Gallium




31 germanium
Al
↑
Ga
↓
In
General
Number gallium, Ga, 31
poor metals
Block 13, p
Appearance silvery white
 
(1)  g·mol−1
Ar] 3d10 4s2 4p1
shell 2, 8, 18, 3
Physical properties
Phase solid
r.t.) 5.91  g·cm−3
Liquid m.p. 6.095  g·cm−3
F)
F)
kJ·mol−1
kJ·mol−1
Heat capacity (25 °C) 25.86  J·mol−1·K−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 1310 1448 1620 1838 2125 2518
Atomic properties
Crystal structure orthorhombic
amphoteric oxide)
Electronegativity 1.81 (Pauling scale)
more) 1st:  578.8  kJ·mol−1
2nd:  1979.3  kJ·mol−1
3rd:  2963  kJ·mol−1
Atomic radius 130  pm
Atomic radius (calc.) 136  pm
Covalent radius 126  pm
Van der Waals radius 187 pm
Miscellaneous
Magnetic ordering no data
Thermal conductivity (300 K) 40.6  W·m−1·K−1
Speed of sound (thin rod) (20 °C) 2740 m/s
Mohs hardness 1.5
Brinell hardness 60  MPa
CAS registry number 7440-55-3
Selected isotopes
Main article: Isotopes of gallium
iso NA half-life DM DE (MeV) DP
69Ga 60.11% Ga is neutrons
71Ga 39.89% Ga is neutrons
References

Gallium (light-emitting diodes (LEDs).

Notable characteristics

Elemental gallium is not found in nature, but it is easily obtained by smelting. Very pure gallium metal has a brilliant silvery color and its solid metal fractures antimony and water.

Gallium also alloys[1] or steel.[2], making them very brittle. Also, Gallium metal easily alloys with many metals,[citation needed] and was used in small quantities in the core of the first atomic bomb to help stabilize the plutonium crystal structure.[citation needed]

The wets glass and skin, making it mechanically more difficult to handle (even though it is substantially less toxic and requires far fewer precautions). For this reason as well as the metal contamination problem and freezing-expansion problems noted above, samples of gallium metal are usually supplied in polyethylene packets within other containers.

Gallium does not metastable phases are found as function of temperature and pressure.

The bonding between the nearest neighbors is found to be of light-emitting diodes.

High-purity gallium is attacked slowly by mineral acids.

History

Gallium (the Latin Gallia means "Gaul," essentially modern France; and the Latin gallus means "rooster") was discovered hydroxide in potassium hydroxide solution. He named the element "gallia" after his native land of France. It was later claimed that, in one of those multilingual puns so beloved of men of science in the early 19th century, he had also named gallium after himself, as his name, "Lecoq," is the French for "the rooster," and the Latin for "rooster" is "gallus"; however, in an 1877 article Lecoq denied this supposition.

Occurrence

Gallium does not exist in free form in nature, nor do any high-gallium minerals exist to serve as a primary source of extraction of the element or its compounds. Gallium is found and extracted as a trace component in sphalerite. The United States Geological Survey (USGC) estimates gallium reserves based on 50 ppm by weight concentration in known reserves of bauxite and zinc ores. Some flue dusts from burning coal have been shown to contain small quantities of gallium, typically less than 1 % by weight.[3][4][5][6]

Most gallium is extracted from the crude zone melting, or else single crystal extraction from a melt (Czochralski process). Purities of 99.9999% are routinely achieved and commercially widely available.

The current price for 1 gram gallium of 99.9999% purity seems to be at about US $15.00.[citation needed]

Applications

Semiconductor and electronic industry. The semiconductor applications are the main reason for the low-cost commercial availability of the extremely high-purity (99.9999+%) metal:

  • As a component of the semiconductor light-emitting diodes.)
  • Gallium is used widely as a semiconductors and produce solid-state devices like transistors.
  • Gallium is the rarest component of new photovoltaic compounds (such as copper indium gallium selenium sulphide or Cu(In,Ga)(Se,S)2, recently announced by South African researchers) for use in solar panels as an alternative to crystalline silicon, which is currently in short supply.

As a wetting, and alloy improvement agent:

  • Because gallium porcelain, gallium can be used to create brilliant mirrors.
  • Gallium readily allotropes of plutonium.
  • Gallium added in quantities up to 2% in common solders can aid wetting and flow characteristics.

As part of an energy storage mechanism:

  • Aluminium is reactive enough to reduce water to aluminium oxide. However, the aluminium oxide forms a protective coat which prevents further reaction. When gallium is alloyed with aluminium, the coat does not form, thus the alloy can potentially provide a solid hydrogen source for transportation purposes, which would be more convenient than a pressurized hydrogen tank. Resmelting the resultant aluminum oxide and gallium mixture to metallic aluminum and gallium and reforming these into electrodes would constitute most of the energy input into the system, while electricity produced by a hydrogen fuel cell could constitute an energy output.[7][8]The thermodynamic efficiency of the aluminum smelting process is said to be approximately 50 percent.[citation needed] Therefore, at most no more than half the energy that goes into smelting aluminum could be recovered by a fuel cell.

For liquid alloys:

  • It has been suggested that a liquid gallium-tin alloy could be used to cool computer chips in place of water. As it conducts heat approximately 65 times better than water it can make a comparable coolant. [2]
  • Gallium is used in some high temperature thermometers.

Biomedical applications:

  • A low temperature liquid tin, is widely available in medical thermometers (fever thermometers), replacing problematic mercury. This alloy, with the trade name Galinstan (with the "-stan" referring to the tin), has a freezing point of −20°C.
  • Gallium positron emission tomography, "PET" scan.
  • Gallium nitrate, both oral and topical, is finding use in treating arthritis.[9]
  • Much research is being devoted to gallium alloys as substitutes for mercury dental amalgams, but these compounds have yet to see wide acceptance.
  • Research is being conducted to determine whether gallium can be used to fight bacterial infections in people with cystic fibrosis. Gallium is similar in size to iron, an essential nutrient for respiration. When gallium is mistakenly picked up by bacteria such as Pseudomonas, the bacteria's ability to respire is interfered with and the bacteria die. The mechanism behind this is that iron is redox active, which allows for the transfer of electrons during respiration, but gallium is redox inactive. [10][11]

Miscellaneous:

  • phosphor powder.
  • Ge-71, which were detected. The solar neutrino flux deduced was found to have a deficit of 40% from theory. This was not explained until better solar neutrino detectors and theories were constructed (see SNO).[3]
  • As a liquid metal ion source for a focused ion beam.

Precautions

While not considered toxic, the data about gallium are inconclusive. Some sources suggest that it may cause dermatitis from prolonged exposure; other tests have not caused a positive reaction. Like most metals, finely divided gallium loses its luster. Powdered gallium appears gray. When gallium is handled with bare hands, the extremely fine dispersion of liquid gallium droplets which results from wetting skin with the metal may appear as a gray skin stain.

See also

References

  • Los Alamos National Laboratory – Gallium
  • Webelements: detailed information on gallium
  1. ^ W. L. Tsai, Y. Hwu, C. H. Chen, L. W. Chang, J. H. Je, H. M. Lin, G. Margaritondo (2003). "Grain boundary imaging, gallium diffusion and the fracture behavior of Al–Zn Alloy – An in situ study". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 199: 457-463. doi:10.1016/S0168-583X(02)01533-1.
  2. ^ Vigilante, G. N., Trolano, E., Mossey, C. (Jun 1999). Liquid Metal Embrittlement of ASTM A723 Gun Steel by Indium and Gallium. Defense Technical Information Center.
  3. ^ Shan Xiao-quan, Wang Wen and Wen Bei (1992). "Determination of gallium in coal and coal fly ash by electrothermal atomic absorption spectrometry using slurry sampling and nickel chemical modification". J. Anal. At. Spectrom. 7: 761 - 764. doi:10.1039/JA9920700761.
  4. ^ Gallium in West Virginia Coals. West Virginia Geological and Economic Survey (2 Mar 2002).
  5. ^ O. Font, X. Querol, R. Juan, R. Casado, C. R. Ruiz, A. Lopez-Soler, P. Coca and F. G. Pena (2007). "Recovery of gallium and vanadium from gasification fly ash". Journal of Hazardous Materials 139 (3): 413-423. doi:10.1016/j.jhazmat.2006.02.041.
  6. ^ A. J. W. Headlee and Richard G. Hunter (1953). "Elements in Coal Ash and Their Industrial Significance". Industrial and Engineering Chemistry 45 (3): 548 - 551. doi:10.1021/ie50519a028.
  7. ^ Purdue University (April 10, 2007). "Purdue Energy Center symposium to pave the road to a hydrogen economy". Press release.
  8. ^ "New process generates hydrogen from aluminum alloy to run engines, fuel cells", PhysOrg.com, 16 May 2007. 
  9. ^ G. Eby (2005). "Elimination of arthritis pain and inflammation for over 2 years with a single 90 min, topical 14% gallium nitrate treatment: Case reports and review of actions of gallium III". Medical Hypotheses 65 (6): 1136-1141. doi:10.1016/j.mehy.2005.06.021.
  10. ^ A Trojan-horse strategy selected to fight bacteria
  11. ^ Gallium May Have Antibiotic-Like Properties
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Gallium". A list of authors is available in Wikipedia.