Krypton (36)

No - it's not about Superman at all...

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 characterized 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 meter, 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 colorless, odorless, 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.

•Name: Krypton
•Symbol: Kr
•Atomic number: 36
•Atomic weight: 83.798
•Standard state: gas at 298 K
•CAS Registry ID: 7439-90-9
•Group in periodic table: 18
•Group name: Noble gas
•Period in periodic table: 4
•Block in periodic table: p-block
•Color: colorless
•Classification: Non-metallic

Historical information

Krypton was discovered by Sir William Ramsay, Morris W. Travers at 1898 in Great Britain. Origin of name is from the Greek word "kryptos" meaning "hidden." 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.

Physical properties

•Melting point: 115.79 [or -157.36 °C (-251.25 °F)] K
•Boiling point: 119.93 [or -153.22 °C (-243.8 °F)] K
•Density of solid: 2155 kg m-3

Orbital properties

•Ground state electron configuration: [Ar].3d10.4s2.4p6
•Shell structure: 2.8.18.8
•Term symbol: 1S0

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.

Interesting Facts:

Krypton (English, French, German, Swedish) Cripto (Italian) Kriptón (Spanish)

•Krypton has 31 isotopes in all, out of which 5 are stable and the rest are radioactive.

•The half-life of radioactive krypton, 81Kr is 250,000 years.

•Krypton is produced in the Earth's crust as a result of radioactive decay of thorium and uranium.

•As most of the nuclear reactors are located in the northern hemisphere, the concentration of krypton at the north pole is about 30% higher than that at the south pole.

•The element Krypton is characterized by emission of sharp spectral lines, out of which, the green and yellow lines are the strongest and most prominent.

•When ionized, krypton gas emits bright white light, and hence krypton based bulbs are widely used in high speed photography. It is also used in slide and movie projectors.

•Krypton, like other inert gases, is used in making luminous, fluorescent lights used in different kinds of lamps, incandescent light bulbs, advertising signs, etc.

•One of the radioactive isotopes of krypton, can be combined with phosphorus to produce materials that glow or shine in the dark.

•Krypton-85, is used to study the flow of blood in the human body. When the gas is inhaled, it is absorbed by the blood and travels through the bloodstream and the heart along with blood. The pathway can be determined by holding a detection device over the person’s body.

•Krypton is used in the manufacture of quasi-homogeneous electromagnetic calorimeters, which are used to measure the quantity of heat.

•An interesting application of krypton gas was in defining a meter. Krypton-86, on heating gives off a clear bright line, which is reddish yellow in color. Between the period of 1960 and 1980, scientists defined meter as 1,650,763.73 times the width of this line produced by krypton.

•Krypton is considered to be one of the inert gases, which means it is chemically inactive. However, compounds of krypton have been synthesized in the laboratory and these synthetic compounds of krypton are used for research purpose