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What group is radon in on the periodic table?

By Radon411 Editorial TeamUpdated October 1, 2026How we research

Short answer

Radon is in group 18, the noble gases, also called the zero group of gases, and in period 6. It is element 86, symbol Rn, a non-metal that sits directly below xenon in the column, with oganesson, element 118, listed after it.

Next step: a test is the only way to know your home's level. How to test your home

Radon is in group 18, the noble gases, and in period 6. It is essentially inert and takes the last place in the zero group of gases, another name for the same column. Oganesson, element 118, is also listed in the noble gas block today, expected to be a gas.

The group holds helium, neon, argon, krypton, xenon and radon. Radon's electron configuration, [Xe] 6s2 4f14 5d10 6p6, ends in a filled 6s2 6p6 outer shell, and like every noble gas from helium down it is listed with an oxidation state of 0.

Its neighbors in the table are relevant to where radon comes from. Uranium eventually decays to radium, and radium decays to release radon. Radium, element 88, is a member of the alkaline-earth group of metals, while radon is element 86.

What to do next: read the radon element guide for the full property table and the decay chain, and check your area on the radon map before you test.

Radon's place in the periodic table

Radon is in group 18, the noble gases, and in period 6. An element's classification follows its chemical and physical properties and its location in the table, and on both counts radon is a non-metal in the noble gas block.

Radon's address in the periodic table
Property	Radon
Symbol	Rn
Atomic number	86
Group	18 (noble gases)
Period	6
Group block	Noble gas
Classification	Non-metal

The members of group 18

Group 18 runs down the right-hand edge of the table. Each member has a filled outer shell, and each is a gas. Radon is the sixth, directly below xenon, and oganesson follows as the seventh.

Group 18, top to bottom
Element	Atomic number	Electron configuration	State
Helium (He)	2	1s2	Gas
Neon (Ne)	10	[He] 2s2 2p6	Gas
Argon (Ar)	18	[Ne] 3s2 3p6	Gas
Krypton (Kr)	36	[Ar] 4s2 3d10 4p6	Gas
Xenon (Xe)	54	[Kr] 5s2 4d10 5p6	Gas
Radon (Rn)	86	[Xe] 6s2 4f14 5d10 6p6	Gas
Oganesson (Og)	118	Not listed	Expected to be a gas

The zero group: another name for the same column

The noble gases are also called the zero group of gases, and radon occupies the last place in it. Every noble gas from helium to radon is listed with an oxidation state of 0. Radon's listing adds 6 and 2, because it can, rarely, react: radon fluoride is its only confirmed compound.

How the group changes from top to bottom

Down group 18 the atoms get larger, and the energy needed to remove an electron falls. Helium's first ionization energy is 24.587 eV; radon's is 10.745 eV, the lowest of the group. Helium is also the lightest member, at an atomic mass of 4.00260, and radon the heaviest, at 222.01758.

Atomic radius and first ionization energy down group 18
Element	Atomic radius (pm)	First ionization energy (eV)
Helium	140	24.587
Neon	154	21.565
Argon	188	15.760
Krypton	202	14.000
Xenon	216	12.130
Radon	220	10.745

Radon has also been reported to react with fluorine, forming radon fluoride, its only confirmed compound.

Where radon's parents sit

Radon's group says nothing about where it comes from; its decay chain does. Uranium eventually decays to radium, and radium decays to release radon, which then decays into polonium-218. Each of those elements belongs to a different part of the table.

Radon's decay chain neighbors and their classes
Element	Atomic number	Class	Link to radon
Uranium	92	Actinide; a silvery-white metal when refined	Eventually decays to radium
Radium	88	Alkaline-earth metal	Decays into radon-222 through alpha decay
Radon	86	Noble gas	The gas between radium and polonium
Polonium	84	Metalloid	Radon-222 decays into polonium-218

Radium-226, the parent of radon-222, has a half-life of about 1,600 years. See is radon a metal.

What group 18 means in a home

Its group is why radon moves so freely. It typically moves up through the ground to the air above and into a home through cracks and other holes in the foundation. Since radon is a noble gas, it releases from any chemical bonds that attach it and may travel far enough to reach groundwater or the air. Indoors, a home traps radon, where it can build up.

Questions about radon's group

What group is radon in?

Group 18, the noble gases, also called the zero group of gases.

What period is radon in?

Period 6, the same row as lead, bismuth, polonium and astatine.

What family does radon belong to?

The noble gas family, with helium, neon, argon, krypton and xenon, and oganesson listed after it.

Why is radon in group 18?

An element's classification follows its chemical and physical properties and its place in the table. Radon is a noble gas with a filled 6s2 6p6 outer shell, like the members above it.

How many elements are in group 18?

Seven are listed: helium, neon, argon, krypton, xenon, radon and oganesson, which is expected to be a gas.

Is radon in the same group as xenon?

Yes. Xenon, element 54, sits directly above radon in group 18.

What block is radon in?

Its group block is listed as noble gas, and its electron configuration ends in a filled 6p subshell.

Is radon an alkaline earth metal like radium?

No. Radium, element 88, is an alkaline-earth metal. Radon, element 86, is a noble gas and a non-metal.

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