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Krypton

Element 36 · Noble gas

Specimen

Atomic number
36
Atomic mass
83.8
State at room temperature
Gas
Melting point
-157.4 °C
Boiling point
-153.2 °C
Density
0.003733 g/cm³
Discovered
1898

Physical data from PubChem.1

Can I eat it?

In food and water
Not needed, little harm known. Krypton is a gas that does not react with other substances, and it is not toxic. In a closed space, it can push out oxygen and cause suffocation. 2

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The atom

Kr
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) outermost 8
Total36

Configuration [Ar] 3d¹⁰ 4s² 4p⁶

3d ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
4s ↑ ↓
4p ↑ ↓ ↑ ↓ ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 36 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Ar core, with one arrow per electron.

Related elements

Group 18
He Helium Ne Neon Ar Argon Xe Xenon Rn Radon Og Oganesson

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Sources

  1. 1

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Atomic mass, electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  2. 2

    National Center for Biotechnology Information (PubChem), with text from CAMEO Chemicals and ICSC, 2026. Krypton (CID 5416), compound summary , Safety and Hazards, Hazards Summary and Reactivity Profile.

    • Can displace oxygen in a confined space and cause simple asphyxia
    • These substances undergo no chemical reactions under any known circumstances. They are nonflammable, noncombustible and nontoxic. They can asphyxiate.