Okay, helium balloons room light...but they"re no that light! The cool image below serves to make the allude that helium is one of the lightest elements. Helium belongs come a team of aspects called the noble gases.

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Figure \(\PageIndex1\): Helium is one of the lightest facets in the regular table.

What are Noble Gases?

Noble gases space nonreactive, nonmetallic facets in team 18 that the regular table. As you can see in the routine table in the number below, noble gases incorporate helium \(\left( \ceHe \right)\), neon \(\left( \ceNe \right)\), argon \(\left( \ceAr \right)\), krypton \(\left( \ceKr \right)\), xenon \(\left( \ceXe \right)\), and radon \(\left( \ceRn \right)\). Every noble gases room colorless and odorless. They also have low boiling points, which explains why they are all gases at room temperature. Radon, in ~ the bottom the the group, is radioactive, so that constantly decays to various other elements.

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Figure \(\PageIndex2\): Noble gases room in group 18 the the regular table, in this instance the red pillar on the much right.

mslsec.comical nature of Noble Gases

Noble gases are the least reactive that all recognized elements. Their outer energy levels room full since they each have actually eight valence electrons. The only exception is helium, which has actually just two electrons. However helium additionally has a full outer energy level, since its only power level (energy level 1) can hold a best of two electrons. A full outer power level is the most stable arrangement of electrons. As a result, noble gases cannot become more stable by reacting with various other elements and also gaining or shedding valence electrons. Therefore, noble gases room rarely affiliated in mslsec.comical reaction and practically never form compounds with various other elements.


Noble Gases and also the Octet Rule

Because the noble gases are the the very least reactive of all elements, their eight valence electron are supplied as the traditional for non-reactivity, and to explain how other aspects interact. This is stated as the octet ("group of eight") rule. According to this rule, atoms react to form compounds that enable them to have actually a team of eight valence electrons prefer the noble gases. For example, sodium (with one valence electron) reacts v chlorine (with seven valence electrons) to kind the steady compound sodium chloride (table salt). In this reaction, sodium donates one electron and chlorine accepts it, offering each element an octet the valence electrons.


Some uses of Noble Gases

Have you ever before hadhelium balloons choose those in the elephant image? uneven a balloon filled v air, a balloon filled with helium requirements to it is in weighted under so that it won"t rise away—although you don"t have to use an elephant!

Early incandescent light bulbs, like the one pictured in the number below, didn"t last an extremely long. The filaments quickly shed out. Back air was pumped the end of the bulb, it wasn"t a complete vacuum. Oxygen in the tiny amount of air remaining inside the light bulb reacted through the metal filament. This corroded the filament and also caused dark store on the glass. Filling a light bulb v argon gas stays clear of these problems. That"s why modern light bulbs are filled v argon.

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Figure \(\PageIndex3\): modern-day light bulbs room filled with the noble gas argon to protect against corrosion the the filament inside.

Noble gases are likewise used to to fill the glass tubes of lighted indications like the one in the number below. Return noble gases are mslsec.comically nonreactive, their electrons have the right to be energized by sending out an electric existing through them. As soon as this happens, the electrons jump to a higher energy level. Once the electrons return to their original power level, they offer off power as light. Various noble gases offer off irradiate of different colors. Neon provides off a reddish-orange light, choose the word "Open" in the authorize below. Krypton provides off violet light and also xenon gives off blue light.

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Figure \(\PageIndex4\): indications like this one room filled v nobles gases prefer neon or xenon, which offer off light when energized.