Element 36
Krypton (Kr)
Krypton (Kr) is element 36 of the periodic table, a noble gas in period 4, group 18 (p-block) with an atomic mass of 83.798 and is a gas at standard conditions.
At a glance
- Atomic number
- 36
- Symbol
- Kr
- Atomic mass
- 83.798 u
- Category
- Noble gases
- Period
- 4
- Group
- 18
- Block
- p-block
- Phase at STP
- gas
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6
- Shorthand configuration
- [Ar] 3d10 4s2 4p6
- Electrons per shell
- 2, 8, 18, 8
- Oxidation states
- 0, +2
Physical properties
- Melting point
- 115.79 K (-157.36 °C)
- Boiling point
- 119.93 K (-153.22 °C)
- Density
- 0.003733 g/cm³
- Phase
- gas
Atomic properties
- Electronegativity (Pauling)
- 3
- Atomic radius
- 88 pm
- Covalent radius
- 116 pm
- Van der Waals radius
- 202 pm
- First ionization energy
- 1351 kJ/mol
- Electron affinity
- 0 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Kr-84 | 83.9115 | 57% | Stable |
Common uses
- Lighting
- Lasers
- Photography
- Insulation
Discovery
- Year
- 1898
- Discovered by
- William Ramsay, Morris Travers
- Country
- England
Frequently asked questions
- Is krypton a metal?
- No. Krypton is a nonmetal, classified as a noble gas on the periodic table.
- How many protons does krypton have?
- Krypton has 36 protons. Its atomic number is 36, which is also the number of electrons in a neutral atom of krypton.
- What group and period is krypton in?
- Krypton is in group 18 and period 4 of the periodic table, in the p-block.
- What is the atomic mass of krypton?
- The atomic mass of krypton is 83.798 u (unified atomic mass units).
Keep exploring
Krypton's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.