Krypton (Kr)
Noble gas · p-block · period 4 · group 18
Colourless, odourless gas; glows whitish in a discharge tube.
Krypton (symbol Kr) is chemical element number 36, a noble gas in group 18, period 4 of the periodic table. Its standard atomic weight is 83.798 and its electron configuration is [Ar] 3d10 4s2 4p6. At room temperature it is a gas. Its name means 'the hidden one' in Greek.
Properties
| Atomic number | 36 |
|---|---|
| Atomic mass | 83.798 |
| Category | Noble gas |
| Block | p-block |
| Group · Period | 18 · 4 |
| Electron configuration | [Ar] 3d10 4s2 4p6 |
| Electrons per shell | 2, 8, 18, 8 |
| State at 25 °C | gas |
| Melting point | 115.79 K |
| Boiling point | 119.93 K |
| Density | 3.749 g/L |
| Electronegativity (Pauling) | 3 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1898 · Ramsay & Travers |
Key facts about Krypton
- Its name means 'the hidden one' in Greek.
- For years the metre was officially defined by the wavelength of light from a krypton lamp.
- Almost inert, though it can be forced to bond with fluorine.
- Fills energy-saving windows and some high-performance light bulbs.
What Krypton is used for
High-performance window insulation, photographic flashes, some lasers, energy-efficient lighting.
Where it sits in the periodic table
Krypton is in group 18, period 4, of the p-block. Its electron configuration [Ar] 3d10 4s2 4p6 means its outermost shell holds 8 electrons, which is what places it here and explains much of its chemistry. See Krypton on the interactive table →
Krypton — frequently asked questions
What is Krypton used for?
High-performance window insulation, photographic flashes, some lasers, energy-efficient lighting.
Is Krypton radioactive?
No. Krypton has at least one stable isotope and is not radioactive.
What is the electron configuration of Krypton?
Krypton has the electron configuration [Ar] 3d10 4s2 4p6, which is 2, 8, 18, 8 electrons per shell.
What group and period is Krypton in?
Krypton is in group 18, period 4, in the p-block. Its outer shell holds 8 electrons.
Who discovered Krypton?
Krypton was discovered in 1898 by Ramsay & Travers.