Krypton

General:

Name:Krypton Symbol:Kr
Type:Noble Gas Atomic weight:83.80
Density @ 293 K: 0.003708 g/cm3 Atomic volume:38.9 cm3/mol
Discovered:

William Ramsay and Morris Travers discovered krypton in 1898. They discovered it in the residue remaining after liquid air had been fractionally distilled. With the oxygen and nitrogen gone, a bright yellow spectral line that was neither sodium nor helium revealed the presence of a new element. The element name comes from the Greek word 'kryptos', meaning hidden.

States

State (s, l, g):gas
Melting point:115.9 K (-157.3 °C) Boiling point:119.4 K (-153.2 °C)

Energies

Specific heat capacity:0.248 J g-1 K-1 Heat of atomization:0 kJ mol-1
Heat of fusion: 1.638 kJ mol-1 Heat of vaporization :9.029 kJ mol-1
1st ionization energy:1350.7 kJ mol-1 2nd ionization energy:2350.3 kJ mol-1
3rd ionization energy:3565.1 kJ mol-1 Electron affinity:kJ mol-1

Oxidation & Electrons

Shells:2,8,18,8 Electron configuration:[Ar] 3d10 4s2 4p6
Minimum oxidation number:0 Maximum oxidation number:2
Min. common oxidation no.:0 Max. common oxidation no.:2
Electronegativity (Pauling Scale): 3 Polarizability volume:2.5 Å3

Appearance & Characteristics

Structure:fcc: face-centered cubic Color:Colorless
Hardness:mohs
Harmful effects:

Krypton is considered to be non-toxic.

Characteristics:

Krypton is a colorless, odorless, inert gas.

Although it is extremely unreactive krypton can react with fluorine, and a few compounds of the element have been prepared, including krypton (II) fluoride and krypton clathrates.

Solid krypton is white and crystalline.


Uses:

Krypton is used in lighting products. Ionized krypton gas appears whitish - see photo on left - which makes krypton-based bulbs useful as a brilliant white light source in high speed photography. An important lighting use is also in high-powered, flashing airport runway lights.

Krypton is employed alongside other gases to make luminous 'neon light' style signs that glow with a greenish-yellow light.

It is used as a filling gas for energy saving fluorescent lights and as an inert filling gas in incandescent bulbs.

Between 1960 and 1980, an international agreement defined the meter length in terms of the wavelength of light emitted from the krypton isotope, 86Kr. (The meter is now defined as the distance traveled by light in vacuum during a time of 1/299,792,458 of a second. The time is measured using a cesium atomic clock.)

Reactions

Reaction with air:none Reaction with 6 M HCl:none
Reaction with 15 M HNO3:none Reaction with 6 M NaOH:none

Compounds

Oxide(s):none Chloride(s):none
Hydride(s):none

Radius

Atomic radius:88 pm Ionic radius (1+ ion):pm
Ionic radius (2+ ion):pm Ionic radius (3+ ion):pm
Ionic radius (2- ion):pm Ionic radius (1- ion):pm

Conductivity

Thermal conductivity:0.01 W m-1 K-1 Electrical conductivity:S cm-1

Abundance & Isotopes

Abundance earth's crust: 100 parts per trillion by weight, 30 parts per trillion by moles
Abundance solar system:parts per million by weight, parts per million by moles
Cost, pure:$33 per 100g
Cost, bulk:$ per 100g
Source:

Krypton is obtained commercially by fractional distillation of liquid air.

Isotopes:

Krypton has 25 isotopes whose half-lives are known, with mass numbers 71 to 95. Of these, six are stable: 78Kr, 80Kr, 82Kr, 83Kr, 84Kr and 86Kr. The most abundant isotope is 84Kr at 57.03%.

Other

Other:

 

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