CÉSIUM

introduction

Numéro atomique: 55
Groupe: 1 or I A
Poids atomique: 132.90545
Période: 6
Numero CAS: 7440-46-2

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

Cesium was discovered spectroscopically by Bunsen and Kirchhoff in 1860 in mineral water from Durkheim. Cesium, an alkali metal, occurs in lepidolite,pollucite (a hydrated silicate of aluminum and cesium), and in other sources. One of the world’s richest sources of cesium is located at Bernic Lake,Manitoba. The deposits are estimated to contain 300,000 tons of pollucite, averaging 20% cesium. It can be isolated by electrolysis of the fused cyanideand by a number of other methods. Very pure, gas-free cesium can be prepared by thermal decomposition of cesium azide. The metal is characterizedby a spectrum containing two bright lines in the blue along with several others in the red, yellow, and green. It is silvery white, soft, and ductile. Itis the most electropositive and most alkaline element. Cesium, gallium, and mercury are the only three metals that are liquid at room temperature.Cesium reacts explosively with cold water, and reacts with ice at temperatures above –116°C. Cesium hydroxide, the strongest base known, attacksglass. Because of its great affinity for oxygen the metal is used as a “getter” in electron tubes. It is also used in photoelectric cells, as well as a catalystin the hydrogenation of certain organic compounds. The metal has recently found application in ion propulsion systems. Cesium is used in atomicclocks, which are accurate to 5 s in 300 years. Its chief compounds are the chloride and the nitrate. Cesium has 52 isotopes and isomers with massesranging from 112 to 148. The present price of cesium is about $40/g (99.98%). 1

• "used in some photoelectric cells" 2

Propriétés physiques

Point de fusion:3*  28.5 °C = 301.65 K = 83.3 °F
Point d'ébullition:3* 671 °C = 944.15 K = 1239.8 °F
sublimation point:3 
Triple point:3 
Point critique:3 1665 °C = 1938.15 K = 3029 °F 3
Densité:4  1.93 g/cm3

* - at 1 atm

Configuration de l'électron

Configuration de l'électron: [Xe] 6s1
Bloque: s
Plus haut niveau d'énergie occupés: 6
Électrons de valence: 1

Nombres quantiques:

n = 6
ℓ = 0
m = 0
ms = +½

Bonding

Électronégativité (échelle de Pauling):5 0.79
Electropositivity (échelle de Pauling): 3.21
Electron Affinity:6 0.471626 eV
oxydation États: +1
Fonction de travail:7 1.90 eV = 3.0438E-19 J

ionisation potentiel   eV 8  kJ/mol  
ionisation potentiel   eV 8  kJ/mol  
1 3.8939    375.7
ionisation potentiel   eV 8  kJ/mol  
2 23.15745    2234.4

Thermochimie

Chaleur spécifique: 0.242 J/g°C 9 = 32.163 J/mol°C = 0.058 cal/g°C = 7.687 cal/mol°C
Conductivité thermique: 59 (W/m)/K, 27°C 10
Température de fusion: 2.092 kJ/mol 11 = 15.7 J/g
Chaleur de vaporisation: 67.74 kJ/mol 12 = 509.7 J/g
État de la matière Enthalpie de formation (ΔHf°)13 Entropy (S°)13 Gibbs Free Energy (ΔGf°)13
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(g) 56 234.304 50.30 210.4552 44 184.096
(s) 0 0 20.35 85.1444 0 0
(ℓ) 0.499 2.087816 22.01 92.08984 0.006 0.025104
(g) 18.3 76.5672 41.94 175.47696 11.9 49.7896

isotopes

Nuclide Masse 14 Demi vie 14 Spin nucléaire 14 Énergie de liaison
112Cs 111.95030(33)# 500(100) μs 1+# 907.53 MeV
113Cs 112.94449(11) 16.7(7) μs 5/2+# 924.92 MeV
114Cs 113.94145(33)# 0.57(2) s (1+) 932.99 MeV
115Cs 114.93591(32)# 1.4(8) s 9/2+# 950.38 MeV
116Cs 115.93337(11)# 0.70(4) s (1+) 958.45 MeV
117Cs 116.92867(7) 8.4(6) s (9/2+)# 975.83 MeV
118Cs 117.926559(14) 14(2) s 2 983.90 MeV
119Cs 118.922377(15) 43.0(2) s 9/2+ 991.98 MeV
120Cs 119.920677(11) 61.2(18) s 2(-#) 1,000.05 MeV
121Cs 120.917229(15) 155(4) s 3/2(+) 1,017.43 MeV
122Cs 121.91611(3) 21.18(19) s 1+ 1,025.50 MeV
123Cs 122.912996(13) 5.88(3) min 1/2+ 1,033.58 MeV
124Cs 123.912258(9) 30.9(4) s 1+ 1,041.65 MeV
125Cs 124.909728(8) 46.7(1) min 1/2(+) 1,059.03 MeV
126Cs 125.909452(13) 1.64(2) min 1+ 1,067.10 MeV
127Cs 126.907418(6) 6.25(10) h 1/2+ 1,075.18 MeV
128Cs 127.907749(6) 3.640(14) min 1+ 1,083.25 MeV
129Cs 128.906064(5) 32.06(6) h 1/2+ 1,091.32 MeV
130Cs 129.906709(9) 29.21(4) min 1+ 1,099.39 MeV
131Cs 130.905464(5) 9.689(16) d 5/2+ 1,107.46 MeV
132Cs 131.9064343(20) 6.480(6) d 2+ 1,115.53 MeV
133Cs 132.905451933(24) STABLE 7/2+ 1,123.60 MeV
134Cs 133.906718475(28) 2.0652(4) a 4+ 1,131.68 MeV
135Cs 134.9059770(11) 2.3(3)E+6 a 7/2+ 1,139.75 MeV
136Cs 135.9073116(20) 13.16(3) d 5+ 1,147.82 MeV
137Cs 136.9070895(5) 30.1671(13) a 7/2+ 1,155.89 MeV
138Cs 137.911017(10) 33.41(18) min 3- 1,154.65 MeV
139Cs 138.913364(3) 9.27(5) min 7/2+ 1,162.72 MeV
140Cs 139.917282(9) 63.7(3) s 1- 1,170.79 MeV
141Cs 140.920046(11) 24.84(16) s 7/2+ 1,169.54 MeV
142Cs 141.924299(11) 1.689(11) s 0- 1,177.62 MeV
143Cs 142.927352(25) 1.791(7) s 3/2+ 1,185.69 MeV
144Cs 143.932077(28) 994(4) ms 1(-#) 1,184.44 MeV
145Cs 144.935526(12) 582(6) ms 3/2+ 1,192.51 MeV
146Cs 145.94029(8) 0.321(2) s 1- 1,191.27 MeV
147Cs 146.94416(6) 0.235(3) s (3/2+) 1,199.34 MeV
148Cs 147.94922(62) 146(6) ms 1,207.41 MeV
149Cs 148.95293(21)# 150# ms [>50 ms] 3/2+# 1,206.17 MeV
150Cs 149.95817(32)# 100# ms [>50 ms] 1,214.24 MeV
151Cs 150.96219(54)# 60# ms [>50 ms] 3/2+# 1,213.00 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. 14

Abondance

Terre - composés Source: halide salts and brines 15
Terre - Seawater: 0.0003 mg/L 16
Terre -  Croûte:  3 mg/kg = 0.0003% 16
Terre -  Total:  15.3 ppb 17
Planète Mercure) -  Total:  2.5 ppb 17
Vénus -  Total:  17.0 ppb 17
chondrites - Total: 0.14 (relative to 106 atoms of Si) 18
Corps humain - Total: 0.000002% 19

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 4:8.
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 928.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(5) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(7) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(13) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(14) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(15) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(16) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(17) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(18) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(19) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.