Indium (In) is a rare, lustrous, silvery-white metallic chemical element . German chemists Ferdinand Reich and Hieronymus Theodor Richter discovered it in 1863 while examining zinc ore samples. The element's name comes from a predominant indigo spectral line. Indium is softer than lead and very pliable, and emits a high-pitched “cry” when bent, similar to tin. The Earth’s crust contains about 0.05 part per million of indium by weight. Indium is useful for creating hermetic seals between glass, metals, quartz, ceramics, and marble because, when molten, it clings to clean glass and other surfaces. It is also used to coat aircraft engine bearings to improve corrosion resistance and help the surface retain a more adherent oil film. The metal is also employed in the manufacture of semiconductor devices and for soldering parts of germanium transistors and rectifiers.

Where is indium found on the periodic table?

Indium (In), a rare, silvery-white metal, is a chemical element in main Group 13 (IIIa, or boron group) of the periodic table . It was discovered in 1863 by German chemists Ferdinand Reich and Hieronymus Theodor Richter while examining zinc ore samples. Indium has the atomic number 49 and an atomic weight of 114.82.

What are some important physical properties of indium?

Indium (In) is a rare, silvery-white metallic chemical element that is softer than lead and very pliable. When bent, pure indium emits a high-pitched “cry,” similar to tin. Its melting point is 156.61 °C (313.89 °F), and its boiling point is 2,080 °C (3,776 °F). Indium has a specific gravity of 7.31 at 20 °C (68 °F). Indium is not affected by air at room temperature. At high heat, it burns with a blue-violet flame, forming In₂O₃, a yellow oxide. Indium is amphoteric , dissolving in acids and concentrated alkalies.

How is indium commonly used in everyday technology?

Indium, a rare, silvery-white metal, is valued for its unique properties in various technological applications. It is used to create hermetic seals between materials like glass and ceramics. Indium enhances corrosion resistance in aircraft engine bearings and is a component in low-melting alloys found in sprinkler heads and fire-door links. The metal is also employed in semiconductor devices and for soldering parts in germanium transistors and rectifiers. Additionally, indium compounds, such as indium nitride, are used in high-speed field-effect transistors and LEDs for displays.

Why is recycling indium important for technology and the environment?

Indium is a rare, silvery-white metal primarily sourced as a byproduct of zinc and lead refining. It is used to create hermetic seals between materials like glass and ceramics, and it's a key component in semiconductor devices, germanium transistors, and rectifiers. Indium compounds, like indium nitride nanorods, are also used in LEDs for TVs and computer displays. Recycling indium is important to conserve this scarce resource and reduce the environmental impact from mining and processing zinc and lead ores.

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indium

chemical element

Also known as: In

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What is indium?
Indium (In) is a rare, lustrous, silvery-white metallic chemical element. German chemists Ferdinand Reich and Hieronymus Theodor Richter discovered it in 1863 while examining zinc ore samples. The element's name comes from a predominant indigo spectral line. Indium is softer than lead and very pliable, and emits a high-pitched “cry” when bent, similar to tin. The Earth’s crust contains about 0.05 part per million of indium by weight.

Indium is useful for creating hermetic seals between glass, metals, quartz, ceramics, and marble because, when molten, it clings to clean glass and other surfaces. It is also used to coat aircraft engine bearings to improve corrosion resistance and help the surface retain a more adherent oil film. The metal is also employed in the manufacture of semiconductor devices and for soldering parts of germanium transistors and rectifiers.
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Where is indium found on the periodic table?
Indium (In), a rare, silvery-white metal, is a chemical element in main Group 13 (IIIa, or boron group) of the periodic table. It was discovered in 1863 by German chemists Ferdinand Reich and Hieronymus Theodor Richter while examining zinc ore samples. Indium has the atomic number 49 and an atomic weight of 114.82.
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1. indium
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What are some important physical properties of indium?
Indium (In) is a rare, silvery-white metallic chemical element that is softer than lead and very pliable. When bent, pure indium emits a high-pitched “cry,” similar to tin.

Its melting point is 156.61 °C (313.89 °F), and its boiling point is 2,080 °C (3,776 °F). Indium has a specific gravity of 7.31 at 20 °C (68 °F).

Indium is not affected by air at room temperature. At high heat, it burns with a blue-violet flame, forming In₂O₃, a yellow oxide. Indium is amphoteric, dissolving in acids and concentrated alkalies.
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1. indium
2. Definition of indium
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How is indium commonly used in everyday technology?
Indium, a rare, silvery-white metal, is valued for its unique properties in various technological applications. It is used to create hermetic seals between materials like glass and ceramics. Indium enhances corrosion resistance in aircraft engine bearings and is a component in low-melting alloys found in sprinkler heads and fire-door links. The metal is also employed in semiconductor devices and for soldering parts in germanium transistors and rectifiers. Additionally, indium compounds, such as indium nitride, are used in high-speed field-effect transistors and LEDs for displays.
2 Britannica Sources
1. indium
2. Definition of indium
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Why is recycling indium important for technology and the environment?
Indium is a rare, silvery-white metal primarily sourced as a byproduct of zinc and lead refining. It is used to create hermetic seals between materials like glass and ceramics, and it's a key component in semiconductor devices, germanium transistors, and rectifiers. Indium compounds, like indium nitride nanorods, are also used in LEDs for TVs and computer displays. Recycling indium is important to conserve this scarce resource and reduce the environmental impact from mining and processing zinc and lead ores.
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1. indium
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indium (In), chemical element, rare metal of main Group 13 (IIIa, or boron group) of the periodic table. Indium has a brilliant silvery-white luster. It was discovered (1863) by German chemists Ferdinand Reich and Hieronymus Theodor Richter while they were examining zinc ore samples. The presence of a predominant indigo spectral line suggested the name. Indium is softer than lead and quite plastic. It can be scratched with a fingernail and can undergo almost limitless deformation. Like tin, the pure metal emits a high-pitched “cry” when bent. Indium is about as rare as silver. Earth’s crust contains on the average about 0.05 part per million indium by weight. The element does not occur uncombined or in independent minerals but occurs as a trace in many minerals, particularly those of zinc and lead, from which it is obtained as a by-product.

Indium has the unusual property when molten of clinging to (wetting) clean glass and other surfaces; this makes it valuable for producing hermetic seals between glass, metals, quartz, ceramics, and marble. Indium is used in coating aircraft engine bearings because it improves corrosion resistance and enables the surface to retain a more adherent oil film. It is an ingredient in some low-melting alloys used in sprinkler heads, fire-door links, and fusible plugs. The metal is extensively employed in the manufacture of semiconductor devices and for soldering various parts of germanium transistors and rectifiers. Indium also is used to measure the thermal neutron flux of nuclear reactors and to monitor neutrons for the protection of personnel and equipment. Natural indium is a mixture of two isotopes: indium-113 (4.28 percent) and indium-115 (95.72 percent).

Indium metal is unaffected by air at ordinary temperatures, but at a red heat it burns with a blue-violet flame to form the yellow oxide In₂O₃. This oxide is easily reduced to the metal, and on strong heating it loses oxygen to give the monoxide, In₂O, where indium is in the +1 oxidation state. Indium hydroxide dissolves in both acids and alkalies.

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Indium is an amphoteric element; it dissolves in acids to give indium salts, and it also dissolves in concentrated alkalies to give indates. However, it is unaffected by potassium hydroxide or boiling water. When heated in the presence of the halogens or sulfur, direct combination takes place. Though a few authentic indium compounds (e.g., halides) have been prepared in which the element is in the +1 oxidation state, indium commonly displays the +3 state in its compounds. With the main Group 15 (Va) elements, indium forms compounds (indium nitride, indium phosphide, indium arsenide, indium antimonide) that have semiconductor properties. Nanostructured indium compounds have been developed, including indium nitride (InN) nanorods for high-speed field-effect transistors and light-emitting diodes (LEDs), which can be used in televisions and computer displays.

All anhydrous triply charged indium derivatives except indium trifluoride (InF₃) are covalent. There is a marked tendency for two of the outer electrons of the indium atom (the outer 5s² electrons) not to be used in bonding; this circumstance results in singly charged indium compounds.

Element Properties
atomic number	49
atomic weight	114.82
melting point	156.61 °C (313.89 °F)
boiling point	2,080 °C (3,776 °F)
specific gravity	7.31 (at 20 °C [68 °F])
oxidation states	+1, +3
electron config.	[Kr]4d¹⁰5s²5p¹

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Amy Tikkanen.

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