Krypton
| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Krypton, Kr | ||||
| Appearance |
Colorless gas Exhibits a whitish glow in a high electric field | ||||
| Krypton in the periodic table | |||||
| |||||
| Atomic number | 36 | ||||
| Standard atomic weight (Ar) | |||||
| Group, block | 18; p-block | ||||
| Period | period 4 | ||||
| Electron configuration | [Ar] 3d10 4s2 4p6 | ||||
per shell | 2, 8, 18, 8 | ||||
| Physical properties | |||||
| Colorless | |||||
| Phase | Gas | ||||
| Melting point | 115.78 K (−157.37 °C, −251.27 °F) | ||||
| Boiling point | 119.93 K (−153.415 °C, −244.147 °F) | ||||
| Density at (0 °C and 101.325 kPa) | 3.749 g/L | ||||
| when liquid, at | 2.413 g/cm3 b.p. | ||||
| Triple point | 115.775 K, 73.53 kPa | ||||
| Critical point | 209.48 K, 5.525 MPa | ||||
| Heat of fusion | 1.64 kJ/mol | ||||
| Heat of | 9.08 kJ/mol | ||||
| Molar heat capacity | 20.95 J/(mol·K) | ||||
| pressure | |||||
| Atomic properties | |||||
| Oxidation states | 2, 1, 0 (rarely more than 0; unknown oxide) | ||||
| Electronegativity | Pauling scale: 3.0 | ||||
| energies |
1st: 1350.8 kJ/mol 2nd: 2350.4 kJ/mol 3rd: 3565 kJ/mol | ||||
| Covalent radius | 116±4 pm | ||||
| Van der Waals radius | 202 pm | ||||
| Miscellanea | |||||
| Crystal structure | face-centered cubic (fcc) | ||||
| Speed of sound |
gas (23 °C): 220 m/s liquid: 1120 m/s | ||||
| Thermal conductivity | 9.43×10−3 W/(m·K) | ||||
| Magnetic ordering | Diamagnetic | ||||
| CAS Registry Number | 7439-90-9 | ||||
| Discovery and first isolation | William Ramsay and Morris Travers (1898) | ||||
Krypton is a chemical element with symbol Kr and atomic number 36. Along with xenon and radon, it is the only noble gas to form true chemical compounds.
Contents
Properties
Chemical
Krypton is nonreactive to all chemicals but fluorine.
The reaction of krypton with fluorine gives krypton difluoride (KrF2). KrF2 is made by irradiating krypton with ultraviolet rays in a fluorine-argon gas mixture at -265 °C:
- Kr + F2 → KrF2
Other compounds, such as krypton hydride (Kr(H2)4) are also known. All of these compounds are stable only at very low temperatures.
However, as krypton compounds can only be made with the super dangerous fluorine at very low temperatures and the relative high price of krypton, they have no useful application to the amateur chemist.
Physical
Krypton is a dense, colorless, odorless, non-flammable gas. At standard conditions, krypton has a density of 3.749 g/L being 3 times denser than air, while cryogenic krypton has a density of 2.413 g/cm3. Krypton has the second widest liquid phase range among the noble gasses (after radon), with a boiling point of −157.37 °C and a melting point of −153.415 °C.
Availability
Krypton is sold by various compressed gas companies, though it's quite expensive.
Certain gas discharge lamps contain krypton.
Isolation
Krypton can be isolated from the fractional distillation of air, but this method requires processing extremely large amounts of air and is too expensive for the amateur chemist.
Projects
- Gas discharge lamp
- Element collection
- Inert atmosphere (expensive)
Handling
Safety
Being a noble gas, krypton is non-toxic, though inhaling large amounts of krypton can lead to asphyxiation, as it displaces the air from lungs.
Storage
Krypton cylinders should be stored in dark places, away from any heat source and not in the basement.
Disposal
Krypton can be safely released in the air.
References
Relevant Sciencemadness threads
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