Krypton (Kr)
From 1960 to 1983, the meter was officially defined by the wavelength of orange-red light given off by krypton-86 atoms.
Krypton properties
- Atomic mass
- 83.798 u
- Category
- Noble gas
- Group
- 18
- Period
- 4
- Block
- p-block
- Melting point
- 115.78 K (-157.4 °C)
- Boiling point
- 119.93 K (-153.2 °C)
- Density
- 3.733 g/L
- Atomic radius
- 202 pm
- Ionization energy
- 14 eV
- Electron affinity
- —
- Radioactive
- No, has stable isotopes
- Discovered
- 1898
Krypton electron configuration
- Electron configuration
- [Ar] 3d10 4s2 4p6
- Full electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6
- Electron shells
- 2 · 8 · 18 · 8
The electron configuration of Krypton (Kr) is [Ar] 3d10 4s2 4p6. Its 36 electrons are arranged in shells as 2, 8, 18, 8.
Protons, neutrons and electrons in Krypton
A neutral Krypton atom has 36 protons and 36 electrons. Most Krypton atoms have about 48 neutrons: the atomic mass rounded to 84, minus the atomic number 36.
Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass
How many valence electrons does Krypton have?
8
Krypton has 8 valence electrons in its outermost shell, shell 4. These are the electrons involved in chemical bonding.
Krypton orbital diagram
Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations
Molar mass of Krypton
83.798 g/mol
One mole of Krypton atoms (6.022 × 10²³ atoms) has a mass of 83.798 grams. Use this value to convert between grams and moles.
Krypton facts
- From 1960 to 1983, the meter was officially defined by the wavelength of orange-red light given off by krypton-86 atoms.
- Krypton is not completely unreactive: with fluorine it forms krypton difluoride (KrF2), an extremely powerful oxidizing agent.
- Krypton (Kr) has atomic number 36 and is a gas at room temperature. It was discovered in 1898.
Position in the periodic table
Krypton is element 36, in period 4 and group 18 of the periodic table, in the p-block.
Uses of Krypton
Krypton is used in some energy-efficient windows, where it fills the narrow gap between the panes and slows heat loss. It is also used in certain lighting, including some photographic flash lamps and high-performance bulbs. Krypton fluoride lasers help make computer chips and are used in fusion research, and some satellite thrusters use krypton as a cheaper alternative to xenon.
Who discovered Krypton?
William Ramsay and Morris Travers discovered krypton in 1898 at University College London, by evaporating liquefied air and examining the small residue left behind. They named it after the Greek kryptos, meaning 'hidden'.
Where does the name come from?
Krypton comes from the Greek kryptos, meaning 'hidden'. William Ramsay and Morris Travers named it in 1898 because the gas had lain hidden in the air, in tiny amounts, until they separated it from liquefied air.
Same group
Compare Krypton
FAQ
What is the electron configuration of Krypton?
The electron configuration of Krypton (Kr) is [Ar] 3d10 4s2 4p6. Its 36 electrons are arranged in shells as 2, 8, 18, 8.
How many protons, neutrons and electrons does Krypton have?
A neutral Krypton atom has 36 protons and 36 electrons. Most Krypton atoms have about 48 neutrons: the atomic mass rounded to 84, minus the atomic number 36.
How many valence electrons does Krypton have?
Krypton has 8 valence electrons in its outermost shell, shell 4. These are the electrons involved in chemical bonding.
What is the molar mass of Krypton?
The molar mass of Krypton is 83.798 g/mol. This is the same number as its atomic mass, 83.798 u.
Is Krypton a metal?
No. Krypton is a noble gas, so it is a nonmetal.
Is Krypton radioactive?
Ordinary Krypton is not radioactive: it has at least one stable isotope. Like every element, it also has radioactive isotopes, most of them made in laboratories.
Where is Krypton on the periodic table?
Krypton is element 36, in period 4 and group 18 of the periodic table, in the p-block.