Helium, neon and argon hardly react with anything. Their atoms already have full outer shells, so they have no reason to gain, lose or share electrons. That same unreactivity is exactly what makes them useful.
The noble gases in Group VIII are unreactive, monatomic gases. Their atoms have full outer shells (helium 2, neon 2,8, argon 2,8,8), so they do not need to gain, lose or share electrons to become stable. Because they are unreactive they are used where a non-reactive gas is needed: argon in lamps and as an inert atmosphere, helium in balloons and airships, neon in advertising signs.
Other elements react in order to reach a full outer shell. The noble gases already have one.
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Why are the noble gases unreactive?
Noble gases are described as monatomic. This means:
Which noble gas is used in filament lamps?
How many electrons are in the outer shell of a neon atom?
Each use depends on the gas being unreactive, together with one other property.
| Gas | Use | Reason |
|---|---|---|
| helium | balloons and airships | unreactive (not flammable) and much less dense than air |
| argon | filament lamps; shielding gas in welding | unreactive, so the hot metal does not react with it |
| neon | advertising signs | glows brightly when electricity passes through it |
Helium replaced hydrogen in airships because it is unreactive (it does not burn), not just because it is light: hydrogen is even less dense but is flammable. And helium has 2 outer electrons, not 8, yet its outer shell is still full.
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Why is helium, rather than hydrogen, used to fill airships?
Which ion has the same electronic configuration as argon?
How do the boiling points of the noble gases change down the group?
Argon is used as a shielding gas when welding metals. Why?
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