Indium Tech Report
Overview
Indium is part of the aluminum family in Group 13 (IIIA) of the periodic table. The periodic table is a chart that shows how chemical elements are related to each other. Indium was discovered in 1863 by German chemists Ferdinand Reich (1799-1882) and Hieronymus Theodor Richter (1824-98).
Indium has a number of interesting properties. For example, it has a low melting point for metals, 156.6°C (313.9°F). When pure, it sticks very tightly to itself or to other metals. This property makes it useful as a solder. Solder is a material used to join two metals to each other. Other uses of indium are in the manufacture of batteries, electronic devices, and in research.

SYMBOL
In

ATOMIC NUMBER
49

ATOMIC MASS
114.82

FAMILY
Group 13 (IIIA)
Aluminum

Physical properties
Indium is a silvery-white, shiny metal with a density of 7.31 grams per cubic centimeter. It is one of the softest metals known, even softer than lead. If drawn across a piece of paper, it leaves a mark like a "lead" pencil (which is actually carbon).
An unusual property of indium is that it produces a "tin cry." A tin cry is a scream-like sound made when the metal is bent.
Indium's main spectral lines are a brilliant indigo blue.
Indium has a melting point of 156.6°C (313.9°F) and a boiling point of 2,075°C (3,767°F). It has the unusual property of remaining soft and workable at very low temperatures. This property allows it to be used in special equipment needed for temperatures near absolute zero. Absolute zero is the coldest temperature possible. It is about —273°C (—459°F).

Chemical properties
Indium metal dissolves in acids, but does not react with oxygen at room temperature. At higher temperatures, it combines with oxygen to form indium oxide (In2O3).