Krypton (Kr): Electron Configuration, Properties and Uses
Krypton (Kr): Electron Configuration, Properties and Uses
Electron configuration [Ar] 4s2 3d10 4p6 · group 18 · period 4 · Ar 83.798
Krypton data
- Atomic number
- 36
- Relative atomic mass
- 83.798
- Group
- 18
- Period
- 4
- Block
- p
- Category
- Noble gas
- Electron configuration
- [Ar] 4s2 3d10 4p6
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
- Electrons per shell
- 2, 8, 18, 8 (K L M N)
- Valence electrons
- 8
- Electronegativity (Pauling)
- 3
- First ionisation energy
- 14 eV
- Atomic radius (van der Waals)
- 202 pm
- State at room temperature
- Gas
- Melting point
- −157 °C
- Boiling point
- −153 °C
- Density
- 3.733 g/L (0 °C, 1 atm)
- Common oxidation states
- 0
- Discovered
- 1898
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 8
Orbital diagram (outer electrons)
About krypton
Krypton is a chemical element with the symbol Kr and atomic number 36. It is a noble gas in group 18, period 4, p-block. Krypton was first discovered in 1898. At room temperature krypton is a gas that is heavier than air (3.733 g/L) and liquefies at −153 °C.
Krypton electron configuration
The electron configuration of krypton is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6, or in short [Ar] 4s2 3d10 4p6. Its electrons occupy 4 shells: K = 2, L = 8, M = 18, N = 8. Krypton has 8 valence electrons in the N shell (4s2 4p6), which is why it sits in group 18.
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p6(36)
Uses of krypton
The main uses of krypton include photographic flash lamps, energy-saving lamps and filling double-glazed windows.
Safety
Krypton is non-toxic and almost unreactive, but large amounts in a closed room can displace oxygen. Always read the safety data sheet (SDS) before working with a chemical.
Other elements in group 18
Frequently asked questions
What is the electron configuration of krypton?
The electron configuration of krypton (Kr, atomic number 36) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6, or [Ar] 4s2 3d10 4p6 in short. By shell: 2, 8, 18, 8.
How many valence electrons does krypton have?
Krypton has 8 valence electrons.
Which group and period is krypton in?
Krypton is in group 18, period 4, p-block.
What is the atomic mass of krypton?
The relative atomic mass of krypton is 83.798. Use it to calculate molar mass with the molar mass calculator.
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