Element Krypton
Krypton (from Ancient Greek: κρυπτός, romanized: kryptos “the hidden one”) is a chemical element with the symbol Kr and atomic number 36.
It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. With rare exceptions, krypton is chemically inert.
Krypton, like the other noble gases, is used in lighting and photography. Krypton light has many spectral lines, and krypton plasma is useful in bright, high-powered gas lasers (krypton ion and excimer lasers), each of which resonates and amplifies a single spectral line.
Names and Identifiers
| Chemical Formula: | Kr |
| CAS: | 7439-90-9 |
| Molecular Weight: | 83.79800 g/mol |
| EC Number : | n/a |
| MDL Number: | MFCD00151310 |
| Color: | colorless |
| Other Names: | Cripto |
| PubChem CID: | 5416 |
| IUPAC Name: | Krypton |
| Inchl: | InChI=1S/Kr |
| InChI Key: | DNNSSWSSYDEUBZ-UHFFFAOYSA-N |
| Canonical SMILES: | [Kr] |
| ICSC Number: | 0604 |
Physical & Chemical Properties
| Phase: | Gas |
| Density: | 3.749 g/L |
| Boiling Point: | 119.93 K (−153.415 °C, −244.147 °F) |
| Melting Point: | 115.78 K (−157.37 °C, −251.27 °F) |
| Molecular Formula: | Kr |
| Flash Point: | n/a |
| Exact Mass: | 83.91150 |
| Symbol: |  |
| Signal Word: | Warning |
| Hazard Statements: | H280 |
| Precautionary Statements: | n/a |
| Hazard Codes: | n/a |
| Risk Phrases: | R9 |
| Safety Phrases: | 9-38 |
| RIDADR: | UN 1950 2 |
| WGK Germany: | 3 |
| RTECS: | n/a |
| Packaging Group: | n/a |
| Hazard Class: | 2.2 |
Krypton isotopes are used in various medical and scientific applications. Kr-82 is used for the production of Rb-81/Kr-81m generators.
Many of the stable isotopes of Krypton are used in the study of the pulmonary system. Kr-78 can be used for the production of Br-75 although production of Br-75 via Se-76 is more common. Kr-86 has been used to define the standard measure of length: 1 meter is exactly 1,650,763.73 wavelengths of this isotope.
Naturally occurring isotopes
| Isotope | Mass/Da | Natural abundance (atom %) | Nuclear spin (I) | Magnetic moment (μ/μN) |
|---|---|---|---|---|
| 78Kr | 77.920396 (9) | 0.35 (1) | 0 | |
| 80Kr | 79.916380 (9) | 2.28 (6) | 0 | |
| 82Kr | 81.913482 (6) | 11.58 (14) | 0 | |
| 83Kr | 82.914135 (4) | 11.49 (6) | 9/2 | -0.970669 |
| 84Kr | 83.911507 (4) | 57.00 (4) | 0 | |
| 86Kr | 85.910616 (5) | 17.30 (22) | 0 |
Radiosotope data
| Isotope | Mass/Da | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
|---|---|---|---|---|---|
| 74Kr | 73.9333 | 11.5 m | EC to 74Br | 0 | |
| 75Kr | 74.93104 | 4.3 m | EC to 75Br | ||
| 76Kr | 75.92595 | 14.8 h | EC to 76Br | 0 | |
| 77Kr | 76.92467 | 1.24 h | EC to 77Br | 5/2 | |
| 79Kr | 78.920083 | 1.455 d | EC to 79Br | 1/2 | |
| 81Kr | 80.916593 | 210000 y | EC to 81Br | 7/2 | |
| 85Kr | 84.912530 | 10.73 y | β– to 85Rb | 9/2 | 1.005 |
| 87Kr | 86.913359 | 1.27 h | β– to 87Rb | 5/2 | -1.018 |
| 88Kr | 87.91445 | 2.84 h | β– to 88Rb | 0 | |
| 89Kr | 88.91764 | 3.15 m | β– to 89Rb | 5/2 |