Krypton vs Xenon
Krypton and Xenon sit in the same column of the periodic table — same family, one period apart — so almost every difference between them comes from one thing: the extra electron shell Xenon wears.
Side by side
| Property | Krypton | Xenon |
|---|---|---|
| Symbol | Kr | Xe |
| Atomic number (Z) | 36 | 54 |
| Atomic mass | 83.798 u | 131.29 u |
| Category | Noble gas | Noble gas |
| Group | 18 | 18 |
| Period | 4 | 5 |
| Phase at room temp | gas | gas |
| Electron configuration | [Ar] 3d^10 4s^2 4p^6 | [Kr] 4d^10 5s^2 5p^6 |
| Valence electrons | 8 | 8 |
| Atomic radius | 88 pm | 108 pm |
| Electronegativity | 3 | 2.6 |
| First ionisation energy | 1351 kJ/mol | 1170 kJ/mol |
The verdicts
- Bigger atom: Xenon — the lower an element sits in its group, the more shells it wears.
- Greedy electron-taker: Krypton — higher electronegativity means it pulls shared electrons harder.
- Heavier: Xenon — compare the atomic masses in the table above.
Want the visual version with bars for radius, electronegativity and ionisation energy? Open the interactive compare tool with this pair already loaded.