We use cookies and other tracking technologies to improve your browsing experience on our website, to show you personalized content and targeted ads, to analyze our website traffic, and to understand where our visitors are coming from. For more information, please review our cookie policy and privacy policy.
By choosing I Accept, you consent to our use of cookies and other tracking technologies.

Krypton (Kr)

Krypton is a chemical element of the periodic table with chemical symbol Kr and atomic number 36 with an atomic weight of 83.7982 u and is classed as noble gas and is part of group 18 (noble gases). Krypton is gas at room temperature.

Krypton in the periodic table

Atomic number36
Group18 (Noble gases)
ClassificationNoble Gas
AppearanceColorless gas, exhibiting a whitish glow in a high electric field
Color Colorless
Number of protons36 p+
Number of neutrons48 n0
Number of electrons36 e-
From Wikipedia, the free encyclopediaKrypton (from Greek:κρυπτός kryptos "the hidden one") is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionally distilling liquefied air, and is often used with other rare gases in fluorescent lamps.

Physical properties

Phase at STPGas
Density3.749 g/cm3
Atomic weight83.7982 u

Thermal properties

Melting point115.78 K
-157.37 °C
-251.266 °F
Boiling point119.93 K
-153.22 °C
-243.796 °F
Heat of vaporization9.029 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)3
Electron affinity-96 kJ/mol
Oxidation states0, +1, +2
(rarely more than 0; oxide is unknown)
Ionization energies
  1. 1350.8 kJ/mol
  2. 2350.4 kJ/mol
  3. 3565 kJ/mol
  4. 5070 kJ/mol
  5. 6240 kJ/mol
  6. 7570 kJ/mol
  7. 10710 kJ/mol
  8. 12138 kJ/mol
  9. 22274 kJ/mol
  10. 25880 kJ/mol
  11. 29700 kJ/mol
  12. 33800 kJ/mol
  13. 37700 kJ/mol
  14. 43100 kJ/mol
  15. 47500 kJ/mol
  16. 52200 kJ/mol
  17. 57100 kJ/mol
  18. 61800 kJ/mol
  19. 75800 kJ/mol
  20. 80400 kJ/mol
  21. 85300 kJ/mol
  22. 90400 kJ/mol
  23. 96300 kJ/mol
  24. 101400 kJ/mol
  25. 111100 kJ/mol
  26. 116290 kJ/mol
  27. 282500 kJ/mol
  28. 296200 kJ/mol
  29. 311400 kJ/mol
  30. 326200 kJ/mol

Electron configuration for krypton

Electron configuration
Shorthand configuration
[Ar] 3d10 4s2 4p6
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6
Electron configuration chart
Electrons per shell2, 8, 18, 8
Valence electrons 8
Valency electrons 0
Bohr model
KryptonElectron shell for Krypton, created by Injosoft ABKr
Figure: Shell diagram of Krypton (Kr) atom.
Orbital Diagram

The history of Krypton

Discovery and first isolationWilliam Ramsay, Morris Travers (1898)
Discovery of krypton
Krypton was discovered in Britain in 1898 by William Ramsay, a Scottish chemist, and Morris Travers, an English chemist, in residue left from evaporating nearly all components of liquid air. Neon was discovered by a similar procedure by the same workers just a few weeks later. William Ramsay was awarded the 1904 Nobel Prize in Chemistry for discovery of a series of noble gases, including krypton.


List of unique identifiers for Krypton in various chemical registry databases
CAS Number7439-90-9
ChemSpider ID5223
EC number231-098-5
PubChem CID Number5416