Krypton (Kr): electron configuration, atomic mass and facts
Krypton (Kr) is element 36 of the periodic table, a noble gas in period 4, group 18. Its electron configuration is [Ar] 3d10 4s2 4p6, with electrons arranged in shells 2, 8, 18, 8, and its standard atomic weight is 83.798 u.
▶ Watch Krypton’s electrons orbit in the interactive periodic tableKrypton at a glance
| Symbol | Kr |
|---|---|
| Atomic number | 36 |
| Atomic mass | 83.798 u |
| Category | Noble gas |
| Group | 18 |
| Period | 4 |
| Block | p-block |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 |
| Noble-gas shorthand | [Ar] 3d10 4s2 4p6 |
| Electrons per shell | 2, 8, 18, 8 |
| Outer-shell electrons | 8 |
| Electronegativity (Pauling) | 3 |
| State at 20 °C | gas |
Where is Krypton on the periodic table?
Krypton is in period 4, group 18, in the p-block. The period number matches its 4 electron shells, and the block names the subshell its last electrons fill. In the same group, Argon sits directly above it and Xenon sits directly below it. Elements in one group have the same number of outer-shell electrons (8 here), which is why they react in similar ways.
How to work out the electron configuration of Krypton
Put 36 electrons into subshells in order of rising energy, filling each before starting the next: 1s² (2), 2s² (4), 2p⁶ (10), 3s² (12), 3p⁶ (18), 4s² (20), 3d¹⁰ (30), 4p⁶ (36). In shorthand, [Ar] stands for the 18 electrons of argon, giving [Ar] 3d¹⁰ 4s² 4p⁶.
How electronegative is Krypton?
Krypton has a Pauling electronegativity of 3, ranking 5 of the 100 elements with a known value (fluorine is highest at 3.98). That is high: it pulls shared electrons strongly towards itself in a bond.
Frequently asked questions
What is the electron configuration of Krypton?
The electron configuration of Krypton (Kr) is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6. In noble-gas shorthand it is written [Ar] 3d10 4s2 4p6.
How many electrons does Krypton have in each shell?
Krypton has 36 electrons arranged in shells as 2, 8, 18, 8. It has 8 electrons in its outer shell.
What is the atomic mass of Krypton?
The standard atomic weight of Krypton is 83.798 u, so one mole of Krypton atoms has a mass of about 83.798 g.
Is Krypton a metal?
No. Krypton is a noble gas.
Explore nearby elements
More noble gass: Helium, Neon, Argon, Xenon, Radon, Oganesson. See all elements on the periodic table.