CHROME

introduction

Numéro atomique: 24
Groupe: 6 or VI B
Poids atomique: 51.9961
Période: 4
Numero CAS: 7440-47-3

Classification

chalcogènes
Halogène
Gaz rare
lanthanides
actinides
Rare Earth Element
Groupe Platine Métal
Transuranium
Pas d'isotopes stables
Solide
Liquide
Gaz
Solide (prédit)

La description • Usages / Fonction

Discovered in 1797 by Vauquelin, who prepared the metal the next year, chromium is a steel-gray, lustrous, hard metal that takes a high polish.The principal ore is chromite (FeCr2O4), which is found in Zimbabwe, Russia, Transvaal, Turkey, Iran, Albania, Finland, Democratic Republic ofMadagascar, and the Philippines. The metal is usually produced by reducing the oxide with aluminum. Chromium is used to harden steel, tomanufacture stainless steel, and to form many useful alloys. Much is used in plating to produce a hard, beautiful surface and to prevent corrosion.Chromium is used to give glass an emerald green color. It finds wide use as a catalyst. All compounds of chromium are colored; the most importantare the chromates of sodium and potassium (K2CrO4) and the dichromates (K2Cr2O7) and the potassium and ammonium chrome alums, as KCr(SO4)2· 12H2O. The dichromates are used as oxidizing agents in quantitative analysis, also in tanning leather. Other compounds are of industrial value; leadchromate is chrome yellow, a valued pigment. Chromium compounds are used in the textile industry as mordants, and by the aircraft and other industriesfor anodizing aluminum. The refractory industry has found chromite useful for forming bricks and shapes, as it has a high melting point, moderatethermal expansion, and stability of crystalline structure. Many chromium compounds are toxic and should be handled with proper safeguards. Naturalchromium contains four isotopes. Sixteen other isotopes are known. Chromium metal (99.99%) costs about $200/kg. Commercial grade chromium(99%) costs about $75/kg. 1

• "Stainless steels show high tensile strength and excellent resistance to corrosion. The most common kind contains 14-18% chromium and 7-9% nickel." 2
• "insulin action…believed to promote the action of insulin and thus influences the metabolism of carbohydrates, fats, and proteins." 3

Propriétés physiques

Point de fusion:4*  1907 °C = 2180.15 K = 3464.6 °F
Point d'ébullition:4* 2671 °C = 2944.15 K = 4839.8 °F
sublimation point:4 
Triple point:4 
Point critique:4 
Densité:5  7.15 g/cm3

* - at 1 atm

Configuration de l'électron

Configuration de l'électron:  *[Ar] 4s1 3d5
Bloque: d
Plus haut niveau d'énergie occupés: 4
Électrons de valence: 

Nombres quantiques:

n = 3
ℓ = 2
m = 2
ms = +½

Bonding

Électronégativité (échelle de Pauling):6 1.66
Electropositivity (échelle de Pauling): 2.34
Electron Affinity:7 0.666 eV
oxydation États: +3,2,6
Fonction de travail:8 4.40 eV = 7.0488E-19 J

ionisation potentiel   eV 9  kJ/mol  
1 6.7665    652.9
2 16.4857    1590.6
3 30.96    2987.2
4 49.16    4743.2
5 69.46    6701.9
6 90.6349    8744.9
7 160.18    15455.0
8 184.7    17820.8
ionisation potentiel   eV 9  kJ/mol  
9 209.3    20194.4
10 244.4    23581.0
11 270.8    26128.2
12 298    28752.6
13 354.8    34233.0
14 384.168    37066.6
15 1010.6    97508.1
16 1097    105844.4
ionisation potentiel   eV 9  kJ/mol  
17 1185    114335.1
18 1299    125334.4
19 1396    134693.5
20 1496    144342.0
21 1634    157657.0
22 1721.4    166089.8
23 7481.7    721874.1
24 7894.81    761733.2

Thermochimie

Chaleur spécifique: 0.449 J/g°C 10 = 23.346 J/mol°C = 0.107 cal/g°C = 5.580 cal/mol°C
Conductivité thermique: 93.7 (W/m)/K, 27°C 11
Température de fusion: 16.9 kJ/mol 12 = 325.0 J/g
Chaleur de vaporisation: 344.3 kJ/mol 13 = 6621.7 J/g
État de la matière Enthalpie de formation (ΔHf°)14 Entropy (S°)14 Gibbs Free Energy (ΔGf°)14
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 5.645 23.61868 0 0
(ℓ) 6.239 26.103976 8.660 36.23344 5.340 22.34256
(g) 95.00 397.48 41.64 174.22176 84.27 352.58568

isotopes

Nuclide Masse 15 Demi vie 15 Spin nucléaire 15 Énergie de liaison
42Cr 42.00643(32)# 14(3) ms [13(+4-2) ms] 0+ 314.63 MeV
43Cr 42.99771(24)# 21.6(7) ms (3/2+) 331.08 MeV
44Cr 43.98555(5)# 54(4) ms [53(+4-3) ms] 0+ 350.33 MeV
45Cr 44.97964(54) 50(6) ms 7/2-# 363.99 MeV
46Cr 45.968359(21) 0.26(6) s 0+ 382.31 MeV
47Cr 46.962900(15) 500(15) ms 3/2- 395.97 MeV
48Cr 47.954032(8) 21.56(3) h 0+ 411.49 MeV
49Cr 48.9513357(26) 42.3(1) min 5/2- 422.36 MeV
50Cr 49.9460442(11) STABLE 0+ 435.09 MeV
51Cr 50.9447674(11) 27.7025(24) d 7/2- 445.02 MeV
52Cr 51.9405075(8) STABLE 0+ 456.82 MeV
53Cr 52.9406494(8) STABLE 3/2- 464.89 MeV
54Cr 53.9388804(8) STABLE 0+ 474.83 MeV
55Cr 54.9408397(8) 3.497(3) min 3/2- 481.04 MeV
56Cr 55.9406531(20) 5.94(10) min 0+ 489.11 MeV
57Cr 56.943613(2) 21.1(10) s (3/2-) 494.38 MeV
58Cr 57.94435(22) 7.0(3) s 0+ 501.52 MeV
59Cr 58.94859(26) 460(50) ms 5/2-# 505.87 MeV
60Cr 59.95008(23) 560(60) ms 0+ 512.08 MeV
61Cr 60.95472(27) 261(15) ms 5/2-# 516.42 MeV
62Cr 61.95661(36) 199(9) ms 0+ 522.63 MeV
63Cr 62.96186(32)# 129(2) ms (1/2-)# 526.04 MeV
64Cr 63.96441(43)# 43(1) ms 0+ 531.32 MeV
65Cr 64.97016(54)# 27(3) ms (1/2-)# 533.80 MeV
66Cr 65.97338(64)# 10(6) ms 0+ 539.08 MeV
67Cr 66.97955(75)# 10# ms [>300 ns] 1/2-# 541.56 MeV
Les valeurs marquées # ne sont pas purement dérivées des données expérimentales, mais au moins en partie des tendances systématiques. Spins avec de faibles arguments d'affectation sont entre parenthèses. 15

Réactions

Abondance

Terre - composés Source: oxides 19
Terre - Seawater: 0.0003 mg/L 20
Terre -  Croûte:  102 mg/kg = 0.0102% 20
Terre -  lithosphère:  0.012% 21
Terre -  Total:  4120 ppm 22
Planète Mercure) -  Total:  7180 ppm 22
Vénus -  Total:  4060 ppm 22
chondrites - Total: 6600 (relative to 106 atoms of Si) 23
Corps humain - Total: 0.000003% 24

composés

Information de sécurité


Fiche signalétique - ACI Alloys, Inc.

Pour plus d'informations

Liens externes:

Sources

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:9.
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 912.
(3) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 926-7.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(6) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(8) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(14) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(15) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(16) - Kotz, John C. and Treichel, Paul. Chemistry & Chemical Reactivity 4th ed.; Thomson Brooks/Cole: Belmont, CA, 1999; p 173.
(17) - Zumdahl, Steven and Zumdahl, Susan A. Chemistry 9th ed.; Brooks/Cole: Belmont, CA, 2014; p 131.
(18) - Atkins, Jones, and Laverman. Chemical Principles 6th ed.; W.H. Freeman and Company: New York, NY, 2013; p F94.
(19) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(20) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(21) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 964.
(22) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(23) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(24) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.