Indium
Soft, silvery metal used in displays and semiconductors.
Indium is a chemical element with the symbol In and atomic number 49. It is a silvery-white post-transition metal, one of the softest elements, and is chemically intermediate between gallium and thallium. Indium is primarily used in flat-panel displays as indium tin oxide (ITO), a transparent conductive coating, and in semiconductors, low-melting-point alloys, and LED circuits.
- discoverers
- Ferdinand Reich and Hieronymus Theodor Richter
Lore & Background
They identified it by its distinctive indigo blue spectral line, leading to its name from the Latin 'indicum' meaning violet or indigo. The element is produced exclusively as a by-product of processing other metal ores, chiefly sphalerite and other zinc sulfide ores. Indium has no biological role, and its compounds are toxic when inhaled or injected, though poorly absorbed orally.
Reader's Guide
Indium's significance lies in its unique combination of physical and chemical properties. In the semiconductor industry, it is used in low-melting-point alloys, solders, and high-vacuum seals, and in manufacturing blue and white LED circuits via indium gallium nitride substrates. Its superconductivity below 3.41 K and its role as a by-product of zinc refining underscore its industrial importance. Chemically, indium exhibits both +1 and +3 oxidation states, with the +3 state being more common, and its compounds are used in organoindium chemistry for semiconductor precursors.
Did You Know?
- Indium is so soft (Mohs hardness 1.2) that it can be cut with a knife or bitten by human teeth.
- Indium leaves a visible line like a pencil when rubbed on paper.
- Indium dissolves in liquid mercury up to about 40–45% by mass at 0 °C, though some other metals like sodium or potassium are even more soluble.
Frequently Asked Questions
Who is Indium?
Indium is element number 49 on the periodic table, a silvery-white post-transition metal noted for being one of the softest elements in nature. It occupies Group 13, Period 5, sitting directly between gallium and thallium and sharing chemical traits with both neighbors.
What are Indium's powers/role?
Its most celebrated role is as a core component of indium tin oxide (ITO), the transparent conductive coating that makes touchscreens and flat-panel displays functional. It also appears in semiconductor devices, LED circuitry, and low-melting-point alloys used in niche engineering applications.
Why is Indium important?
Contemporary display technology is essentially inseparable from it, since the ITO layers on monitors, televisions, and smartphone screens rely on indium to carry electrical current while staying optically clear. It also supports semiconductor fabrication and specialized alloy work where a very low melting point is required.
Where does Indium sit in the periodic table?
It holds position 49 in Group 13, Period 5, which places it squarely between gallium above and thallium below. As a post-transition metal, it blends certain properties of both its vertical neighbors rather than fitting neatly into the classic transition-metal or alkali-metal categories.
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