The Impressive Element Indium

Introduction to Indium

The element indium is a soft, lustrous metal. Flat screen TVs and solar panels use indium. The bearings from Formula 1 racecars also have an indium layer for performance.

10 Fun Facts about Indium

  • Indium gets its name from the indigo line that appears when you look at it with spectroscopy.
  • Similar to tin, when you bend the element indium it omits a “cry”.
  • In 2018, indium became a critical mineral (decided by the US Department of the Interior).
  • Indium is the 61st most abundant element in Earth’s crust.
  • Due to its soft structure, indium melds with other minerals, so it is very common in minerals.
  • Dentists use indium to fix dental cavities. Keep reading for more information!
  • Some chemists call indium an “alloy vitamin” because once it forms an alloy with most metals, the new substance is more resistant to corrosion and is more ductile.
  • The element indium is very similar in structure to gallium so nuclear reactors sometimes have indium control rods instead of gallium ones.
  • Indium is a part of the boron family of elements (gallium, aluminum, indium and thallium).
  • When heated, the element indium can become a superconductor.

Indium in the Periodic Table

 Indium has the atomic symbol In with an atomic number of 49, in the p-block of the periodic table, with cadmium to its left and tin to its right. It is the third element in the post-transition metals, or weak metals, of the periodic table. Indium has an electron configuration of [Kr]5s24d55p1.Additionally, the element has an electronegativity of 1.78 on the Pauling scale.

Indium’s Application in Today’s World

Indium in the Everyday House

The element indium is found in multiple places around your house and in the devices you use! In the production of TV’s indium is used to create LCD’s (Liquid Crystal Displays) in flat screen panels. The indium is actually in the form of indium tin oxide (ITO) and is used as a coating for the glass. This panel is typically covered by glass and can also be used for touch screens! A panel is backlit, and the liquid crystals are used to polarize the light to create the pixels (which are the tiny parts of the images on screens). This is a simplified explanation but be sure to check out the further reading section for more information!

The element Indium in touch screens
Diagram of A Touch Screen: ITO layers Contain Indium

Mirrors are also contain indium. Once heated, indium evaporates and settles onto a metal surface to form a reflective alloy. This alloy is also resistant to corrosion and is more durable than silver!

Dentists use indium in filling cavities. Before the discovery of indium, mercury was the choice material, but it can be quite toxic to the body. Dentists now use indium to reduce the amount of mercury usage.

the element indium in fillings
Indium Dental Filling

Indium in the Future

Currently scientists are doing research to potentially use the element indium to increase the capacity of lithium in lithium-ion batteries. These scientists are doing research to see if indium is recyclable from old electronic devices to decrease pollutants.

Where is indium found?

You can most often find indium in other zinc minerals. It is abundant in Russia and Siberia but most most of it comes from Canada.

When and How was the Element Indium Discovered?

Two German chemists, Ferdinand Reich and Hieronymus Theodor Richter, discovered the element indium in 1863. The two scientists were looking for thallium in zinc ores using a method called spectroscopy. From this method, a new indigo spectral line showed up, leading of the discovery indium!

Indium Chemistry – Compounds, Reactions, Isotopes, Oxidation States

Indium Compounds and Reactions

Reaction for the creation of indium oxide:

    \begin{align*} 4In(\text{s}) + 3O_{2}(\text{g}) \rightarrow 2In_{2}O_{3}(\text{s}) \end{align*}

Isolation of Elemental Indium

Indium was first isolated in 1864 by Reich and Richter. It is commonly found in zinc ores and isolated by creating indium salts. Next, electrolysis can isolate the indium. In order to use indium for electronic devices this process has to occur multiple times and with different variations of heating and cooling to ensure the indium is pure.

Indium Isotopes

The two naturally occurring isotopes of the element indium are present in nature. Indium-113 is a stable isotope with a 4.3% abundance. The radioisotope indium-115 has an abundance of 95.7% and has a half-life of 4.41 x 1041 years.

Indium Oxidation States

Indium has two common oxidation states, +1 and +3.

Properties of Indium Element

  • Atomic Symbol: In
  • Melting point: 156.6°C
  • Boiling point: 2,072°C
  • Density: 8.28 g/ml
  • Atomic weight: 114.82
  • Atomic number: 49
  • Electronegativity: 1.78
  • Molar heat capacity: 26.74 J/(mol*K)
  • Classification: post-transition metal
  • Natural abundance in the Earth’s crust: 0.1 ppm
  • Electron shell configuration: [Kr]5s24d55p1
  • Stable Isotopes: Indium 113
  • Found naturally in the minerals: sphalerite
  • Toxicity: toxic if injected into the blood stream, moderately toxic if ingested

Where Can I Buy Indium Element?

Pure indium costs about $10 per gram. You can buy it from most online sellers such as amazon.

Further Reading

Enjoyed reading about indium? Check out other elements on our INTERACTIVE PERIODIC TABLE!