Indium
Indium (In) is element 49, a post-transition metal in group 13, period 5, with an atomic mass of 114.818 u. It is a solid at room temperature and melts at 156.6 °C. Its electron configuration is [Kr] 5s² 4d¹⁰ 5p¹.
Indium is a soft, silvery post-transition metal, rare enough that it's almost never mined on its own — nearly all of it is recovered as a byproduct of zinc refining. It's remarkably malleable, has a low melting point, and forms the transparent conductive coating found on nearly every touchscreen and flat-panel display in use today.
- Group · Period
- 13 · 5
- At room temp
- solid
- Melts at
- 429.75 K
- Density
- 7.31 g/cm³
- Discovered
- 1863
Key facts about indium
Quick answers, built from the sourced data in the property tables.
- What is the electron configuration of indium?
- The electron configuration of indium is [Kr] 5s² 4d¹⁰ 5p¹. Written out in full, that is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s² 4d¹⁰ 5p¹.
- What is the density of indium?
- The density of indium is 7.31 g/cm³.
- What are the melting and boiling points of indium?
- Indium melts at 429.75 K (156.6 °C, 313.88 °F) and boils at 2345 K (2071.85 °C, 3761.33 °F).
- What is the electron affinity of indium?
- The electron affinity of indium is 0.3 eV, which is about 28.9 kJ/mol.
- How many stable isotopes does indium have?
- Indium has one stable isotope: In-113 (4.281%).
Uses
Indium’s signature application is indium tin oxide, a transparent, electrically conductive coating applied to the glass or plastic of touchscreens, LCD monitors, and thin-film solar panels — virtually every device with a touch-sensitive or flat-panel display relies on it. Indium’s low melting point and softness also make it useful in specialized solders and fusible alloys, including some low-temperature solders used in electronics and vacuum-sealing applications where a normal solder would be too rigid or melt at too high a temperature.
Beyond electronics, thin indium coatings and foils are used as soft, deformable seals in high-vacuum equipment, since the metal flows into tiny gaps under pressure to create an airtight seal.
History
Indium was discovered in 1863 by German chemists Ferdinand Reich and Hieronymus Theodor Richter while examining a zinc ore sample using a spectroscope, a new tool at the time for identifying elements by the specific colors of light they emit. They spotted a distinctive indigo-blue line in the spectrum that didn’t match any known element, and named the new metal indium after that color. It remained a scientific curiosity with few practical uses for much of the twentieth century, until the rise of flat-panel displays turned indium tin oxide into one of the most commercially important thin-film materials in modern electronics.
Fun facts
- Indium was discovered in 1863 through a bright indigo-blue line in its spectrum, which is where its name comes from.
- Indium tin oxide, a transparent conductor made from indium, coats the screen of nearly every smartphone, tablet and flat-panel display.
- Indium is so soft it can be scratched with a fingernail, and bending a bar of it produces an audible high-pitched cry, similar to tin.
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Frequently asked questions
Why is indium used in touchscreens?
Indium tin oxide has a rare combination of properties: it conducts electricity while still being transparent to visible light. That lets manufacturers print an invisible conductive grid directly onto glass or plastic, which is exactly what a touchscreen or LCD display needs to sense a touch or control pixels without blocking the image underneath.
Is indium a rare element?
It's uncommon in the Earth's crust and doesn't form its own significant ore deposits, so almost all indium is extracted as a byproduct while refining zinc ores. Demand has grown quickly with the rise of touchscreens and flat-panel displays, which is why indium supply and recycling have become an active area of industrial interest.
Why does indium make a crying sound when you bend it?
Like tin, indium metal is made of large crystal grains that shift and twin internally under stress. As a bar of indium is bent, those crystal planes slide past each other in tiny jumps, and each jump releases a small click of sound — together they add up to the faint, high-pitched cry that both metals are known for.
Compounds
5 notable compounds containing In
- InSbsemiconductor
Indium antimonide
A narrow-bandgap III-V semiconductor crystal that responds strongly to infrared light, especially when cooled to cryogenic temperatures.
Used for: Infrared detectors and thermal imaging sensors
- InPsemiconductor
Indium phosphide
A III-V semiconductor with a direct bandgap well suited to generating and carrying light, making it central to modern fiber-optic technology.
Used for: High-speed fiber-optic transceivers and laser diodes
- InCl3halide
Indium(III) chloride
A white, highly hygroscopic solid that acts as a mild Lewis acid catalyst and serves as the usual starting point for making other indium compounds.
Used for: Lewis acid catalyst in organic synthesis
- In2O3oxide
Indium(III) oxide
A pale yellow oxide and indium's main commercial form, valued for the transparent, conductive thin films it forms when doped with a small amount of tin.
Used for: Precursor for transparent conductive coatings on touchscreens and displays
- In2(SO4)3salt
Indium(III) sulfate
A white, water-soluble indium salt used mainly as a bath component for depositing bright indium coatings by electroplating.
Used for: Electrolyte in indium electroplating baths
Isotopes
42 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width | Spin/parity | Magnetic moment | Quadrupole moment |
|---|---|---|---|---|---|---|---|---|---|
| In-113 stable | 4.281% | Stable | — | -89,367.12 keV | 8,522.93 keV | — | 9/2+ | 5.5208 μN | 0.761 b |
| In-115 | 95.719% | 4.41E+14 Y | Beta-minus decay (100%) | -89,536.36 keV | 8,516.55 keV | 3.28 × 10-38 eV | 9/2+ | 5.5326 μN | 0.772 b |
| In-96 | — | — | Proton emission, Electron capture / beta-plus decay, ECP | -38,090 keV | 8,069 keV | — | — | — | — |
| In-97 | — | 36 ms | Beta-plus decay (100%), Beta-plus, proton emission (1.7%) | -47,390 keV | 8,165 keV | 1.27 × 10-14 eV | (9/2+) | — | — |
| In-98 | — | 30 ms | Electron capture / beta-plus decay (100%), ECP (0.13%) | -53,906 keV | 8,230 keV | 1.52 × 10-14 eV | (0+) | — | — |
| In-99 | — | 3.1 s | Beta-plus, proton emission (0.9%) | -61,376 keV | 8,304 keV | 1.47 × 10-16 eV | — | — | — |
| In-100 | — | 5.65 s | Electron capture / beta-plus decay (100%), ECP (1.66%) | -64,178.15 keV | 8,329.75 keV | 8.08 × 10-17 eV | (6+) | — | — |
| In-101 | — | 15.1 s | Electron capture / beta-plus decay (100%), Beta-plus, proton emission | -68,544.9 keV | 8,370.43 keV | 3.02 × 10-17 eV | (9/2+) | — | — |
| In-102 | — | 23.3 s | Electron capture / beta-plus decay (100%), Beta-plus, proton emission (0.0093%) | -70,694.9 keV | 8,388.57 keV | 1.96 × 10-17 eV | (6+) | — | — |
| In-103 | — | 65 s | Electron capture / beta-plus decay (100%) | -74,632.4 keV | 8,423.72 keV | 7.02 × 10-18 eV | (9/2)+ | — | — |
| In-104 | — | 1.80 m | Electron capture / beta-plus decay (100%) | -76,182.68 keV | 8,435.24 keV | 4.22 × 10-18 eV | (6+) | 4.43 μN | 0.63 b |
| In-105 | — | 5.07 m | Electron capture / beta-plus decay (100%) | -79,640.58 keV | 8,464.7 keV | 1.50 × 10-18 eV | 9/2+ | 5.667 μN | 0.79 b |
| In-106 | — | 6.2 m | Electron capture / beta-plus decay (100%) | -80,608.15 keV | 8,470.12 keV | 1.23 × 10-18 eV | 7+ | 4.908 μN | 0.92 b |
| In-107 | — | 32.4 m | Electron capture / beta-plus decay (100%) | -83,566.67 keV | 8,494.04 keV | 2.35 × 10-19 eV | 9/2+ | 5.577 μN | 0.77 b |
| In-108 | — | 58.0 m | Electron capture / beta-plus decay (100%) | -84,119.83 keV | 8,495.25 keV | 1.31 × 10-19 eV | 7+ | 4.554 μN | 0.957 b |
| In-109 | — | 4.159 h | Electron capture / beta-plus decay (100%) | -86,489.53 keV | 8,513.1 keV | 3.05 × 10-20 eV | 9/2+ | 5.53 μN | 0.8 b |
| In-110 | — | 4.92 h | Electron capture / beta-plus decay (100%) | -86,469.97 keV | 8,508.91 keV | 2.58 × 10-20 eV | 7+ | 4.706 μN | 0.32 b |
| In-111 | — | 2.8047 d | Electron capture (100%) | -88,392.05 keV | 8,522.28 keV | 1.88 × 10-21 eV | 9/2+ | — | 0.76 b |
| In-112 | — | 14.88 m | Electron capture / beta-plus decay (62%), Beta-minus decay (38%) | -87,990.13 keV | 8,514.67 keV | 5.11 × 10-19 eV | 1+ | 2.82 μN | 0.082 b |
| In-114 | — | 71.9 s | Beta-minus decay (99.5%), Electron capture / beta-plus decay (0.5%) | -88,569.81 keV | 8,511.97 keV | 6.35 × 10-18 eV | 1+ | 2.813 μN | 0.705 b |
| In-116 | — | 14.10 s | Beta-minus decay (99.977%), Electron capture (0.023%) | -88,249.76 keV | 8,501.62 keV | 3.24 × 10-17 eV | 1+ | 2.7826 μN | 0.11 b |
| In-117 | — | 43.2 m | Beta-minus decay (100%) | -88,943.04 keV | 8,503.87 keV | 1.76 × 10-19 eV | 9/2+ | 5.511 μN | 0.79 b |
| In-118 | — | 5.0 s | Beta-minus decay (100%) | -87,228.18 keV | 8,485.67 keV | 9.12 × 10-17 eV | 1+ | 3.316 μN | — |
| In-119 | — | 2.4 m | Beta-minus decay (100%) | -87,698.66 keV | 8,486.14 keV | 3.17 × 10-18 eV | 9/2+ | 5.507 μN | 0.814 b |
| In-120 | — | 3.08 s | Beta-minus decay (100%) | -85,727.74 keV | 8,466.26 keV | 1.48 × 10-16 eV | 1+ | 3.687 μN | — |
| In-121 | — | 23.1 s | Beta-minus decay (100%) | -85,834.59 keV | 8,463.88 keV | 1.98 × 10-17 eV | 9/2+ | 5.494 μN | 0.776 b |
| In-122 | — | 1.5 s | Beta-minus decay (100%) | -83,571.36 keV | 8,442.11 keV | 3.04 × 10-16 eV | 1+ | — | — |
| In-123 | — | 6.15 s | Beta-minus decay (100%) | -83,429.03 keV | 8,437.94 keV | 7.42 × 10-17 eV | 9/2+ | 5.483 μN | 0.722 b |
| In-124 | — | 3.12 s | Beta-minus decay (100%) | -80,867.78 keV | 8,414.32 keV | 1.46 × 10-16 eV | (1)+ | 3.882 μN | 0.58 b |
| In-125 | — | 2.36 s | Beta-minus decay (100%) | -80,412.31 keV | 8,407.94 keV | 1.93 × 10-16 eV | 9/2+ | 5.494 μN | 0.68 b |
| In-126 | — | 1.53 s | Beta-minus decay (100%) | -77,809.38 keV | 8,384.61 keV | 2.98 × 10-16 eV | 3(+) | 4.055 μN | 0.47 b |
| In-127 | — | 1.09 s | Beta-minus decay (100%), Beta-minus, neutron emission (0.03%) | -76,879.9 keV | 8,374.82 keV | 4.19 × 10-16 eV | (9/2+) | 5.514 μN | 0.56 b |
| In-128 | — | 0.84 s | Beta-minus decay (100%), Beta-minus, neutron emission (0.046%) | -74,190.12 keV | 8,351.44 keV | 5.43 × 10-16 eV | (3)+ | — | — |
| In-129 | — | 611 ms | Beta-minus decay (100%), Beta-minus, neutron emission (0.23%) | -72,834.89 keV | 8,338.76 keV | 7.47 × 10-16 eV | (9/2+) | — | — |
| In-130 | — | 0.29 s | Beta-minus decay (100%), Beta-minus, neutron emission (0.93%) | -69,906.53 keV | 8,314.18 keV | 1.57 × 10-15 eV | 1(-) | — | — |
| In-131 | — | 0.28 s | Beta-minus decay (100%), Beta-minus, neutron emission (2%) | -68,024.37 keV | 8,297.95 keV | 1.63 × 10-15 eV | (9/2+) | — | — |
| In-132 | — | 0.200 s | Beta-minus decay (100%), Beta-minus, neutron emission (7.4%), B-2N | -62,411.55 keV | 8,253.72 keV | 2.28 × 10-15 eV | (7-) | — | — |
| In-133 | — | 165 ms | Beta-minus decay (100%), Beta-minus, neutron emission (85%) | -57,690 keV | 8,217 keV | 2.77 × 10-15 eV | (9/2+) | — | — |
| In-134 | — | 140 ms | Beta-minus decay (100%), Beta-minus, neutron emission (65%) | -51,970 keV | 8,173 keV | 3.26 × 10-15 eV | (4- TO 7-) | — | — |
| In-135 | — | 101 ms | Beta-minus decay (100%), Beta-minus, neutron emission (0%), B-2N | -47,110 keV | 8,136 keV | 4.52 × 10-15 eV | — | — | — |
| In-136 | — | 85 ms | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -40,970 keV | 8,091 keV | 5.37 × 10-15 eV | — | — | — |
| In-137 | — | 65 ms | Beta-minus decay (100%), B-2N, Beta-minus, neutron emission | -35,830 keV | 8,053 keV | 7.02 × 10-15 eV | — | — | — |
Spin/parity describes the nucleus's intrinsic angular momentum and symmetry. Magnetic moment (in nuclear magnetons, μN) and quadrupole moment (in barns, b) describe the shape of the nucleus's charge distribution — a nonzero quadrupole moment means the nucleus isn't perfectly spherical. These are only measured for a subset of isotopes, mostly stable or long-lived ones, so many rows show "—" rather than a value.