Krypton (Kr)
Krypton (Kr) is element 36, a noble gas. Atomic mass 83.798, configuration [Ar] 3d¹⁰ 4s² 4p⁶. Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 36 |
|---|---|
| Symbol | Kr |
| Standard atomic weight | 83.798(2) |
| Category | Noble Gas |
| Group | 18 |
| Period | 4 |
| State at room temperature | Gas |
| Electron configuration | [Ar] 3d¹⁰ 4s² 4p⁶ |
| Valence electrons | 8 |
| Common oxidation states | +2 |
| Common ions | No common ions |
| First ionization energy | 1351 kJ/mol |
| Atomic radius | 88 pm |
| Density | 3.425 g/L |
| Melting point | -157.35°C |
| Boiling point | -153.22°C |
| Specific heat | 0.248 J/(g·°C) |
Natural isotopes
- Kr-78: Stable
- Kr-80: Stable
- Kr-82: Stable
- Kr-83: Stable
- Kr-84: Stable
- Kr-86: Stable
Common uses
- High-speed photography flashes
- Fluorescent bulbs
- Double-pane windows
Where it matters
- Measurement standards (Meter was defined by Kr-86 light 1960-1983)
Hazards
- Asphyxiant
- Radioactive ⁸⁵Kr is a fission product
History
| Discovered | 1898 |
|---|---|
| Discovered by | William Ramsay & Morris Travers |
| Name | From Greek kryptos (hidden) |