Superman's home planet is named Krypton — and that's no accident. The real krypton is so elusive it was named from the Greek word 'kryptos', meaning 'hidden'. Even more remarkably, this gas once defined the meter itself. For 23 years, the orange glow of krypton-86 served as the world's official standard of length.
Krypton is a noble gas, the fourth member of Group 18. It's colorless, odorless, and almost entirely unreactive. Yet its unique physical properties make it indispensable. It traps heat in windows, produces brilliant white light in lamps, and powers precision lasers.
Krypton makes up just one part per million of Earth's atmosphere. It's extracted through fractional distillation of liquefied air — a slow, expensive process. Producing a single liter requires processing over a thousand cubic meters of air. That's why krypton costs roughly 30 dollars per liter.
Despite its chemical inertness, krypton can form compounds. In 1962, scientists synthesized krypton difluoride (KrF₂). This proved that even 'lazy' noble gases can react under extreme conditions.
Krypton is non-toxic and chemically inert — it does not irritate skin, eyes, or airways. However, at high concentrations it displaces oxygen and can cause asphyxiation without any warning symptoms. In cylinders, it's stored at pressures up to 150 atmospheres. Work with krypton should be done in well-ventilated areas equipped with oxygen monitors.
The name 'krypton' means 'hidden' — from the Greek kryptos. It was the last gas discovered in air because it hides at a concentration of just 1 ppm.
From 1960 to 1983, the meter was defined as 1,650,763.73 wavelengths of orange light from krypton-86. A more precise standard came only with laser technology.
Krypton lamps produce bright white light with a bluish tint. That's why they're used in airport runway lights — pilots can spot them from kilometers away.
Although krypton is an inert gas, scientists created krypton difluoride (KrF₂) in 1962. This compound exists only below −78 °C.
Krypton conducts heat three times worse than air. So a thin layer of krypton between window panes replaces a much thicker layer of ordinary air.
One liter of krypton costs about $30. To obtain it, you need to process over 1,000 cubic meters of air — because its concentration is only 0.0001%.
| Isotope | Mass (u) | Abundance | Half-life | Decay |
|---|---|---|---|---|
78Kr | 77.920365 | 0.35% | stable | — |
80Kr | 79.916379 | 2.28% | stable | — |
82Kr | 81.913484 | 11.58% | stable | — |
83Kr | 82.914136 | 11.49% | stable | — |
84Kr | 83.911507 | 57.00% | stable | — |
86Kr | 85.910611 | 17.30% | stable | — |
Fractional distillation of liquid air