Krypton

Krypton
General Info
Atomic Symbol	Atomic symbol::Kr
Atomic Number	Atomic number::36
Atomic Weight	Atomic weight::83.798 g/mol
Chemical series	Noble gases
Appearance	colorless
Group, Period, Block	18, 4, p
Electron configuration	[Ar] 4s2 3d10 4p6
Electrons per shell	2, 8, 18, 8
CAS number	CAS number::7439-90-9
Physical properties
Phase	gas
Density	Density::0.003733 g/ml
Melting point	Melting point::115.79 K
Boiling point	Boiling point::119.93 K
Isotopes of Krypton
iso NA half-life DT DE (MeV) DP 78Kr 0.35% 2.3x1020 y ε ε - 78Se 79Kr 35.04 h syn ε - 79Br 79Kr 35.04 h syn β+ 0.604 79Br 79Kr 35.04 h syn γ 0.26, 0.39, 0.60 - 80Kr 2.25% 80Kr is stable with 44 neutrons. 81Kr syn 2.29x105 y ε - 81Br 81Kr syn 2.29x105 y γ 0.281 - 82Kr 11.6% 82Kr is stable with 46 neutrons. 83Kr 11.5% 83Kr is stable with 47 neutrons. 84Kr 57% 84Kr is stable with 48 neutrons. 85Kr syn 10.756 y β- 0.687 85Rb 86Kr 17.3% 86Kr is stable with 50 neutrons.
All properties are for STP unless otherwise stated.

Krypton is a chemical element with an atomic number of 26. In the Periodic Table, it can be found in Period 4 and Group 18 (the noble gases). It is perhaps best known as forming the substance that made Superman weak, but there is no need to worry about Krypton being harmful to your health. There is no evidence that Krypton is dangerous to people, plants, or animals [1].

Its name comes from the Greek word "Kryptos", meaning hidden [2]. Krypton wasn't discovered until 1898 by Sir William Ramsay and Morris M. Travers, a Scottish and English chemist. While studying liquefied air, they discovered traces of liquid krypton. Krypton had remained after boiling away most the other more volatile parts of air [3].

Properties

Like all noble gases, Krypton lacks color, taste, and scent (Jones 131). Krypton is part of the group VIIA elements, also known as the noble gases. The noble gases all have full valence shells and therefore rarely bond or react with others (Jones, 131). They are the only group to have an oxidation number of 0. They were first known as the inert gases because of how unreactive they are. Compounds of Krypton can be synthetically created, but do not normally appear in nature [4].

Occurrences

Krypton is present in the earth's atmosphere, but only barely at 1 ppm [5]. That means our atmosphere is made up of 0.0001% Krypton [6]. It has also been found that the atmosphere of Mars contains 0.3 ppm of Krypton [7]

Before, Krypton was believed not to bond to other atoms, but now we know it forms a few compounds; the most common and easiest to form being Krypton difluoride (KrF₂) [8].

Uses

Krypton filled discharge tube shaped like the atomic symbol.

Krypton is a byproduct of the separation of liquefied air [9]. Because so little of it is present in our atmosphere the cost of Krypton is very high and therefore has little practical commercial use. The current price is about $30/liter [10].

Krypton, along with other noble gases, is able to emit light when it is electrically charged. [11] Therefore, Krypton is used in certain fluorescent light bulbs. When mixed with other gases, such as argon it creates a yellow-greenish color that is used in lamps and signs[12].

A Krypton-fluorine excimer, is also used in UV-lasers for eye surgery [13].

It is used in high speed photography for photographic flashes.

In the 1960s an international agreement was made that temporarily used the light of an isotope of Krypton, Kr-86, for the measurement of a meter [14]. Previously, the measurement had been one/ten-millionth of the distance between the equator and the north pole through a meridian in Paris [15]. Krypton-86 is naturally occurring, nonradioactive isotope. A spectral line of Krypton-86 measures at 1,650,762.73 wavelengths. It was used as the definition of a meter until October 1983 when it was changed by the International Bureau of Weights and Measures [16].

Kryptonite and Superman

Superman: invincible except when it comes to kryptonite

Superman is a well known super hero known for his x-ray vision, incredible hearing and superhuman strength. He was an unborn baby on the planet Krypton, before chaos occurred. Jor-El, his father, knew that their planet was about to be destroyed, so he placed Kal-El on a spacecraft in hopes of saving him[17].

Kal-el landed on the planet earth and was born in Smallville, Kansas. Jonathan and Martha Kent found the baby, brought him back home, gave him the name Clark Kent and raised him for the rest of his life. As Clark grew up he began to develop his superhuman powers[18]. Clark's power comes from the yellow earth sun and his ability to store energy from the sun in his cells [19].

Superman's only weak spot is his vulnerability to Kryptonite. Kryptonite is a green substance that comes from his home planet of Krypton. Whenever Superman is exposed to Kryptonite he becomes weak, and after long exposure he dies. Krypton causes Superman to become weak because it interferes with Clark's cells and his ability to draw power from the yellow sun [20].

References

• Krypton Jefferson Lab, Steve Gagnon.
• Krypton: The Essentials WebElements, Mark Winter
• Krypton Chemicool
• Properties, Applications and Uses of the "Rare Gases" Neon, Krypton and Xenon Universal Industrial Gases
• Krypton by C.R. Hammond. CRC Handbook of Chemistry and Physics, 1913-1995. David R. Lide, Editor in Chief.
• Krypton Isotopes chemical-elements.info, 2007.
• Krypton Chemical Element.
• Superman Biography, History Supermanherostuff.com DC Who's Who In The DC Universe, August 1990, Published Monthly By DC Comics Inc.
• How Kryptonite Works by Tracy V. Wilson. How Stuff Works.
• The Elements