Krypton (Kr)
Krypton is element 36, a noble gas in period 4, group 18 of the periodic table. At room temperature it is a gas.
Electron configuration [Ar] 3d10 4s2 4p6
Electrons per shell 2, 8, 18, 8
Krypton data
| Atomic number | 36 |
|---|---|
| Symbol | Kr |
| Atomic mass | 83.798 u |
| Category | Noble gas |
| Group | 18 |
| Period | 4 |
| Block | p |
| State at 25 °C | gas |
| Melting point | 116 K (-157.1 °C) |
| Boiling point | 120 K (-153.1 °C) |
| Density | 0.00375 g/cm³ (3.75 g/L) |
| Electronegativity (Pauling) | — |
| Atomic radius | 110 pm |
| 1st ionization energy | 1351 kJ/mol |
| Electron affinity | 0 kJ/mol |
| Oxidation states | +2 |
| Common ion charge | 0 |
| Discovered | 1898 |
Orbital diagram
Each box is one orbital holding up to two electrons of opposite spin. Following Hund’s rule, electrons spread out singly across a subshell before pairing.
Work through krypton’s configuration and its ions →
Where krypton sits
Krypton belongs to the noble gases. To use its mass in a calculation, try the molar mass calculator.
Krypton FAQ
What is the electron configuration of krypton?
Krypton (Z = 36) has the configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6. In noble-gas shorthand that is [Ar] 3d10 4s2 4p6.
How many valence electrons does krypton have?
8 (full outer shell).
What is the atomic mass of krypton?
The standard atomic weight of krypton is 83.798 u, so one mole weighs 83.798 g.
Is krypton a metal?
No. Krypton is a noble gas.
What is the charge of a krypton ion?
Krypton most commonly forms no ions.