Chemical properties of Indium
- Atomic number:
- 49
- Atomic mass:
- 114.818 g.mol -1
- Electronegativity according to:
- 1.78
- Density:
- 7.13 g.cm-3 at 20°C
- Melting point:
- 156.60 °C
- Boiling point:
- 2072°C
- Vanderwaals radius:
- 0.193 nm
- Ionic radius:
- 0.155
- Isotopes:
- 39
- Electronic shell:
- [ Kr ] 4d10 5s2 5p1
- Energy of first ionisation:
- 558.3 kJ.mol -1
Lndium is a chemical element with symbol In and atomic number 49. It is a post-transition metallic element that is rare in Earth's crust. The metal is very soft, malleable and easily fusible, with a melting point higher than sodium, but lower than lithium or tin. Chemically, indium is similar to gallium and thallium, and it is largely intermediate between the two in terms of its properties.[5] It has no obvious role in biological processes and common compounds are not toxic. It is most notably used in low melting point metalalloys such as solders, in soft metal high vacuum seals, and in the production of transparent conductive coatings of indium tin oxide (ITO) on glass.
Applications
The first large-scale application for indium was as a coating for bearings in high-performance aircraft engines during World War II. Afterward, production gradually increased as new uses were found in fusible alloys, solders, and electronics. In the 1950s, tiny beads of it were used for the emitters and collectors of PNP alloy junction transistors. In the middle and late 1980s, the development of indium phosphide semiconductorsand indium tin oxide thin films for liquid crystal displays (LCD) aroused much interest. By 1992, the thin-film application had become the largest end use.
Indium in the environment
The lack of indium mineral deposits and the fact that indium is enriched in sulfidic lead, tin, copper, iron and predominately in zinc deposits, makes zinc production the main source for indium. The indium is leached from slag and dust of zinc production. Further purification is done byelectrolysis. The exact process varies with the exact composition of the slag and dust. Indium is produced mainly from residues generated during zinc ore processing but is also found in iron, lead, and copper ores. The amount of indium consumed is largely a function of worldwide LCD production.
Applications
The first large-scale application for indium was as a coating for bearings in high-performance aircraft engines during World War II. Afterward, production gradually increased as new uses were found in fusible alloys, solders, and electronics. In the 1950s, tiny beads of it were used for the emitters and collectors of PNP alloy junction transistors. In the middle and late 1980s, the development of indium phosphide semiconductorsand indium tin oxide thin films for liquid crystal displays (LCD) aroused much interest. By 1992, the thin-film application had become the largest end use.
Indium in the environment
The lack of indium mineral deposits and the fact that indium is enriched in sulfidic lead, tin, copper, iron and predominately in zinc deposits, makes zinc production the main source for indium. The indium is leached from slag and dust of zinc production. Further purification is done byelectrolysis. The exact process varies with the exact composition of the slag and dust. Indium is produced mainly from residues generated during zinc ore processing but is also found in iron, lead, and copper ores. The amount of indium consumed is largely a function of worldwide LCD production.
