K

Krypton

IUPAC: Krypton

Kr Elements CAS 7439-90-9
Quick Reference
Formula / NotationKr
CAS Number7439-90-9
Molecular Weight83.8
Melting Point-157.4
Boiling Point-153.4
Density0.00375
Solubility110 mg/L at 0 C
AppearanceColourless, odourless monatomic gas
Also Known AsKr, krypton gas
CategoryElements

What is Krypton?

Krypton is a colourless, odourless noble gas, atomic number 36. Chemically inert under normal conditions. Used in lighting and as a standard of length. Named from the Greek kryptos meaning hidden. One of the rarest stable elements.

Formula & Notation

Kr

IUPAC Name: Krypton

Other Names / Synonyms: Kr, krypton gas

Properties & Characteristics

Atomic number: 36. Atomic mass: 83.798 g/mol. Period 4, Group 18 (noble gas). Boiling point: -153.4 C. Melting point: -157.4 C. Density: 3.75 g/L (STP). Six stable isotopes. Rare in atmosphere: 1.1 ppm. Krypton fluorides can be formed under extreme conditions.

Physical Data

PropertyValue
Melting Point-157.4
Boiling Point-153.4
Density0.00375
Molecular Weight83.8
Solubility110 mg/L at 0 C
AppearanceColourless, odourless monatomic gas

Uses & Applications

High-intensity lighting (krypton flash lamps). Energy-saving light bulbs. Krypton-85 in leak detection. Nuclear industry (Kr-85 fission product as tracer). Laser medium. Historical SI definition of metre (Kr-86 wavelength).

Safety Information

Asphyxiation hazard in enclosed spaces. Cryogenic liquid krypton: cold burns. Krypton-85: radioactive fission product, beta/gamma emitter. Otherwise chemically inert and non-toxic.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Krypton
Formula Kr
CAS Number 7439-90-9
Molecular Weight 83.8
Category Elements
Synonyms Kr, krypton gas

Frequently Asked Questions

Krypton is a colourless, odourless noble gas, atomic number 36. Chemically inert under normal conditions. Used in lighting and as a standard of length. Named from the Greek kryptos meaning hidden. One of the rarest stable elements.

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