Structural Formula Vector Image
Title: Krypton
CAS Registry Number: 7439-90-9
Literature References: Kr; at. wt 83.798; at. no. 36. Group VIIIA (18), also known as Group 0. A noble gas characterized by an electronic structure in which the outer p subshell is entirely filled. Naturally occurring stable isotopes (mass numbers): 78 (0.35%); 80 (2.25%); 82 (11.6%); 83 (11.5%); 84 (57.0%); 86 (17.3%); known artificial radioactive isotopes: 71-77; 79; 81; 85; 87-95; 97. Isoln from the final residues obtained after evaporation of liq air: Ramsay, Travers, Proc. Roy. Soc. 63 [A], 405 (1898). Concentration in air: 1.14 ppm by vol. Obtained commercially from the atmosphere by distillation-liquefaction process. Prepn: Lepape, Compt. Rend. 187, 231 (1928); Claude, ibid. 581. Monograph: Argon, Helium and the Rare Gases vols. 1, 2, G. A. Cook, Ed. (Interscience, New York, 1963) 818 pp. Diagnostic use of 81mKr in lung ventilation imaging: A. Zwijnenburg et al., Clin. Phys. Physiol. Meas. 9, 147 (1988). Reviews: A. H. Cockett, K. C. Smith, "The Monatomic Gases" in Comprehensive Inorganic Chemistry vol. 1, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 139-211; N. Bartlett, F. O. Sladky, "The Chemistry of Krypton, Xenon and Radon" ibid. pp 213-249; S.-C. Hwang, W. R. Weltmer, Jr. in Kirk-Othmer Encyclopedia of Chemical Technology vol. 13 (John Wiley & Sons, 4th ed., 1995) pp 1-38; G. J. Schrobilgen, J. M. Whalen, ibid. pp 38-53; Chemistry of the Elements, N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 1042-1059.
Properties: Colorless, odorless, inert, monatomic gas; will form compds with highly electronegative elements such as O, F, Cl. Condenses to a colorless liquid. Triple pt temp 115.95 K, press 73.15 kPa. Critical temp 209.4 K, critical press 5502 kPa, critical d 908 kg/m3. Gas: d0 (101.3 kPa) 3.7493 kg/m3, d (normal bp) 8.6 kg/m3. Liquid: normal bp -153.35°, d (normal bp) 2415 kg/m3, d (triple pt) 2451 kg/m3, heat of vaporization (normal bp) 9.050 kJ/mol. Solid: d (triple pt) 2826 kg/m3, heat of vaporization (triple pt) 10.77 kJ/mol, heat of fusion (triple pt) 1.64 kJ/mol; solid form exists as face-centered cubic crystals at normal pressure. Excitation potentials: 9.91; 10.03; 10.56; 10.64 ev; ionization potentials: 14.00; 14.66 ev: Brocklehurst, Q. Rev. Chem. Soc. 22, 147 (1968). Soly of gas in water (20°): 59.4 cm3/kg water. Slightly soluble in water with formation of a hydrate; ideal formula Kr.5.75H2O. A hexadeuterate has been prepd. Soluble in liquid oxygen. Emission spectra: T. Jacksier, R. M. Barnes, Appl. Spectrosc. 48, 65 (1994).
Boiling point: bp -153.35°
Density: d 908 kg/m3; d0 (101.3 kPa) 3.7493 kg/m3; d (normal bp) 8.6 kg/m3; d (normal bp) 2415 kg/m3; d (triple pt) 2451 kg/m3; d (triple pt) 2826 kg/m3
Derivative Type: Krypton difluoride
CAS Registry Number: 13773-81-4
Molecular Formula: F2Kr
Molecular Weight: 121.79
Percent Composition: F 31.20%, Kr 68.81%
Literature References: Prepn: Turner, Pimentel, Science 140, 974 (1963).
Properties: Colorless solid; decomposes rapidly at room temperature. d (calc) 3.24. Vapor pressure (mm Hg): 10 ±1 at -15.5°; 29 ±2 at 0°; 73 ±3 at 15°.
Density: d (calc) 3.24
CAUTION: Can act as a simple asphyxiant by displacing air. See: Matheson Gas Data Book (Matheson Co., Inc., 4th ed., East Rutherford, NJ, 1966) pp 313-314.
Use: As gas filler in special purpose electric bulbs. To initiate and sustain the arc in metal-vapor discharge tubes, such as mercury and sodium vapor lamps. To determine surface areas of fine solids by adsorption techniques.
Therap-Cat: 81mKr as diagnostic aid (radioactive imaging agent).

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