Krypton (Kr)

Element 36 · noble gas · group 18, period 4

Electron shells, 2 + 8 + 18 + 8. The outer shell is highlighted - it is the only one that takes part in bonding.

Krypton is element 36, a noble gas in group 18 and period 4. Its electron configuration is [Ar] 3d10 4s2 4p6. That leaves 8 valence electrons in the outer shell, with the shells filling 2, 8, 18, 8. Its outer shell is already full, so it does not normally form ions at all.

36 protons
8 valence e−
p-block

Properties

Atomic number	36
Symbol	Kr
Standard atomic weight	83.798 u
Group	18
Period	4
Block	p-block
Category	noble gas
Electron configuration	1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶
Noble-gas notation	[Ar] 3d¹⁰ 4s² 4p⁶
Electrons per shell	2, 8, 18, 8
Valence electrons	8
Common ionic charge	none
Electronegativity (Pauling)	3
Protons / electrons	36 / 36

Electron configuration of krypton

Orbitals fill from the lowest energy upward. Writing that out for krypton gives 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶, which is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 in plain text.

Everything up to Ar is the same as in that noble gas, so it is usually abbreviated to [Ar] 3d¹⁰ 4s² 4p⁶. The part outside the bracket is what does the chemistry.

Subshell	Electrons	Capacity
1s	2	2
2s	2	2
2p	6	6
3s	2	2
3p	6	6
3d	10	10
4s	2	2
4p	6	6

Krypton ion charge

Krypton does not normally form ions. Its outer shell is already full, so there is nothing to gain by losing or gaining an electron.

Common questions

How many valence electrons does krypton have?

Krypton has 8 valence electrons. For a main-group element the count is the group number minus 10, and krypton is in group 18.

What is the electron configuration of krypton?

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6, or [Ar] 3d10 4s2 4p6 written from the previous noble gas. Orbitals fill lowest energy first.

How many protons, electrons and neutrons does krypton have?

A neutral krypton atom has 36 protons and 36 electrons. Its standard atomic weight is 83.798, so the most common isotope has about 48 neutrons.

See the ionic charge of every element →

How this page was produced. The configuration was built by filling orbitals in energy order from atomic number 36 alone, not looked up. The shell counts, the valence count and the charge all follow from it. Nothing on this page is written per element.