GALLIO

introduzione

Numero atomico: 31
Gruppo: 13 or III A
Peso atomico: 69.723
Periodo: 4
Numero CAS: 7440-55-3

Classificazione

Metallo
Metalloide
simile a metallo
metallo alcalino
Alkali terroso
Metallo di transizione
calcogeno
alogena
Gas nobile
Lanthanoid
Actinoid
Terre rare
Platinum Metal Group
transuranici
Non ci sono isotopi stabili
Solido
Liquido
Gas
Solido (previsto)

Descrizione • Usi / Funzione

Predicted and described by Mendeleev as ekaaluminum, and discoveredspectroscopically by Lecoq de Boisbaudran in 1875, who in the same year obtained the free metal by electrolysis of a solution of the hydroxide in KOH.Gallium is often found as a trace element in diaspore, sphalerite, germanite, bauxite, and coal. Some flue dusts from burning coal have been shownto contain as much as 1.5% gallium. It is the only metal, except for mercury, cesium, and rubidium, which can be liquid near room temperatures; thismakes possible its use in high-temperature thermometers. It has one of the longest liquid ranges of any metal and has a low vapor pressure even at hightemperatures. There is a strong tendency for gallium to supercool below its freezing point. Therefore, seeding may be necessary to initiate solidification.Ultra-pure gallium has a beautiful, silvery appearance, and the solid metal exhibits a conchoidal fracture similar to glass. The metal expands 3.1% onsolidifying; therefore, it should not be stored in glass or metal containers, as they may break as the metal solidifies. Gallium wets glass or porcelain,and forms a brilliant mirror when it is painted on glass. It is widely used in doping semiconductors and producing solid-state devices such as transistors.High-purity gallium is attacked only slowly by mineral acids. Magnesium gallate containing divalent impurities such as Mn+2 is finding use incommercial ultraviolet activated powder phosphors. Gallium arsenide is capable of converting electricity directly into coherent light. Gallium readilyalloys with most metals, and has been used as a component in low-melting alloys. Its toxicity appears to be of a low order, but should be handled withcare until more data are forthcoming. Natural gallium contains two stable isotopes. Twenty three other isotopes, one of which is an isomer, are known.The metal can be supplied in ultrapure form (99.99999+%). The cost is about $4/g. 1

• "It is used in transistors and high temperature thermometers. Gallium-67 was one of the first artificially produced isotopes to be used in medicine. It concentrates in inflamed areas and in certain melanomas." 2
• "Perfectly conducting materials al!ow electrons to move freely among the atoms of the material. At normal temperatures, there are no perfect conductors, but metals like silver and copper are very good.

Semiconductors, on the other hand, rely on the jumping of electrons between accessible energy levels for current to flow in the material. In a solid, these levels are more numerous than in a gas of the same species and form broad bands of available energies, allowing for large congregations of electrons. These electrons undergo random thermal motion, but cannot jump to the next energy band if the gap between bands is much greater than the average thermal energy. So current flow in semiconductors is strongly dependent on the ambient temperature. Electrons can also be made to jump between bands if they absorb energy in any other form, such as electromagnetic energy. An applied electric field or light absorption can make current flow in semiconductors. It is this property that makes them useful in circuits - small amounts of current can be made to flow at prescribed moments. This is an important property in transistors, optoelectronics, and solar cells.

The energy bandwidths and gaps are also dependent on the exact nature of the material. Silicon and germanium, for example, are good semiconductors, while carbon is not, though all three have similar electronic structure. (Note that they inhabit the same column in the periodic table.) The difference is that, in solid form, the gaps between the two highest energy levels in silicon and germanium are much smaller than in carbon, so electrons are able to transition between them with ease. The addition of tiny bits of impurities can also have an impressive effect on the bandwidths and gaps.

A small amount of arsenic added to crystal gallium has resulted in a material (gallium arsenide or GaAs) that is particularly well adapted to many important semiconductor applications. Compared to the more common silicon semiconductors, GaAs displays relatively low sensitivity to heat, higher electron mobility, and the ability to withstand higher applied voltages. This means that GaAs transistors can be operated at higher frequencies and higher power with less associated noise.The nature of the band gap in GaAs also means that it is better at emitting light than silicon semiconductors, making it a material of choice for light-emitting diodes (LEDs). Though gallium is much more expensive than silicon, its high absorptivity allows for very thin films to be used as efficient collectors for solar cells. It has been used for this purpose in several Mars rovers.

Challenges for the GaAs applications include its expense. Researchers are working on finding appropriate inexpensive substrates for growth of the GaAs wafers or films. In addition, arsenic is toxic and carcinogenic, so great care must be taken toward worker safety in the wafer-polishing process." 3
• "Almost all of the world's gallium supply is used in the electronics industry along with other applications and may be found in radios, televisions, and calculators. Gallium arsenide and gallium phosphide are used in a variety of semiconductor devices, including diodes and laser diodes, and may be found in computers and cell phones. Gallium arsenide is also used in solar batteries. Small amounts of gallium are found in thermometers, solders, arc lamps, batteries, and catalysts." 4

Proprietà fisiche

Punto di fusione:5
Punto di ebollizione:5* 2204 °C = 2477.15 K = 3999.2 °F
sublimazione Point:5 
Triple Point:5 29.771 °C = 302.921 K = 85.5878 °F
Punto critico:5 
Densità:6  5.91 g/cm3

* - at 1 atm

configurazione elettronica

configurazione elettronica: [Ar] 4s2 3d10 4p1
Bloccare: p
Più alto livello di energia Occupato: 4
Elettroni di valenza: 3

numeri quantici:

n = 4
ℓ = 1
m = -1
ms = +½

bonding

elettronegatività (scala Pauling):7 1.81
Electropositivity (scala Pauling): 2.19
Affinità elettronica:8 0.43 eV
ossidazione Uniti: +3
Funzione di lavoro:9 4.25 eV = 6.8085E-19 J

potenziale di ionizzazione   eV 10  kJ/mol  
1 5.9993    578.8
potenziale di ionizzazione   eV 10  kJ/mol  
2 20.5142    1979.3
potenziale di ionizzazione   eV 10  kJ/mol  
3 30.71    2963.1
4 64    6175.1

Termochimica

Calore specifico: 0.371 J/g°C 11 = 25.867 J/mol°C = 0.089 cal/g°C = 6.182 cal/mol°C
Conduttività termica: 40.6 (W/m)/K, 27°C 12
Calore di fusione: 5.59 kJ/mol 13 = 80.2 J/g
Calore di vaporizzazione: 258.7 kJ/mol 14 = 3710.4 J/g
Stato della materia Entalpia di formazione (ΔHf°)15 entropia (S°)15 Energia libera di Gibbs (ΔGf°)15
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 9.77 40.87768 0 0
(g) 66.2 276.9808 40.38 168.94992 57.1 238.9064

isotopi

nuclide Massa 16 Metà vita 16 spin nucleare 16 Energia di legame
56Ga 55.99491(28)# 3+# 433.33 MeV
57Ga 56.98293(28)# 1/2-# 452.58 MeV
58Ga 57.97425(23)# 2+# 468.10 MeV
59Ga 58.96337(18)# 3/2-# 486.42 MeV
60Ga 59.95706(12)# 70(10) ms (2+) 500.08 MeV
61Ga 60.94945(6) 168(3) ms 3/2- 515.60 MeV
62Ga 61.944175(30) 116.18(4) ms 0+ 528.33 MeV
63Ga 62.9392942(14) 32.4(5) s (3/2-) 541.06 MeV
64Ga 63.9368387(22) 2.627(12) min 0(+#) 551.93 MeV
65Ga 64.9327348(9) 15.2(2) min 3/2- 563.72 MeV
66Ga 65.931589(3) 9.49(7) h 0+ 572.73 MeV
67Ga 66.9282017(14) 3.2612(6) d 3/2- 583.59 MeV
68Ga 67.9279801(16) 67.71(9) min 1+ 592.59 MeV
69Ga 68.9255736(13) STABILE 3/2- 602.53 MeV
70Ga 69.9260220(13) 21.14(3) min 1+ 609.67 MeV
71Ga 70.9247013(11) STABILE 3/2- 619.60 MeV
72Ga 71.9263663(11) 14.095(3) h 3- 625.81 MeV
73Ga 72.9251747(18) 4.86(3) h 3/2- 634.81 MeV
74Ga 73.926946(4) 8.12(12) min (3-) 641.95 MeV
75Ga 74.9265002(26) 126(2) s (3/2)- 650.03 MeV
76Ga 75.9288276(21) 32.6(6) s (2+,3+) 656.23 MeV
77Ga 76.9291543(26) 13.2(2) s (3/2-) 663.37 MeV
78Ga 77.9316082(26) 5.09(5) s (3+) 669.58 MeV
79Ga 78.93289(11) 2.847(3) s (3/2-)# 676.72 MeV
80Ga 79.93652(13) 1.697(11) s -3 681.07 MeV
81Ga 80.93775(21) 1.217(5) s (5/2-) 688.21 MeV
82Ga 81.94299(32)# 0.599(2) s (1,2,3) 691.62 MeV
83Ga 82.94698(32)# 308(1) ms 3/2-# 695.97 MeV
84Ga 83.95265(43)# 0.085(10) s 698.45 MeV
85Ga 84.95700(54)# 50# ms [>300 ns] 3/2-# 701.86 MeV
86Ga 85.96312(86)# 30# ms [>300 ns] 704.34 MeV
I valori assegnati # non sono puramente derivati ​​da dati sperimentali, ma almeno parzialmente da tendenze sistematiche. Gira con argomenti di assegnazione deboli sono racchiusi tra parentesi. 16

Abbondanza

Terra - composti di origine: oxides 17
Terra - L'acqua di mare: 0.00003 mg/L 18
Terra -  Crosta:  19 mg/kg = 0.0019% 18
Terra -  Totale:  3.1 ppm 19
Pianeta Mercurio) -  Totale:  0.50 ppm 19
Venere -  Totale:  3.4 ppm 19
condriti - Totale: 12 (relative to 106 atoms of Si) 20

Composti

Informazioni sulla sicurezza


Scheda di sicurezza - ACI Alloys, Inc.

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fonti

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:13.
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 933.
(3) - Halka, Monica and Nordstrom, Brian. Metals & Metalloids; Infobase Publishing: New York, NY, 2011; pp 27-28.
(4) - Halka, Monica and Nordstrom, Brian. Metals & Metalloids; Infobase Publishing: New York, NY, 2011; p 31.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(7) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(9) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(14) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(15) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(16) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(17) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(18) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(19) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(20) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.