|
General |
Name, Symbol, Number | Indium, In, 49 |
Chemical series | True metals[?] |
Group, Period, Block | 13 (IIIA)[?], 5 , p |
Density, Hardness | 7310 kg/m3, 1.2 |
Appearance | silvery lustrous gray |
Atomic Properties |
Atomic weight | 114.818 amu |
Atomic radius (calc.) | 155 (156) pm |
Covalent radius | 144 pm |
van der Waals radius | 193 pm |
Electron configuration | [Kr]4d10 5s2 5p1 |
e- 's per energy level | 2, 8, 18, 18, 3 |
Oxidation states (Oxide) | 3 (amphoteric) |
Crystal structure | Tetragonal |
Physical Properties |
State of matter | solid |
Melting point | 429.75 K (313.88 °F) |
Boiling point | 2345 K (3762 °F) |
Molar volume | 15.76 ×10-3 m3/mol |
Heat of vaporization | 231.5 kJ/mol |
Heat of fusion | 3.263 kJ/mol |
Vapor pressure | 1.42 E-17 Pa at 429 K |
Speed of sound | 1215 m/s at 293.15 K |
Miscellaneous |
Electronegativity | 1.78 (Pauling scale) |
Specific heat capacity | 233 J/(kg*K) |
Electrical conductivity | 11.6 106/m ohm |
Thermal conductivity | 81.6 W/(m*K) |
1st ionization potential | 558.3 kJ/mol |
2nd ionization potential | 1820.7 kJ/mol |
3rd ionization potential | 2704 kJ/mol |
4th ionization potential | 5210 kJ/mol |
Most Stable Isotopes |
|
SI units & STP are used except where noted. |
Indium is a
chemical element in the
periodic table that has the symbol In and
atomic number 49. This rare, soft, malleable and easily fusible
true metal[?], is chemically similar to
aluminum or
gallium but looks more like
zinc (zinc ores are also the primary source of this metal). Its current primary application is to form thin-films for use as lubricated layers (during
WWII it was widely used to coat bearings in high-performance
aircraft).
Indium is a very soft, silvery-
white true metal[?] that has a bright
luster. As a pure metal indium emits a high-pitched "cry" when it is bent. Both
gallium and indium are able to wet
glass.
The first large-scale application for indium was as a coating for
bearings in high-performance
aircraft engines during
World War II. Afterwards, production gradually increased as new uses were found in fusible
alloys,
solders, and
electronics. In the middle and late
1980s, the development of indium phosphide
semiconductors and 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. Other uses;
Indium (named after the
indigo line in its
atomic spectrum[?]) was discovered by
Ferdinand Reich[?] and
Theodore Richter[?] in
1863 while they were testing
zinc ores with a
spectrograph in search of
thallium. Richter went on to isolate the metal in
1867.
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. Increased manufacturing efficiency and recycling (especially in
Japan) maintain a balance between demand and supply. The average indium price for 2000 was
US$188 per
kilogram.
Up until 1924, there was only about a gram of isolated indium on the planet. The Earth is estimated to contain abou 0.1 ppm of indium which means it is about as abundant as silver. Canada is a leading producer of indium, producing more than 1,000,000 troy ounces in 1997.
There is some unconfirmed evidence that suggests that indium has a low level of
toxicity. However in the
welding and semiconductor industries, where indium exposure is relatively high, there have been no reports of any toxic side-effects.