 49
Mass number 113
Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

25 / 50 (50 with intensity)
Measured
Emission Visible: 380–750 nm
Source: NIST Atomic Spectra Database Wavelengths in air

Isotope Distribution

1134.2900%Mass numberNatural abundance (%)
Mass numberAtomic mass (u)Natural abundanceHalf-life
113 Stable112.90406184 ± 0.000000914.2900%Stable
Measured

Phase / State

1 atm / 101.325 kPa
Solid 25 °C (298.15 K)

Reason: 131.6 °C below melting point (156.6 °C)

Melting point 156.6 °C
Boiling point 2071.85 °C
Below melting by 131.6 °C
0 K Current temperature: 25 °C 6000 K
Phase timeline

Schematic, not to scale

Solid
Liquid
Gas
Melting
Boiling
25°C
Solid
Liquid
Gas
Current

Phase transition points

Melting point Literature
156.6 °C
Boiling point Literature
2071.85 °C
Current phase Calculated
Solid

Transition energies

Heat of fusion Literature
0.03378764 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature
2.402446 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature
2.518526 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature
7310 kg/m³

At standard conditions

Current density Calculated
7310 kg/m³

At standard conditions

Advanced

Triple point Literature
156.5936 °C

Atomic Spectra

Showing 10 of 49 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

IonChargeTotal linesTransition probabilitiesLevel designations
In I 0922791
In II +1899528899
In III +25500
In IV +34200
In V +43800
NIST Lines Holdings →

Levels Holdings ?

IonChargeLevels
In I 0114
In II +1195
In III +228
In IV +318
In V +442
In VI +52
In VII +62
In VIII +72
In IX +82
In X +92
NIST Levels Holdings →
49 In 114.818

Indium — Atomic Orbital Visualizer

[Kr]5s24d105p1
Energy levels 2 8 18 18 3
Oxidation states -5, -2, -1, 0, +1, +2, +3
HOMO 5p n=5 · l=1 · m=-1
Indium — Atomic Orbital Visualizer Preview
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49 In 114.818

Indium — Crystal Structure Visualizer

Crystal structure data not available

Crystal structure: tetragonal

Ionic Radii

ChargeCoordinationSpinRadius
+34N/A62 pm
+36N/A80 pm
+38N/A92 pm

Compounds

In
114.818 u
In+3
114.818 u
In
112.904 u
In
110.905 u
In
113.905 u
In
114.904 u
In
115.905 u
In
108.907 u
In
118.906 u
In
111.906 u
In
116.905 u
In
109.907 u
In+3
110.905 u
In+
114.818 u
In+3
112.904 u

Isotopes (1)

Mass numberAtomic mass (u)Natural abundanceHalf-lifeDecay mode
113 Stable112.90406184 ± 0.000000914.2900% ± 0.0500%Stable
stable
113 Stable
Atomic mass (u) 112.90406184 ± 0.00000091
Natural abundance 4.2900% ± 0.0500%
Half-life Stable
Decay mode
stable

Spectral Lines

Showing 50 of 277 Spectral Lines. Only spectral lines with measured intensity are shown by default.

Wavelength (nm)IntensityIon stageTypeTransitionAccuracySource
383.46308 nm32000In IIemission5s.5d 1D → 5s.4f 1F*MeasuredNIST
451.12972 nm18000In Iemission5s2.5p 2P* → 5s2.6s 2SMeasuredNIST
410.17504 nm17000In Iemission5s2.5p 2P* → 5s2.6s 2SMeasuredNIST
468.1115 nm16000In IIemission5s.5d 3D → 5s.4f 3F*MeasuredNIST
590.33916 nm9000In IIemission5s.6p 3P* → 5s.6d 3DMeasuredNIST
463.8162 nm8800In IIemission5s.5d 3D → 5s.4f 3F*MeasuredNIST
465.562 nm7800In IIemission5s.5d 3D → 5s.4f 3F*MeasuredNIST
464.4572 nm5900In IIemission5s.5d 3D → 5s.4f 1F*MeasuredNIST
718.29048 nm5800In IIemission5s.6s 3S → 5s.6p 3P*MeasuredNIST
384.2918 nm5600In IIemission5s.5d 1D → 5s.4f 3F*MeasuredNIST
591.87693 nm5100In IIemission5s.6p 1P* → 5s.6d 1DMeasuredNIST
616.254 nm4100In IIemission5s.4f 1F* → 5s<1/2,F=4>.6gMeasuredNIST
689.15826 nm3900In IIemission5s.6s 3S → 5s.6p 3P*MeasuredNIST
585.31709 nm3400In IIemission5s.6p 3P* → 5s.6d 3DMeasuredNIST
609.59333 nm3300In IIemission5s.6p 3P* → 5s.6d 3DMeasuredNIST
468.4791 nm2500In IIemission5s.5d 3D → 5s.4f 3F*MeasuredNIST
727.66388 nm2400In IIemission5s.6s 3S → 5s.6p 3P*MeasuredNIST
614.953 nm2200In IIemission5s.4f 3F* → 5s<1/2,F=4>.6gMeasuredNIST
613.986 nm2100In IIemission5s.4f 3F* → 5s<1/2,F=5>.6gMeasuredNIST
614.32 nm2100In IIemission5s.4f 3F* → 5s<1/2,F=4>.6gMeasuredNIST
614.813 nm2100In IIemission5s.4f 3F* → 5s<1/2,F=5>.6gMeasuredNIST
616.113 nm2000In IIemission5s.4f 1F* → 5s<1/2,F=5>.6gMeasuredNIST
465.6736 nm1700In IIemission5s.5d 3D → 5s.4f 3F*MeasuredNIST
551.3006 nm1500In IIemission5p2 3P → 5s.4f 1F*MeasuredNIST
614.126 nm1500In IIemission5s.4f 3F* → 5s<1/2,F=4>.6gMeasuredNIST
405.69377 nm1300In IIemission5s.6p 3P* → 5s.8s 3SMeasuredNIST
591.52626 nm1300In IIemission5s.6p 3P* → 5s.6d 3DMeasuredNIST
557.6866 nm1200In IIemission5s.7p 1P* → 5s.10d 1DMeasuredNIST
551.935 nm1100In IIemission5s.6d 3D → 5s.7f 3F*MeasuredNIST
549.7486 nm1000In IIemission5s.6d 3D → 5s.7f 3F*MeasuredNIST
550.7048 nm1000In IIemission5s.6d 3D → 5s.7f 3F*MeasuredNIST
551.0883 nm1000In IIemission5s.7p 3P* → 5s.10d 3DMeasuredNIST
512.0847 nm960In IIemission5s.4f 3F* → 5s<1/2,F=5>.7gMeasuredNIST
390.20794 nm910In IIemission5s.6p 1P* → 5s.7d 1DMeasuredNIST
384.2158 nm900In IIemission5s.5d 1D → 5s.4f 3F*MeasuredNIST
512.1781 nm880In IIemission5s.4f 3F* → 5s<1/2,F=4>.7gMeasuredNIST
611.58707 nm830In IIemission5s.6p 3P* → 5s.6d 3DMeasuredNIST
511.7388 nm810In IIemission5s.4f 3F* → 5s<1/2,F=4>.7gMeasuredNIST
511.5109 nm800In IIemission5s.4f 3F* → 5s<1/2,F=5>.7gMeasuredNIST
512.9865 nm710In IIemission5s.4f 1F* → 5s<1/2,F=5>.7gMeasuredNIST
463.7055 nm610In IIemission5s.5d 3D → 5s.4f 3F*MeasuredNIST
511.6041 nm590In IIemission5s.4f 3F* → 5s<1/2,F=4>.7gMeasuredNIST
550.7779 nm570In IIemission5s.6d 3D → 5s.7f 3F*MeasuredNIST
414.9635 nm550In IIemission5s.4f 1F* → 5s<1/2,F=5>.10gMeasuredNIST
530.94926 nm550In IIemission5s.6p 3P* → 5s.6d 1DMeasuredNIST
454.8998 nm540In IIemission5p2 1D → 5s.8p 3P*MeasuredNIST
461.6069 nm540In IIemission5s.4f 3F* → 5s<1/2,F=4>.8gMeasuredNIST
457.0881 nm520In IIemission5s.6d 3D → 5s.9f 3F*MeasuredNIST
458.701 nm520In IIemission5s.6d 3D → 5s.9f 3F*MeasuredNIST
457.1286 nm510In IIemission5s.6d 3D → 5s.9f 3F*MeasuredNIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)  
Covalent radius (Pyykkö, double)  
Covalent radius (Pyykkö, triple)  

Van der Waals Radii

Bondi  
Batsanov  
Alvarez  
UFF  
MM3  
Dreiding  

Atomic & Metallic Radii

Atomic radius (Rahm)  
Metallic radius (C12)  

Numbering Scales

Mendeleev
Pettifor
Glawe

Electronegativity Scales

Ghosh
Miedema
Gunnarsson–Lundqvist
Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability  
Dipole polarizability (unc.)  
C₆  
C₆ (Gould–Bučko)  

Miedema Parameters

Miedema molar volume  
Miedema electron density

Supply Risk & Economics

Production concentration
Relative supply risk
Political stability (top producer)

Phase Transitions & Allotropes

Melting point429.75 K
Boiling point2300.15 K
Triple point (temperature)429.74 K

Oxidation State Categories

+2 extended
0 extended
−5 extended
−2 extended
+1 extended
−1 extended
+3 main

Advanced Reference Data

Screening Constants (11)
nOrbitalσ
1s0.9903
2p4.102
2s12.8764
3d14.3218
3p17.4793
3s17.3692
4d32.0584
4p28.6312
4s27.2388
5p40.53
Crystal Radii Detail (3)
ChargeCNSpinrcrystal (pm)Origin
3IV76
3VI94from r^3 vs V plots,
3VIII106from r^3 vs V plots, calculated,
Isotope Decay Modes (69)
IsotopeModeIntensity
96B+—
96p—
97B+100%
97B+p2.3%
97p—
98B+100%
98B+p0.1%
99B+100%
99B+p0.3%
100B+100%
X‑ray Scattering Factors (510)
Energy (eV)f₁f₂
10—2.16244
10.1617—2.07002
10.3261—1.98155
10.4931—1.89686
10.6628—1.81579
10.8353—1.72844
11.0106—1.54985
11.1886—1.35731
11.3696—0.99325
11.5535—0.74202

Additional Data

Sources

Sources of this element.

Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained; however, it is also found in iron, lead, and copper ores.

References (1)

References

(9)
2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)
In

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)
Indium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

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License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.
5 Jefferson Lab, U.S. Department of Energy
Indium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html
6 Los Alamos National Laboratory, U.S. Department of Energy
Indium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory
Indium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements
Indium

This section provides all form of data related to element Indium.

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9 PubChem Elements
Indium

The element property data was retrieved from publications.

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Last updated:

Data verified:

Content is reviewed against latest scientific data.