Krypton: the essentials
Krypton is present in the air at about 1 ppm. The atmosphere of Mars contains a little (about 0.3 ppm) of krypton. It is characterised by its brilliant green and orange spectral lines. The spectral lines of krypton are easily produced and some are very sharp. In 1960 it was internationally agreed that the fundamental unit of length, the metre, should be defined as 1 m = 1,650,763.73 wavelengths (in vacuo) of the orange-red line of Kr-33.
Under normal conditions krypton is colourless, odourless, fairly expensive gas. Solid krypton is a white crystalline substance with a face-centered cubic structure which is common to all the "rare gases". Krypton difluoride, KrF2, has been prepared in gram quantities and can be made by several methods.
Image adapted with permission from Prof James Marshall's (U. North Texas, USA) Walking Tour of the elements CD.
Krypton: historical information
Krypton was discovered in 1898 by Sir William Ramsay and his student Morris Travers in the residue left after liquid air had nearly boiled away. Krypton was left in the residue after boiling away water, oxygen, nitrogen, helium, and argon from the sample of air. Krypton is present in the air at about 1 ppm. Neon was discovered by a similar procedure by the same workers just a few weeks later.
Krypton around us Read more »
Krypton has no biological role.
Krypton is present in the air to the extent of about 1 ppm. The atmosphere of Mars contains a little krypton (about 0.3 ppm).
|Location||ppb by weight||ppb by atoms||Links|
|Human||(no data) ppb by weight||(no data) atoms relative to C = 1000000|
Physical properties Read more »
Heat properties Read more »
- Melting point: 115.79 [‑157.36 °C (‑251.25 °F)] K
- Boiling point: 119.93 [‑153.22 °C (‑243.8 °F)] K
- Enthalpy of fusion: |203| kJ mol-1
Crystal structure Read more »
The solid state structure of krypton is: ccp (cubic close-packed).
Krypton: orbital properties Read more »
Krypton atoms have 36 electrons and the shell structure is 18.104.22.168. The ground state electronic configuration of neutral Krypton is [Ar].3d10.4s2.4p6 and the term symbol of Krypton is 1S0.
- Pauling electronegativity: 3.00 (Pauling units)
- First ionisation energy: 1350.8 kJ mol‑1
- Second ionisation energy: 2350.4 kJ mol‑1
Isolation: krypton is present to a small extent (about 1 ppm by volume) in the atmosphere and is obtained as a byproduct from the liquefaction and separation of air. This would not normally be carried out in the laboratory and krypton is available commercially in cylinders at high pressure.
Krypton isotopes Read more »
Krypton isotopes are used in various medical and scientific applications. Kr-82 is used for the production of Rb-81/Kr-81m generators. Many of the stable isotopes of Krypton are used in the study of the pulmonary system. Kr-78 can be used for the production of Br-75 although production of Br-75 via Se-76 is more common. Kr-86 has been used to define the standard measure of length: 1 meter is exactly 1,650,763.73 wavelengths of this isotope.
|78Kr||77.920396 (9)||0.35 (1)||0|
|80Kr||79.916380 (9)||2.28 (6)||0|
|82Kr||81.913482 (6)||11.58 (14)||0|
|83Kr||82.914135 (4)||11.49 (6)||9/2||-0.970669|
|84Kr||83.911507 (4)||57.00 (4)||0|
|86Kr||85.910616 (5)||17.30 (22)||0|