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About Krypton

Krypton Bohr

Krypton, atomic number 36, is one of the noble gases and is found in trace amounts (1 ppm) of the Earth’s atmosphere. The high cost of fractional distillation of liquefied air to isolate this element precludes widespread use in practical applications. When isolated, krypton is commercially used for high-speed photographic flash bulbs; and when mixed with other gases such as argon, is often present in fluorescent lamps. Krypton is mostly inert and few compounds containing krypton are known to exist. Krypton diflouride (KrF2) is one such compound – a volatile and colorless solid that can typically only be produced in amounts measured in grams.

When krypton is combined with fluorine, a host of industrial and scientific applications are made possible. Krypton fluoride lasers produce a deep-ultraviolet beam that is widely used in photolithography during the manufacturing process of semiconductor integrated circuits. Due to the short wavelength of its emitted light (λ = 248 nm), this type of laser is credited with significantly reducing piece-part spacing in microelectronic chips throughout the 1990s and 2000s. This increased the density of piece-parts on a microchip, transistors in a CPU for example, thereby increasing switching speed and lowering cost. For these reasons, the krypton fluoride laser has been credited as one of the key contributors in maintaining Moore’s Law during this time frame.

Sir William Ramsay, chemist and recipient of the 1904 Nobel Prize in Chemistry for his isolation of noble gases, along with Morris Travers, discovered krypton in 1898 by evaporating components of liquefied air. Six naturally occurring, stable isotopes of krypton have been discovered since. One such isotope, 81Kr, has been found useful in dating groundwater. 85Kr is a byproduct of uranium or plutonium fission and is itself radioactive with a half-life of 10.76 years. 86Kr, with the 605nm wavelength characteristic of its orange-red spectral line, was declared the official internationally-accepted definition of ‘meter’ as a unit of measure in 1960; replacing a metal bar, before being replaced itself in 1983 by the distance that light travels in a vacuum.

Krypton Properties

Krypton Bohr ModelKrypton is a Block P, Group 18, Period 4 element. The number of electrons in each of Krypton's shells is 2, 8, 18, 8 and its electronic configuration is [Ar] 3d10 4s2 4p6. In its elemental form krypton's CAS number is 7439-90-9. The krypton atom has a covalent radius of 116±4.pm and it's Van der Waals radius is 202.pm. Krypton has a concentration about 1 ppm in the atmosphere and can be extracted from liquid air. Krypton was discovered and first isolated by Sir William Ramsay and Morris W. Travers in 1898. The origin of the name Krypton comes from the Greek word kryptos meaning "hidden".

Krypton information, including technical data, properties, and other useful facts are specified below. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity, and thermal properties are included.


Symbol: Kr
Atomic Number: 36
Atomic Weight: 83.79
Element Category: noble gases
Group, Period, Block: 18, 4, p
Color: colorless
Other Names: Cripto
Melting Point: -157.36°C, -251.248°F, 115.79 K
Boiling Point: -153.415°C, -244.147°F, 119.735 K
Density: 3000 (85 K) kg·m3
Liquid Density @ Melting Point: 2.413 g·cm3
Density @ 20°C: 0.003708 g/cm3
Density of Solid: 2155 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: 115.775 K, 73.53 kPa
Critical Point: 209.48 K, 5.525 MPa
Heat of Fusion (kJ·mol-1): 1.64
Heat of Vaporization (kJ·mol-1): 9.05
Heat of Atomization (kJ·mol-1): 0
Thermal Conductivity: 9.43×10-3  W·m-1·K-1
Thermal Expansion: N/A
Electrical Resistivity: N/A
Tensile Strength: N/A
Molar Heat Capacity: 5R/2 = 20.786 J·mol-1·K-1
Young's Modulus: N/A
Shear Modulus: N/A
Bulk Modulus: N/A
Poisson Ratio: N/A
Mohs Hardness: N/A
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: (gas, 23 °C) 220, (liquid) 1120 m·s-1
Pauling Electronegativity: 3
Sanderson Electronegativity: 2.91
Allred Rochow Electronegativity: 2.94
Mulliken-Jaffe Electronegativity: 3.00 (12.5% s orbital)
Allen Electronegativity: 2.966
Pauling Electropositivity: 1
Reflectivity (%): N/A
Refractive Index: 1.000427
Electrons: 36
Protons: 36
Neutrons: 48
Electron Configuration: [Ar] 3d10 4s2 4p6
Atomic Radius: N/A
Atomic Radius,
non-bonded (Å):
2.02
Covalent Radius: 116±4 pm
Covalent Radius (Å): 1.16
Van der Waals Radius: 202 pm
Oxidation States: 2, 1, 0
Phase: Gas
Crystal Structure: cubic face-centered
Magnetic Ordering: diamagnetic
Electron Affinity (kJ·mol-1) Not stable
1st Ionization Energy: 1350.77 kJ·mol-1
2nd Ionization Energy: 2350.39 kJ·mol-1
3rd Ionization Energy: 3565.16 kJ·mol-1
CAS Number: 7439-90-9
EC Number: N/A
MDL Number: MFCD00151310
Beilstein Number: N/A
SMILES Identifier: [Kr]
InChI Identifier: InChI=1S/Kr
InChI Key: DNNSSWSSYDEUBZ-UHFFFAOYSA-N
PubChem CID: 5416
ChemSpider ID: 5223
Earth - Total: 0.0236E-8 cm^3/g
Mercury - Total: N/A
Venus - Total: 2.30E-8 cm^3/g
Earth - Seawater (Oceans), ppb by weight: 0.21
Earth - Seawater (Oceans), ppb by atoms: 0.016
Earth -  Crust (Crustal Rocks), ppb by weight: 0.15
Earth -  Crust (Crustal Rocks), ppb by atoms: 0.04
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: N/A
Meterorite (Carbonaceous), ppb by atoms: N/A
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 40
Universe, ppb by atom: 0.06
Discovered By: William Ramsay and Morris Travers
Discovery Date: 1898
First Isolation: William Ramsay and Morris Travers (1898)

Health, Safety & Transportation Information for Krypton

Krypton is not toxic and is chemically inert, and thus poses minimal environmental or health threats. At room temperature, krypton is typically only harmful when its presence leads to displacement of oxygen in the air, creating potential for asphyxiation.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Warning
Hazard Statements H280
Hazard Codes N/A
Risk Codes N/A
Safety Precautions N/A
RTECS Number N/A
Transport Information N/A
WGK Germany nwg
Globally Harmonized System of
Classification and Labelling (GHS)
Gas Cylinder - Gases Under Pressure

Krypton Isotopes

Naturally occurring krypton has six stable isotopes: 78Kr, 80Kr, 82Kr, 83Kr, 84Kr, and 86Kr.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
69Kr 68.96518(43)# 32(10) ms β+ to 69Br 5/2-# N/A 549.64 -
70Kr 69.95526(41)# 52(17) ms β+ to 70Br 0+ N/A 567.04 -
71Kr 70.94963(70) 100(3) ms β+ to 71Br; β+ + p to 70Se (5/2)- N/A 580.71 -
72Kr 71.942092(9) 17.16(18) s β+ to 72Br 0+ N/A 595.31 -
73Kr 72.939289(7) 28.6(6) s β+ to 73Br; β+ + p to 72Se 3/2- N/A 606.18 -
74Kr 73.9330844(22) 11.5 min EC to 74Br 0+ N/A 619.85 -
75Kr 74.930946(9) 4.3 min EC to 75Br 5/2+ N/A 630.72 -
76Kr 75.925910(4) 14.8 h EC to 76Br 0+ N/A 643.46 -
77Kr 76.9246700(21) 1.24 h EC to 77Br 5/2+ N/A 652.47 -
78Kr 77.9203648(12) Observationally Stable - 0+ N/A 664.28 0.35
79Kr 78.920082(4) 1.455 d EC to 79Br 1/2- N/A 672.35 -
80Kr 79.9163790(16) Stable - 0+ N/A 684.16 2.28
81Kr 80.9165920(21) 210000 y EC to 81Br 7/2+ N/A 692.24 -
82Kr 81.9134836(19) Stable - 0+ N/A 703.11 11.58
83Kr 82.914136(3) Stable - 9/2+ -0.970669 710.26 11.49
84Kr 83.911507(3) Stable - 0+ N/A 721.13 57
85Kr 84.9125273(21) 10.73 y β- to 85Rb 9/2+ 1.005 728.28 -
86Kr 85.91061073(11) Observationally Stable - 0+ N/A 738.22 17.3
87Kr 86.91335486(29) 1.27 h β- to 87Rb 5/2+ -1.018 743.51 -
88Kr 87.914447(14) 2.84 h β- to 88Rb 0+ N/A 750.65 -
89Kr 88.91763(6) 3.15 min β- to 89Rb 3/2(+#) N/A 755.94 -
90Kr 89.919517(20) 32.32(9) s β- to 90Rb 0+ N/A 762.15 -
91Kr 90.92345(6) 8.57(4) s β- to 91Rb 5/2(+) N/A 766.5 -
92Kr 91.926156(13) 1.840(8) s β- to 92Rb; β- + n to 91Rb 0+ N/A 771.79 -
93Kr 92.93127(11) 1.286(10) s β- to 93Rb; β- + n to 92Rb 1/2+ N/A 775.21 -
94Kr 93.93436(32)# 210(4) ms β- to 94Rb; β- + n to 93Rb 0+ N/A 780.49 -
95Kr 94.93984(43)# 114(3) ms β- to 95Rb 1/2(+) N/A 783.91 -
96Kr 95.94307(54)# 80(7) ms β- to 96Rb 0+ N/A 788.26 -
97Kr 96.94856(54)# 63(4) ms β- to 97Rb; β- + n to 96Rb 3/2+# N/A 791.69 -
98Kr 97.95191(64)# 46(8) ms Unknown 0+ N/A 796.97 -
99Kr 98.95760(64)# 40(11) ms Unknown (3/2+)# N/A 799.46 -
100Kr 99.96114(54)# 10# ms [>300 ns] Unknown 0+ N/A 803.81 -
100Kr 100 >635 ns β- + 2n to 99Rb; β- + n to 100Rb; β- to 101Rb; N/A N/A N/A -
Krypton Elemental Symbol

Recent Research & Development for Krypton

  • Youn-Sang Bae, Brad G. Hauser, Yamil J. Colón, Joseph T. Hupp, Omar K. Farha, Randall Q. Snurr, High xenon/krypton selectivity in a metal-organic framework with small pores and strong adsorption sites, Microporous and Mesoporous Materials, Volume 169, 15 March 2013
  • Dawid Gaszowski, Marek Ilczyszyn, Hydrogen bonding to xenon: A comparison with neon, argon and krypton complexes, Chemical Physics Letters, Volume 556, 29 January 2013
  • Yao Wang, Musab Abdul Razak, D.D. Do, Toshihide Horikawa, Kunimitsu Morishige, D. Nicholson, A computer simulation and experimental study of the difference between krypton adsorption on a graphite surface and in a graphitic hexagonal pore, Carbon, Volume 50, Issue 8, July 2012
  • B. Beeler, B. Good, S. Rashkeev, C. Deo, M. Baskes, M. Okuniewski, First-principles calculations of the stability and incorporation of helium, xenon and krypton in uranium, Journal of Nuclear Materials, Volume 425, Issues 1–3, June 2012
  • Xiaofeng Tian, Tao Gao, Gang Jiang, Duanwei He, Hongxing Xiao, The incorporation and solution of krypton in uranium dioxide: Density functional theory calculations, Computational Materials Science, Volume 54, March 2012
  • M. Gilbert, C. Davoisne, M. Stennett, N. Hyatt, N. Peng, C. Jeynes, W.E. Lee, Krypton and helium irradiation damage in neodymium–zirconolite, Journal of Nuclear Materials, Volume 416, Issues 1–2, 1 September 2011
  • C. Davoisne, M.C. Stennett, N.C. Hyatt, N. Peng, C. Jeynes, W.E. Lee, Krypton irradiation damage in Nd-doped zirconolite and perovskite, Journal of Nuclear Materials, Volume 415, Issue 1, 1 August 2011
  • Kathleen M. Krause, Matthias Thommes, Michael J. Brett, Pore analysis of obliquely deposited nanostructures by krypton gas adsorption at 87 K, Microporous and Mesoporous Materials, Volume 143, Issue 1, August 2011
  • H.S. Lee, Y.S. Lee, S.H. Seo, H.Y. Chang, The characteristics of the multi-hole RF capacitively coupled plasma discharged with neon, argon and krypton, Thin Solid Films, Volume 519, Issue 20, 1 August 2011
  • Michael Koerdt, Frank Vollertsen, Fabrication of an integrated optical Mach–Zehnder interferometer based on refractive index modification of polymethylmethacrylate by krypton fluoride excimer laser radiation, Applied Surface Science, Volume 257, Issue 12, 1 April 2011
  • J. Gan, D.D. Keiser Jr., B.D. Miller, D.M. Wachs, T.R. Allen, M. Kirk, J. Rest, Microstructure of RERTR DU-alloys irradiated with krypton ions up to 100 dpa, Journal of Nuclear Materials, Volume 411, Issues 1–3, April 2011
  • D. Zilli, P.R. Bonelli, C.J. Gommes, S. Blacher, J.-P. Pirard, A.L. Cukierman, Krypton adsorption as a suitable tool for surface characterization of multi-walled CNTs, Carbon, Volume 49, Issue 3, March 2011
  • A. Kaddouri, I. Ashraf, M. Ait El Fqih, H. Targaoui, A. El Boujlaïdi, K. Berrada, Photon emission from clean and oxygenated Si and SiO2 surfaces bombarded by 5 keV krypton ions, Applied Surface Science, Volume 256, Issue 1, 15 October 2009
  • Ilya Strashnov, Dave J. Blagburn, Jamie D. Gilmour, Hyperfine structure induced isotopic effects in krypton resonance ionization mass spectrometry, Optics Communications, Volume 282, Issue 17, 1 September 2009
  • S. Nsengiyumva, T.P. Ntsoane, A.T. Raji, M. Topíc, G. Kellermann, J.P. Rivière, D.T. Britton, M. Härting, The mutual influence of krypton implantation and pre-existing stress states in polycrystalline alpha titanium, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 267, Issue 16, 15 August 2009
  • M. Bregant, G. Cantatore, S. Carusotto, R. Cimino, F. Della Valle, G. Di Domenico, U. Gastaldi, M. Karuza, V. Lozza, E. Milotti, E. Polacco, G. Raiteri, G. Ruoso, E. Zavattini, G. Zavattini, Erratum to ‘Measurement of the Cotton–Mouton effect in krypton and xenon at 1064 nm with the PVLAS apparatus’ [Chem. Phys. Lett. 392 (2004) 276] and ‘A precise measurement of the Cotton–Mouton effect in neon’ [Chem. Phys. Lett. 410 (2005) 288], Chemical Physics Letters, Volume 477, Issues 4–6, 6 August 2009
  • Hsien-Hao Mei, Wei-Tou Ni, Sheng-Jui Chen, Sheau-shi Pan, (Q & A Collaboration), Measurement of the Cotton–Mouton effect in nitrogen, oxygen, carbon dioxide, argon, and krypton with the Q & A apparatus, Chemical Physics Letters, Volume 471, Issues 4–6, 26 March 2009
  • I. Strashnov, D.J. Blagburn, N. Thonnard, J.D. Gilmour, Tunable VUV light generation for resonance ionization mass spectrometry of Krypton, Optics Communications, Volume 282, Issue 5, 1 March 2009
  • K. Wittmaack, SIMS analysis of xenon and krypton in uranium dioxide: A comparison of two models of gas-phase ionisation, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 266, Issue 24, December 2008
  • J. Fedor, O. Echt, K. Gluch, S. Matt-Leubner, P. Scheier, T.D. Märk, On the role of the II(1/2g) state in spontaneous dissociation of krypton and xenon dimer ions, Chemical Physics Letters, Volume 437, Issues 4–6, 2 April 2007