Element category
Noble gases
The noble gases are the group 18 elements from helium to radon. Their outer electron shells are completely full, which leaves almost no drive to gain, lose or share electrons, so they exist as single atoms and rank as the least reactive elements. Only the heavier members, xenon above all, form a limited set of compounds.
At a glance
- Elements
- 6
- Atomic numbers
- 2 to 86
- Blocks
- s-block, p-block
- Periods
- 1, 2, 3, 4, 5, 6
- Phase at STP
- gas (6)
Shared properties
- Full valence electron shells, so chemical reactivity is extremely low
- Colorless, odorless monatomic gases at standard conditions
- Very low boiling points; helium boils closer to absolute zero than any other element
- Used where inertness matters, from lighting and lasers to protective atmospheres