Properties, History and Uses of Indium
Indium can be as a lustrous and silvery metal. This post-transition and ductile material is so malleable and soft that it can easily be scratched with fingernails and even bent into almost any shape. This silver-coloured metal has a tetragonal structure and is available in liquid form at varying temperatures. This makes it quite similar to gallium which belongs to the same group of metals. Both Gallium and Indium have the wet glass ability or the potential of sticking to the surface of the glass they are in contact with. Indium remains stable when it reacts with water and air but dissolves in acids. It transforms into a violet-coloured flame when heated over its basic melting point.
Indium is not found abundantly in nature, and it is worth noting that cultivated areas possess more of this metal than the non-cultivated regions. In nature, this is a rare metal found in the form of trace elements in various other minerals, specifically, lead and zinc. It is through these metals that Indium is obtained typically in the form of a by-product. The estimated availability of Indium in the Earth’s crust is approximately 0.1 ppm or parts per million. It is more abundant than mercury or silver as per reports by the Royal Society of Chemistry. Indium melting point is 156.6°C, which is low for any metal. If heated above this melting point, Indium transforms into an indigo or violet flame. The name of this metal comes from the bright light in indigo colour that it displays in the spectroscope.
Chemical and Physical Properties of Indium
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This image depicts the symbol of Indium.
The chemical and physical properties of Indium are as follows:
Indium melting and boiling point: 156.6°C and 2027°C, respectively.
Indium electron configuration: (Kr) 4d105s26p1
Indium atomic number: 49
Group: 13
Period: 5
Density: 7.31 g cm-3
Relative atomic weight: 114.818
Solid key isotopes: 115In
State at room temperature: Solid
Element categorization: Metal
An atomic symbol used in the periodic table of elements: In
Count of isotopes or atoms of the same element with a varied count of neutrons: 35 with half-lives, 2 occurring naturally and 1 stable.
Most common Indium isotope: In-115
Indium boiling point is 3681°for 2300K. This will probably offer you a clearer understanding of the boiling point of the Indium element.
The History of the Discovery of Indium
The well-known chemists from Germany, namely Hieronymus Theodor Richter and Ferdinand Reich discovered Indium in the year 1863. Both Richter and Reich had long been in the lookout of traces of thallium elements in samples of different zinc deposits and ores. It was only when a bright and brilliant indigo line appeared in the spectrum of a sample that the chemists came to know about the existence and the availability of Indium. The metal has the same natural abundance as silver; however, it can be recovered more conveniently and easily than silver because it typically appears along with iron, copper, zinc and lead ores.
Indium Uses
One of the most prominent uses of this metal is as casting for the bearings in high-speed motors. This is because Indium makes way for the even distribution of the lubricating oils used in these motors. The metal is also ideal for doping germanium in the manufacturing procedure of transistors. Indium is even used for making various other electronic elements like thermistors, photoconductors and rectifiers. You can use it for making mirrors that seem to be more reflective in comparison to silver mirrors but have a long shelf life and do not get tarnished very quickly. Indium works out to be the best metal when used for making low melting alloys. At room temperature, an alloy made with 76% gallium, and 24% indium stays in a liquid state.
Other Uses of Indium are as Follows:
Used in semiconductor firms for the manufacture of diodes.
Used for manufacturing bearings that are moisture-resistant and the ones that improve anti-seizure characteristics.
Utilized in different plating applications.
Indium Uses in Everyday Life
In these present times, Indium seems to be one of the essential elements for the economies of the world. ITO or Indium Tin Oxide is widely used in different manufacturing procedures practised at varied industries and even in the everyday life of individuals. This is one form of the element Indium that serves to be one of the best materials for filling the growing requirements of LCDs or liquid crystal displays along with solar panels, TVs, flat screens and touch screens.
Different properties of this element make it ideal for flat panel displays and LCDs. These include transparency, adhering very strongly to glass, conducting electricity, mechanical and chemical corrosion resistance.
FAQs on Indium
1. What is indium and what are its main uses?
Indium is a soft, silvery-white metal belonging to Group 13 of the periodic table. It is quite rare and has some very specific, important uses in modern technology. The most common applications are:
- Electronics: It is a key ingredient in Indium Tin Oxide (ITO), which is a transparent material that conducts electricity. This makes it essential for manufacturing LCD screens, touchscreens, and solar panels.
- Alloys: Indium is used to make low-melting-point alloys and solders.
- Coatings: It can be used to coat bearings in high-performance engines, protecting them from wear and corrosion.
2. What are some of the most interesting physical properties of indium?
Indium has several unique physical properties. It is so soft that you can cut it with a knife and it leaves a line on paper, similar to lead. When a bar of pure indium is bent, it makes a high-pitched squeaking sound known as a 'tin cry'. It also has a very low melting point for a metal and has the unusual ability to stick to glass when molten.
3. Is indium named after the country India?
No, this is a common misconception. Indium was not named after India. It was discovered in 1863 by German chemists Ferdinand Reich and Hieronymus Richter. They named it 'indium' because of the bright indigo-blue line they saw in its atomic spectrum while using spectroscopy.
4. How and where is indium found in nature?
Indium is not found in its pure, elemental form in nature. It is a relatively rare element and is typically obtained as a byproduct of processing other metal ores. The primary source of indium is from residues generated during zinc ore processing, particularly from the mineral sphalerite.
5. Why is indium considered an expensive and critical element?
Indium's high cost and critical status are due to a combination of factors. Firstly, it is rare in the Earth's crust and its extraction is dependent on zinc mining. Secondly, there is an extremely high demand for it, especially for producing Indium Tin Oxide (ITO) for the booming electronics industry (smartphones, TVs, etc.). This supply-demand imbalance makes it both expensive and strategically important.
6. Is indium toxic or harmful to humans?
Pure indium metal is generally considered to have low toxicity. However, indium compounds should be handled with care as they can be harmful if inhaled or ingested. They may affect the lungs, liver, and kidneys. Indium has no known biological role in the human body, so exposure should be minimised.
7. How does indium’s position in the periodic table affect its chemical properties?
Indium is in Group 13, under aluminium and gallium. Like other elements in this group, it has three valence electrons and commonly forms a +3 oxidation state. However, due to a phenomenon called the inert pair effect, which becomes significant for heavier elements in the p-block, indium can also exhibit a stable +1 oxidation state. This effect explains why indium can form compounds like InCl as well as InCl₃.
