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{{Element | name=Krypton| symbol=Kr | anumber=36 | amass=83.8 amu | noe=36 | class=Noble Gas | cstructure=Face-centered cubic | color=Colorless | date=1898 | discname= Sir [[William Ramsay]] and M. W. Travers | origname=From the Greek word ''kryptos'' (hidden) | uses=Lighting and scientific standards | obtained=Production of liquid air}}

{{Element | name=Krypton| symbol=Kr | anumber=36 | amass=83.8 amu | noe=36 | class=Noble Gas | cstructure=Face-centered cubic | density=.0037493 g/cm^3 | color=Colorless | stableisotopes=6 | date=1898 | discname= Sir [[William Ramsay]] and M. W. Travers | origname=From the Greek word ''kryptos'', hidden | uses=Lighting and scientific standards | obtained=Production of liquid air}}

'''Krypton''' is an [[element]] in the "[[noble gas]]" class (or "inert gas") of the [[periodic table of the elements|periodic table]].  It is colorless and odorless. It is almost (but not completely) chemically inert.  It has six stable isotopes.

'''Krypton''' is an [[element]] in the "[[noble gas]]" class (or "inert gas") of the [[periodic table of the elements|periodic table]].  It is colorless and odorless. It is almost (but not completely) chemically inert.  Its density as a gas (at standard temperature and pressure) is .0037493 g/cm^3, about 3 times that of air.  As a solid (below 116 degrees K) its density is 2.823 g/cm^3.

It is noteworthy in that one of its spectral lines is used as the official scientific definition of length—1 meter is 1650763.73 wavelengths.  (Prior to that, the meter was defined as the distance between two lines scratched on the "International Standard Meter stick".)

It is noteworthy in that, between 1960 and 1983, one of its spectral lines was used as the official scientific definition of length—1 meter was 1650763.73 wavelengths.  (Prior to that, the meter was defined as the distance between two lines scratched on the "International Standard Meter stick".  Since 1983, the unit of length has been defined in terms of time.)