CALCIUM

introduction

Numéro atomique: 20
Groupe: 2 or II A
Poids atomique: 40.078
Période: 4
Numero CAS: 7440-70-2

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

Though lime was prepared by the Romans in the first century under the name calx, the metal was not discovered until 1808. After learning that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, Davy was able to isolate the impure metal. Calcium is a metallic element, fifth in abundance in the earth’s crust, of which it forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone (CaCO3), gypsum (CaSO4 · 2H2O), and fluorite (Caf2); apatite is the fluorophosphate or chlorophosphate of calcium. The metal has a silvery color, is rather hard, and is prepared by electrolysis of the fused chloride to which calcium fluoride is added to lower the melting point. Chemically it is one of the alkaline earth elements; it readily forms a white coating of oxide in air, reacts with water, burns with a yellow-red flame, forming largely the oxide. The metal is used as a reducing agent in preparing other metals such as thorium, uranium, zirconium, etc., and is used as a deoxidizer, desulfurizer, and inclusion modifier for various ferrous and nonferrous alloys. It is also used as an alloying agent for aluminum, beryllium, copper, lead, and magnesium alloys, and serves as a “getter” for residual gases in vacuum tubes, etc. Its natural and prepared compounds are widely used. Quicklime (CaO), made by heating limestone and changed into slaked lime by the careful addition of water, is the great cheap base of chemical industry with countless uses. Mixed with sand it hardens as mortar and plaster by taking up carbon dioxide from the air. Calcium from limestone is an important element in Portland cement. The solubility of the carbonate in water containing carbon dioxide causes the formation of caves with stalactites and stalagmites and is responsible for hardness in water. Other important compounds are the carbide (CaC2), chloride (CaCl2), cyanamide (CaCN2), hypochlorite (Ca(OCl)2), nitrate (Ca(NO3)2), and sulfide (CaS). Natural calcium contains six isotopes. Thirteen other radioactive isotopes are known. Metallic calcium (99.5%) costs about $200/kg. 1

• "found primarily in the structural minerals comprising bones and teeth" 2
• "It has been suggested that magnesium, an essential component in chlorophyll, is removed from pine needles by the combined effects of ozone and acids...Another harmful effect of acid rain may be that it leaches essential metal ions such as Ca2+ and Mg2+ from soil as soluble salts." 3
• "used as a reducing agent in the metallurgy of uranium, thorium, and other metals. It is also used as a scavenger to remove dissolved impurities such as oxygen, sulfur, and carbon in molten metals and to remove the residual gases in vacuum tubes. It is a component of many alloys." 4
• "Reducing agent for production of less common metals' alloying agent to increase strength and corrosion resistance in lead, to improve mechanical and electrical properties in aluminum; refinign agent to remove bismuth from lead. In metallurgy as a scavenger to deoxidize, desulfurize and degas steel and cast iron; to control non-metallic inclusions in steel; to promote uniform microstructure in gray iron. As anode material in thermal batteries; as "getter" for oxygen and nitrogen." 5

Propriétés physiques

Point de fusion:6*  842 °C = 1115.15 K = 1547.6 °F
Point d'ébullition:6* 1484 °C = 1757.15 K = 2703.2 °F
sublimation point:6 
Triple point:6 
Point critique:6 
Densité:7  1.54 g/cm3

* - at 1 atm

Configuration de l'électron

Configuration de l'électron: [Ar] 4s2
Bloque: s
Plus haut niveau d'énergie occupés: 4
Électrons de valence: 2

Nombres quantiques:

n = 4
ℓ = 0
m = 0
ms = -½

Bonding

Électronégativité (échelle de Pauling):8 1.00
Electropositivity (échelle de Pauling): 3
Electron Affinity:9 0.02455 eV
oxydation États: +2
Fonction de travail:10 2.71 eV = 4.34142E-19 J

ionisation potentiel   eV 11  kJ/mol  
1 6.11316    589.8
2 11.87172    1145.4
3 50.9131    4912.4
4 67.27    6490.6
5 84.5    8153.0
6 108.78    10495.7
ionisation potentiel   eV 11  kJ/mol  
7 127.2    12272.9
8 147.24    14206.5
9 188.54    18191.3
10 211.275    20384.9
11 591.9    57109.7
12 657.2    63410.1
13 726.6    70106.2
ionisation potentiel   eV 11  kJ/mol  
14 817.6    78886.4
15 894.5    86306.1
16 974    93976.7
17 1087    104879.5
18 1157.8    111710.7
19 5128.8    494853.9
20 5469.864    527761.5

Thermochimie

Chaleur spécifique: 0.647 J/g°C 12 = 25.930 J/mol°C = 0.155 cal/g°C = 6.198 cal/mol°C
Conductivité thermique: 200 (W/m)/K, 27°C 13
Température de fusion: 8.54 kJ/mol 14 = 213.1 J/g
Chaleur de vaporisation: 153.3 kJ/mol 15 = 3825.0 J/g
État de la matière Enthalpie de formation (ΔHf°)16 Entropy (S°)16 Gibbs Free Energy (ΔGf°)16
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 9.90 41.4216 0 0
(ℓ) 2.61 10.92024 12.11 50.66824 1.96 8.20064
(g) 42.85 179.2844 36.99 154.76616 34.78 145.51952

isotopes

Nuclide Masse 17 Demi vie 17 Spin nucléaire 17 Énergie de liaison
34Ca 34.01412(32)# <35 ns 0+ 245.74 MeV
35Ca 35.00494(21)# 25.7(2) ms 1/2+# 263.12 MeV
36Ca 35.99309(4) 102(2) ms 0+ 281.44 MeV
37Ca 36.985870(24) 181.1(10) ms (3/2+) 296.96 MeV
38Ca 37.976318(5) 440(8) ms 0+ 313.42 MeV
39Ca 38.9707197(20) 859.6(14) ms 3/2+ 327.08 MeV
40Ca 39.96259098(22) STABLE 0+ 342.60 MeV
41Ca 40.96227806(26) 1.02(7)E+5 a 7/2- 350.67 MeV
42Ca 41.95861801(27) STABLE 0+ 362.47 MeV
43Ca 42.9587666(3) STABLE 7/2- 370.54 MeV
44Ca 43.9554818(4) STABLE 0+ 381.41 MeV
45Ca 44.9561866(4) 162.67(25) d 7/2- 388.55 MeV
46Ca 45.9536926(24) STABLE 0+ 399.41 MeV
47Ca 46.9545460(24) 4.536(3) d 7/2- 406.55 MeV
48Ca 47.952534(4) 43(38)E+18 a 0+ 416.49 MeV
49Ca 48.955674(4) 8.718(6) min 3/2- 421.76 MeV
50Ca 49.957519(10) 13.9(6) s 0+ 427.97 MeV
51Ca 50.9615(1) 10.0(8) s (3/2-)# 432.32 MeV
52Ca 51.96510(75) 4.6(3) s 0+ 436.66 MeV
53Ca 52.97005(54)# 90(15) ms 3/2-# 440.08 MeV
54Ca 53.97435(75)# 50# ms [>300 ns] 0+ 444.42 MeV
55Ca 54.98055(75)# 30# ms [>300 ns] 5/2-# 446.90 MeV
56Ca 55.98557(97)# 10# ms [>300 ns] 0+ 450.32 MeV
57Ca 56.99236(107)# 5# ms 5/2-# 451.87 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. 17

Réactions

Abondance

Terre - composés Source: carbonates/sulfates 19
Terre - Seawater: 412 mg/L 20
Terre -  Croûte:  41500 mg/kg = 4.15% 20
Terre -  Manteau:  2.1% 21
Terre -  lithosphère:  4.66% 22
Terre -  Hydrosphère:  0.05% 22
Terre -  Total:  1.54% 23
Planète Mercure) -  Total:  1.18% 23
Vénus -  Total:  1.61% 23
Univers -  Total:  0.007% 21
chondrites - Total: 4.9×104 (relative to 106 atoms of Si) 24
Corps humain - Total: 1.4% 25

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 4:7.
(2) - Zumdahl, Steven S. Chemistry, 4th ed.; Houghton Mifflin: Boston, 1997; p 883.
(3) - Gillespie, Ronald J., Eaton, Donald R., Humphreys, David A., and Robinson, Edward A. Atoms, Molecules, and Reactions; Prentice-Hall: Englewood Cliffs, NJ, 1994; p 604.
(4) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 930.
(5) - The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 13th ed.; Budavari, S.; O'Neil, M.J.; Smith, A.; Heckelman, P. E.; Kinneary, J. F., Eds.; Merck & Co.: Whitehouse Station, NJ, 2001; entry 1644.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(8) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(10) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(14) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(15) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(16) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(17) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
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(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 962.
(22) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 964.
(23) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(24) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
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