Krypton
Krypton, like the other noble gases, can be used in lighting and photography. Krypton light has a large number of spectral lines, and krypton's high light output in plasmas allows it to play an important role in many high-powered gas lasers (krypton ion and excimer lasers), which pick out one of the many spectral lines to amplify. There is also a specific krypton fluoride laser. The high power and relative ease of operation of krypton discharge tubes caused (from 1960 to 1983) the official length of a meter to be defined in terms of the 605 nm (red-orange) spectral line of krypton-86.
Natural occurrence
he Earth has retained all of the noble gases that were present at its formation except for helium. Krypton's concentration in the atmosphere is about 1 ppm. It can be extracted from liquid air by fractional distillation. The amount of krypton in space is uncertain, as the amount is derived from the meteoric activity and that from solar winds. The first measurements suggest an overabundance of krypton in space.
| Symbol | Kr | |
| Atomic Number | 36 | |
| Atomic Weight | 83.8 | |
| Oxidation States | 0 | |
| Electronegativity, Pauling | ||
| State at RT | Gas, Nonmetal | |
| Melting Point, K | 116.6 | |
| Boiling Point, K | 120.85 |
Interesting Facts about Krypton
- Between 1960 and 1983, the scientific unit of length, the meter, was defined as 1 650 763.73 wavelengths of krypton-86′s orange-red spectral line. (The meter is now defined as the distance travelled by light in a vacuum during a time interval of (1/299 792 458 of a second.)
- From its discovery in 1898 until the 1960s most scientists believed it was impossible to make compounds of krypton, or any other noble gas – although see William Ramsay, above. Krypton difluoride was made in 1963. It is a white, crystalline solid, stable at temperatures below -30 oC.
- Krypton is not very abundant in our planet’s atmosphere: For every krypton atom, there are about 8200 argon atoms, 184 000 oxygen molecules and 685 000 nitrogen molecules.
- Krypton-85 in the atmosphere can be used to detect the presence of otherwise secret nuclear weapons research and production facilities.
- Krypton-fluorine lasers produce pulses with 500 times the power of the entire U.S. electrical grid. Not surprisingly, these pulses are of short duration: four billionths of a second.
Appearance and Characteristics
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 the very reactive gas fluorine. A few compounds of krypton have been prepared, including krypton (II) fluoride and krypton clathrates.
- Solid krypton is white and crystalline.
Uses of Krypton
- Krypton is used in lighting products:
- An important use is in high-powered, flashing airport runway lights.
- 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.
- Krypton is employed alongside other gases to make luminous ‘neon light‘ style signs that glow with a greenish-yellow light.
- Krypton is used as a filling gas for energy-saving fluorescent lights and as an inert filling gas in incandescent bulbs.
- The relative abundance of krypton versus hydrogen can be used by astronomers to measure how much nucleosynthesis (element formation) has taken place in any region of interstellar space.
- Between 1960 and 1983, 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.)
