Okay, helium balloons space light...but they"re not that light! The cool image listed below serves to make the allude that helium is just one of the lightest elements. Helium belongs to a team of elements called the noble gases.

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Figure (PageIndex1): Helium is just one of the lightest elements in the routine table.

What are Noble Gases?

Noble gases room nonreactive, nonmetallic elements in team 18 of the routine table. Together you have the right to see in the routine table in the figure below, noble gases include helium (left( ceHe ight)), neon (left( ceNe ight)), argon (left( ceAr ight)), krypton (left( ceKr ight)), xenon (left( ceXe ight)), and radon (left( ceRn ight)). All noble gases are colorless and odorless. They also have short boiling points, which explains why they space all gases at room temperature. Radon, at the bottom of the group, is radioactive, so it constantly decays to other elements.

Figure (PageIndex2): Noble gases space in group 18 the the regular table, in this case the red tower on the much right.

lungemine.comical properties of Noble Gases

Noble gases room the least reactive of all known elements. Your outer power levels space full because they each have actually eight valence electrons. The only exception is helium, which has actually just two electrons. But helium additionally has a complete outer power level, due to the fact that its only power level (energy level 1) can hold a best of 2 electrons. A complete outer power level is the many stable plan of electrons. Together a result, noble gases cannot become an ext stable by reacting with various other elements and also gaining or shedding valence electrons. Therefore, noble gases are rarely involved in lungemine.comical reactions and virtually never kind compounds with various other elements.

Noble Gases and also the Octet Rule

Because the noble gases space the least reactive of every elements, your eight valence electrons are used as the conventional for non-reactivity, and also to explain how other facets interact. This is stated as the octet ("group of eight") rule. Follow to this rule, atoms react to kind compounds that allow them to have actually a group of eight valence electrons favor the noble gases. Because that example, salt (with one valence electron) reacts with chlorine (with 7 valence electrons) to form the steady compound salt chloride (table salt). In this reaction, sodium donates one electron and chlorine accepts it, giving each facet an octet of valence electrons.

Some provides of Noble Gases

Have you ever hadhelium balloons like those in the elephant image? unequal a balloon filled through air, a balloon filled v helium needs to it is in weighted under so that it won"t rise away—although girlfriend don"t need to use one elephant!

Early incandescent light bulbs, prefer the one pictured in the figure below, didn"t last an extremely long. The filaments quickly shed out. Although air to be pumped out of the bulb, that wasn"t a complete vacuum. Oxygen in the small amount that air continuing to be inside the light bulb reacted with the metal filament. This corroded the filament and caused dark store on the glass. Pour it until it is full a irradiate bulb with argon gas prevents these problems. That"s why modern-day light bulbs room filled v argon.

Figure (PageIndex3): contemporary light bulbs room filled v the noble gas argon to prevent corrosion the the filament inside.

Noble gases are likewise used to to fill the glass tube of lighted indications like the one in the figure below. Return noble gases room lungemine.comically nonreactive, your electrons have the right to be energized by sending out an electric present through them. When this happens, the electrons jump to a higher energy level. As soon as the electrons go back to their original power level, they give off power as light. Different noble gases provide off light of different colors. Neon offers off a reddish-orange light, favor the indigenous "Open" in the sign below. Krypton gives off violet light and also xenon gives off blue light.

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Figure (PageIndex4): indications like this one space filled with nobles gases prefer neon or xenon, which provide off light when energized.