Periodic table group
Group 18
Group 18 is a vertical column of the periodic table containing Helium, Neon, Argon, Krypton, Xenon, Radon, Oganesson. Elements in the same group have the same number of valence electrons, which is why they show related chemical behavior. The noble gases. Their full valence shells make them the least reactive elements, monatomic gases used wherever an inert atmosphere is needed.
At a glance
- Elements
- 7
- Atomic numbers
- 2 to 118
- Blocks
- s-block, p-block
- Periods
- 1, 2, 3, 4, 5, 6, 7
- Phase at STP
- gas (6)
Shared properties
- Same valence electron count, so members react in related ways
- Atomic radius increases down the group as electron shells are added
- First ionization energy generally decreases down the group
The 7 elements
Frequently asked questions
What elements are in group 18?
Group 18 contains 7 elements: Helium, Neon, Argon, Krypton, Xenon, Radon, Oganesson.
What properties do group 18 elements share?
Elements in group 18 have the same number of valence electrons, so they react in related ways. Atomic radius increases down the group as electron shells are added, and first ionization energy generally decreases down the group. The noble gases. Their full valence shells make them the least reactive elements, monatomic gases used wherever an inert atmosphere is needed.
Why are they called the noble gases?
Group 18's elements are the noble gases. Their full valence shells make them the least reactive elements - monatomic gases used wherever an inert atmosphere is needed.