Nuclides
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Chemical element · Atomic number 36
Krypton (Kr)
Noble gases · Period 4 · Gas
Element identity
- Atomic number (Z)
- 36
- Symbol
- Kr
- Atomic weight / isotope mass number
- 83.798(2)
- Category
- Noble gases
- Physical state (reference)
- Gas
- Period
- 4
- Group (reference)
- 18
- Block
- p
Physical properties
- Appearance
- Colorless gas, exhibiting a whitish glow in a high electric field
- Density
- 3.749×10⁻³ g·cm⁻³
- Melting point
- 115.78 K / −157.37 °C / −251.27 °F
- Boiling point
- 119.93 K / −153.415 °C / −244.147 °F
- Sublimation point
- Not available
Atomic and material properties
- Electron configuration
- [Ar] 3d¹⁰ 4s² 4p⁶
- Electrons per shell
- K2 L8 M18 N8
- Oxidation states
- 2, 1, 0
- Electronegativity (Pauling)
- 3
- Atomic radius
- 88 pm
- Covalent radius
- 116±4 pm
- Molar ionization energies
- 1st: 1350.8 kJ·mol⁻¹ 2nd: 2350.4 kJ·mol⁻¹ 3rd: 3565 kJ·mol⁻¹ 4th: 5070 kJ·mol⁻¹ 5th: 6240 kJ·mol⁻¹ 6th: 7570 kJ·mol⁻¹ 7th: 10,710 kJ·mol⁻¹ 8th: 12,138 kJ·mol⁻¹ 9th: 22,274 kJ·mol⁻¹ 10th: 25,880 kJ·mol⁻¹ 11th: 29,700 kJ·mol⁻¹ 12th: 33,800 kJ·mol⁻¹ 13th: 37,700 kJ·mol⁻¹ 14th: 43,100 kJ·mol⁻¹ 15th: 47,500 kJ·mol⁻¹ 16th: 52,200 kJ·mol⁻¹ 17th: 57,100 kJ·mol⁻¹ 18th: 61,800 kJ·mol⁻¹ 19th: 75,800 kJ·mol⁻¹ 20th: 80,400 kJ·mol⁻¹ 21st: 85,300 kJ·mol⁻¹ 22nd: 90,400 kJ·mol⁻¹ 23rd: 96,300 kJ·mol⁻¹ 24th: 101,400 kJ·mol⁻¹ 25th: 111,100 kJ·mol⁻¹ 26th: 116,290 kJ·mol⁻¹ 27th: 282,500 kJ·mol⁻¹ 28th: 296,200 kJ·mol⁻¹ 29th: 311,400 kJ·mol⁻¹ 30th: 326,200 kJ·mol⁻¹
- Thermal conductivity
- 9.43×10⁻³ W·m⁻¹·K⁻¹
- Molar heat capacity
- 20.95 J·mol⁻¹·K⁻¹
- Crystal structure
- Face-centered cubic
- CAS number
- 7439-90-9
Property source: Wikipedia — Krypton, adapted from the Nuclides App snapshot. Quoted conditions and qualifiers are retained.
Sources and interpretation
Snapshot exported 24 October 2026 from the element assets used by Nuclides. Properties are a reference compilation, not a new evaluation. Missing values are shown as “Not available”. Density and phase depend on temperature, pressure and allotrope; retained conditions are part of the quoted property.
Atomic weight is dimensionless. Parentheses give uncertainty in the last quoted digits. A single integer in square brackets is an isotope mass number, not a standard atomic weight. The snapshot can differ from current evaluations; consult CIAAW standard atomic weights and the IUPAC periodic table for current values and conventions.
Element properties in the App snapshot are adapted from Wikipedia. Each element page links to its source article; text adaptations are available under CC BY-SA 4.0. No third-party images are included.
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