Editing Period 5 element (section)

===Indium===
{{main|Indium}}
'''Indium''' is a [[chemical element]] with the symbol '''In''' and [[atomic number]] 49. This rare, very soft, malleable and easily [[Fusible alloy|fusible]] [[other metal]] is chemically similar to [[gallium]] and [[thallium]], and shows the intermediate properties between these two. Indium was discovered in 1863 and named for the [[indigo blue]] line in its spectrum that was the first indication of its existence in zinc ores, as a new and unknown element. The metal was first isolated in the following year. Zinc ores continue to be the primary source of indium, where it is found in compound form. Very rarely the element can be found as grains of native (free) metal, but these are not of commercial importance.

Indium's current primary application is to form transparent electrodes from [[indium tin oxide]] in [[liquid crystal display]]s and [[touchscreen]]s, and this use largely determines its global mining production. It is widely used in thin-films to form lubricated layers (during [[World War II]] it was widely used to coat bearings in high-performance [[aircraft]]). It is also used for making particularly low melting point alloys, and is a component in some lead-free solders.

Indium is not known to be used by any organism. In a similar way to aluminium salts, indium(III) ions can be toxic to the kidney when given by injection, but oral indium compounds do not have the chronic toxicity of salts of heavy metals, probably due to poor absorption in basic conditions. Radioactive indium-111 (in very small amounts on a chemical basis) is used in [[nuclear medicine]] tests, as a [[radiotracer]] to follow the movement of labeled proteins and [[indium leukocyte imaging|white blood cells]] in the body.