Chemical element · Atomic number 36
Krypton
Krypton in the periodic table: atomic number 36, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Noble gas
gaseous
83.80 u
Documented element sampleA krypton filled gas discharge tube shaped like the element symbol Kr glows under high voltage.
Image credit: User:Pslawinski
Auto-oriented, limited to 1600 × 1200 pixels and re-encoded as WebP; the subject was not altered.
Atomic classification
Shell occupancy
Krypton in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 8 electrons
- Electron configuration
- [Ar]4s2 3d10 4p6
- Electrons per shell
- 2 · 8 · 18 · 8
- Group
- 18
- Period
- 4
- Block
- P
- Element category
- Noble gas
Physical and chemical properties
- Atomic mass
- 83.80 u
- Standard state
- gaseous
- Density
- 0.003733 g/cm³
- Melting point
- 115.79 K
- Boiling point
- 119.93 K
- Electronegativity
- 3 (Pauling)
- First ionisation energy
- 14 eV
- Oxidation states
- 0
- Discovery
- 1898
Safety and periodic classification
Safety
Safe handling cannot be inferred from Krypton's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Krypton is in period 4, group 18 and the P block. Its direct neighbours by atomic number are Bromine and Rubidium. The recorded Pauling electronegativity is 3. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.
Where Krypton sits among the 118 elements
The table compares the reported values for Krypton with every other element that carries the same value in the snapshot. A rank is not a judgement, it is orientation: it says how unusual this value is across the periodic table.
| Value | Krypton | Position in the data set |
|---|---|---|
| Melting point | 115.79 K | Rank 96 of 103 elements with a reported value. Highest: Carbon. |
| Boiling point | 119.93 K | Rank 86 of 93 elements with a reported value. Highest: Rhenium. |
| Density | 0.004 g/cm³ | Rank 88 of 96 elements with a reported value. Highest: Osmium. |
| Electronegativity (Pauling) | 3 | Rank 5 of 95 elements with a reported value. Highest: Fluorine. |
| Ionisation energy | 14 eV | Rank 6 of 102 elements with a reported value. Highest: Helium. |
All values and ranks come from the PubChem Periodic Table snapshot, retrieved on 2026-07-15. Elements without a reported value are excluded, so the population differs per row.
The neighbours of Krypton in the periodic table
- Place in the table
- Group 18, period 4, P block. Classified as noble gas, gaseous at standard conditions.
- Direct neighbours
- Atomic number 36. Preceded by Bromine, followed by Rubidium.
- Same group
- Same number of outer electrons, and therefore similar reactivity to Helium, Neon, Argon, Xenon, Radon, Oganesson.
- Discovery
- Recorded in the snapshot as: 1898. Who, where and under what circumstances is not part of that record, so this page carries the sourced year and no discovery narrative.
- Oxidation states
- 0. They follow from the electron configuration [Ar]4s2 3d10 4p6 and indicate which compounds to expect.
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