SELEN

Wprowadzenie

Liczba atomowa: 34
Grupa: 16 or VI A
Masa atomowa: 78.96
Okres: 4
Numer CAS: 7782-49-2

Klasyfikacja

tlenowce
Fluorowiec
Gaz szlachetny
lantanowców
Actinoid
Rare Earth Element
Platinum Grupa Metal
Transuran
Brak stabilnego Izotopy
Solidny
Ciekły
Gaz
Solidny (przewidywane)

Opis • Zastosowania / Funkcja

Discovered by Berzelius in 1817, who found it associated with tellurium, named for the earth. Selenium is found in a few rare minerals,such as crooksite and clausthalite. In years past it has been obtained from flue dusts remaining from processing copper sulfide ores, but the anode mudsfrom electrolytic copper refineries now provide the source of most of the world’s selenium. Selenium is recovered by roasting the muds with soda orsulfuric acid, or by smelting them with soda and niter. Selenium exists in several allotropic forms. Three are generally recognized, but as many as sixhave been claimed. Selenium can be prepared with either an amorphous or crystalline structure. The color of amorphous selenium is either red, inpowder form, or black, in vitreous form. Crystalline monoclinic selenium is a deep red; crystalline hexagonal selenium, the most stable variety, is ametallic gray. Natural selenium contains six stable isotopes. Twenty four other isotopes and isomers have been characterized. The element is a memberof the sulfur family and resembles sulfur both in its various forms and in its compounds. Selenium exhibits both photovoltaic action, where light isconverted directly into electricity, and photoconductive action, where the electrical resistance decreases with increased illumination. These propertiesmake selenium useful in the production of photocells and exposure meters for photographic use, as well as solar cells. Selenium is also able to converta.c. electricity to d.c., and is extensively used in rectifiers. Below its melting point selenium is a p-type semiconductor and is finding many uses inelectronic and solid-state applications. It is used in Xerography for reproducing and copying documents, letters, etc. It is used by the glass industryto decolorize glass and to make ruby-colored glasses and enamels. It is also used as a photographic toner, and as an additive to stainless steel. Elementalselenium has been said to be practically nontoxic and is considered to be an essential trace element; however, hydrogen selenide and other seleniumcompounds are extremely toxic, and resemble arsenic in their physiological reactions. Hydrogen selenide in a concentration of 1.5 ppm is intolerableto man. Selenium occurs in some soils in amounts sufficient to produce serious effects on animals feeding on plants, such as locoweed, grown in suchsoils. Selenium is priced at about $150/kg. It is also available in high-purity form at a cost of about $250/kg (99.999%). 1

• "toxicity has long been known" 2
• "is known to be physiologically important (it is involved in the activity of vitamin E and certain enzymes)" 3
• "deficiency has been shown to be connected to the occurrence of congestive heart failure" 4
• "considered to be an antioxidant nutrient because it is present in enzymes that help protect against toxic species of oxygen and free radicals. Selenium deficiency is a major public health problem in certain parts of China, where it increases the risk of heart disease, bone and joint disorders, and liver cancer. Selenium is currently under intensive investigation as a possible protector against cancer." 5
• "used in photocopy machines and in solar cells." 6

Właściwości fizyczne

Form:7 vitreous
Temperatura topnienia:7*  180 °C = 453.15 K = 356 °F
Temperatura wrzenia:7* 685 °C = 958.15 K = 1265 °F
Punkt sublimacji:7 
Punkt potrójny:7 
Punkt krytyczny:7 1493 °C = 1766.15 K = 2719.4 °F 7
Form:7 gray
Temperatura topnienia:7*  220.5 °C = 493.65 K = 428.9 °F
Temperatura wrzenia:7* 685 °C = 958.15 K = 1265 °F
Punkt sublimacji:7 
Punkt potrójny:7 
Punkt krytyczny:7 1493 °C = 1766.15 K = 2719.4 °F 7
Gęstość:8  4.39 (alpha)/4.81 (gray)/4.28 (vitreous) g/cm3

* - at 1 atm

Konfiguracja elektronów

Konfiguracja elektronów: [Ar] 4s2 3d10 4p4
Blok: p
Najwyższy poziom energii Zajęte: 4
Elektrony walencyjne: 6

Liczby kwantowe:

n = 4
ℓ = 1
m = -1
ms = -½

klejenie

elektroujemność (Paulinga):9 2.55
Electropositivity (Paulinga): 1.45
powinowactwo elektronowe:10 2.020670 eV
utlenianie Zjednoczone: +4,-2,+6
Funkcja pracy:11 5.9 eV = 9.4518E-19 J

Potencjał jonizacyjny   eV 12  kJ/mol  
1 9.75238    941.0
2 21.19    2044.5
Potencjał jonizacyjny   eV 12  kJ/mol  
3 30.8204    2973.7
4 42.945    4143.6
Potencjał jonizacyjny   eV 12  kJ/mol  
5 68.3    6589.9
6 81.7    7882.8
7 155.4    14993.8

Termochemia

Ciepło właściwe: 0.321 J/g°C 13 = 25.346 J/mol°C = 0.077 cal/g°C = 6.058 cal/mol°C
Przewodność cieplna: 2.04 (W/m)/K, 27°C 14
Ciepło topnienia: 6.694 kJ/mol 15 = 84.8 J/g
Ciepło parowania: 37.7 kJ/mol 16 = 477.5 J/g
Stan skupienia Entalpia formacji (ΔHf°)17 Entropia (S°)17 Gibbs Free Energy (ΔGf°)17
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s hexagonal black) 0 0 10.144 42.442496 0 0
(g) 54.27 227.06568 42.21 176.60664 44.71 187.06664

izotopy

nuklidu Masa 18 Pół życia 18 spin jądrowy 18 Energia wiązania
65Se 64.96466(64)# <50 ms 3/2-# 531.57 MeV
66Se 65.95521(32)# 33(12) ms 0+ 548.02 MeV
67Se 66.95009(21)# 133(11) ms 5/2-# 560.75 MeV
68Se 67.94180(4) 35.5(7) s 0+ 577.21 MeV
69Se 68.93956(4) 27.4(2) s (1/2-) 587.14 MeV
70Se 69.93339(7) 41.1(3) min 0+ 600.80 MeV
71Se 70.93224(3) 4.74(5) min 5/2- 609.80 MeV
72Se 71.927112(13) 8.40(8) d 0+ 622.53 MeV
73Se 72.926765(11) 7.15(8) h 9/2+ 631.54 MeV
74Se 73.9224764(18) STABILNY 0+ 643.33 MeV
75Se 74.9225234(18) 119.779(4) d 5/2+ 651.40 MeV
76Se 75.9192136(18) STABILNY 0+ 662.27 MeV
77Se 76.9199140(18) STABILNY 1/2- 670.34 MeV
78Se 77.9173091(18) STABILNY 0+ 680.28 MeV
79Se 78.9184991(18) 2.95(38)E+5 a 7/2+ 687.42 MeV
80Se 79.9165213(21) STABILNY 0+ 697.35 MeV
81Se 80.9179925(22) 18.45(12) min 1/2- 704.49 MeV
82Se 81.9166994(22) 97(5)E+18 a 0+ 713.49 MeV
83Se 82.919118(4) 22.3(3) min 9/2+ 718.77 MeV
84Se 83.918462(16) 3.1(1) min 0+ 727.77 MeV
85Se 84.92225(3) 31.7(9) s (5/2+)# 732.12 MeV
86Se 85.924272(17) 15.3(9) s 0+ 738.33 MeV
87Se 86.92852(4) 5.50(12) s (5/2+)# 742.67 MeV
88Se 87.93142(5) 1.53(6) s 0+ 747.95 MeV
89Se 88.93645(32)# 0.41(4) s (5/2+)# 751.36 MeV
90Se 89.93996(43)# 300# ms [>300 ns] 0+ 756.64 MeV
91Se 90.94596(54)# 270(50) ms 1/2+# 759.12 MeV
92Se 91.94992(64)# 100# ms [>300 ns] 0+ 763.47 MeV
93Se 92.95629(86)# 50# ms [>300 ns] 1/2+# 765.02 MeV
94Se 93.96049(86)# 20# ms [>300 ns] 0+ 769.36 MeV
Wartości oznaczone # nie jest całkowicie pochodzą z danych doświadczalnych, ale przynajmniej częściowo z systematycznej tendencji. Obraca się słabe argumenty przypisania są w nawiasach. 18

reakcje

Obfitość

Ziemia - Związki źródłowe: sulfides 19
Ziemia - Woda morska: 0.0002 mg/L 20
Ziemia -  Skorupa:  0.05 mg/kg = 0.000005% 20
Ziemia -  Całkowity:  9.6 ppm 21
Merkury) -  Całkowity:  0.79 ppm 21
Wenus -  Całkowity:  5.4 ppm 21
chondrytach - Całkowity: 19 (relative to 106 atoms of Si) 22

związki

Informacje dotyczące bezpieczeństwa


Karta Charakterystyki - ACI Alloys, Inc.

Po więcej informacji

Linki zewnętrzne:

źródła

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:28.
(2) - Zumdahl, Steven S. Chemistry, 4th ed.: Houghton Mifflin: Boston, 1997; p 916.
(3) - Zumdahl, Steven S. Chemistry, 4th ed.: Houghton Mifflin: Boston, 1997; p 916.
(4) - Zumdahl, Steven S. Chemistry, 4th ed.: Houghton Mifflin: Boston, 1997; p 916.
(5) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 927.
(6) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 953.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(9) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(11) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(14) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(15) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(16) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(17) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(18) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(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) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(22) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.