Properties and Overview of Krypton

Overview:

Krypton (Kr) denoted by the chemical symbol Kr and atomic number 36, is a noble gas that is colorless, odorless, and tasteless in its natural state. The chemists Sir William Ramsay and Morris Travers discovered it in 1898 as a residue left after evaporating nearly all components of liquid air. The name "krypton" is derived from the Greek word "kryptos," meaning hidden, reflecting its elusive nature. Physically, krypton is a gas under standard conditions but can be condensed into a colorless liquid at low temperatures. Its boiling point is -153.4°C, and its melting point is -157.4°C. Krypton is heavier than air, with a 3.75 grams per liter density at standard temperature and pressure. Despite being a noble gas, krypton can form solids, and in its solid form, it has a face-centered cubic crystal structure.
Chemically, krypton, as are all noble gases, is highly inert due to its full valence electron shell. This chemical inertness makes krypton extraordinarily stable and resistant to forming compounds. However, under certain extreme conditions, krypton can form a few compounds, most notably with fluorine, such as krypton difluoride (KrF₂). Krypton difluoride is one of the few known krypton compounds which can act as a potent oxidizing agent. Krypton can also be trapped in specific solid matrices, forming clathrates, where the krypton atoms are physically enclosed within the structure of another material, like water ice.
Regarding safety, krypton is generally non-toxic and inert, posing little chemical hazard to humans. However, as with any gas in confined spaces, krypton can displace oxygen and create a risk of asphyxiation. Care must be taken to ensure proper ventilation when working with large quantities of krypton in enclosed environments. Krypton gas is not known to have any significant environmental impact or biological role, and it is not considered a health hazard in typical uses.

Production:

Krypton is produced commercially by the fractional distillation of liquefied air. Air is first cooled to very low temperatures to liquefy its components. Then, krypton, which makes up only about 1 part per million by volume of the atmosphere, is separated during the distillation process. Given its scarcity and specific applications, the production of krypton is relatively small compared to other gases like nitrogen and oxygen.

Applications:

One of the primary applications of krypton is in lighting. Krypton is used in certain types of incandescent light bulbs to reduce filament evaporation, which extends the bulb's lifespan. Krypton-filled bulbs are more efficient than standard argon-filled bulbs and provide brighter, whiter light. Krypton is also used in high-performance flashlights and flashlamps for high-speed photography because it produces a bright, white light when electrified.
In addition to lighting, krypton is used in electronics and energy. It is employed in some gas discharge tubes, such as those used in neon signs, where it emits a whitish glow. It is also used in the production of certain types of lasers, particularly krypton fluoride lasers, which are powerful ultraviolet lasers used in nuclear fusion research and photolithography for microelectronics manufacturing.
Krypton has some specialized uses in science and medicine. One of its isotopes, krypton-85, is used in leak detection for sealed containers, such as in the nuclear industry, where it can help detect small leaks by emitting a traceable radioactive signal. Krypton-85 is also used in some gas-discharge lamps and the calibration of radiation monitoring equipment.

Summary:

Krypton is a rare and relatively expensive noble gas with specific lighting, electronics, and scientific research applications. Its chemical inertness and physical properties make it useful when a stable, non-reactive gas is required, particularly in high-performance and specialized equipment. While krypton is not hazardous under normal conditions, appropriate safety measures are necessary when handling large quantities to prevent asphyxiation risks.

See a comprehensive list of atomic, electrical, mechanical, physical and thermal properties for krypton below: