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

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Figure \(\PageIndex1\): Helium is among the lightest facets in the periodic table.

What room Noble Gases?

Noble gases room nonreactive, nonmetallic aspects in team 18 that the routine table. Together you can see in the periodic 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 \(\left( \ceRn \right)\). All noble gases room colorless and also odorless. They also have short boiling points, which describes why they are all gases at room temperature. Radon, at the bottom of the group, is radioactive, so the constantly decays to various other elements.

Figure \(\PageIndex2\): Noble gases are in team 18 of the routine table, in this situation the red column on the far right.

centregalilee.comical nature of Noble Gases

Noble gases are the the very least reactive of all well-known elements. Your outer power levels are full because they each have eight valence electrons. The only exception is helium, which has actually just two electrons. Yet helium additionally has a complete outer power level, due to the fact that its only power level (energy level 1) deserve to hold a preferably of 2 electrons. A complete outer energy level is the many stable setup of electrons. As a result, noble gases cannot become more stable by reaction with other elements and gaining or losing valence electrons. Therefore, noble gases space rarely involved in centregalilee.comical reactions and almost never kind compounds with other elements.

Noble Gases and also the Octet Rule

Because the noble gases space the least reactive of every elements, your eight valence electron are used as the traditional for non-reactivity, and to describe how other facets interact. This is declared as the octet ("group that eight") rule. According to this rule, atoms reaction to form compounds that permit them to have actually a group of eight valence electrons favor the noble gases. Because that example, sodium (with one valence electron) reacts through chlorine (with 7 valence electrons) to kind the secure compound sodium chloride (table salt). In this reaction, salt donates one electron and chlorine accepts it, providing each element an octet that valence electrons.

Some uses of Noble Gases

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

Early incandescent light bulbs, prefer the one pictured in the figure below, didn"t last really long. The filaments quickly shed out. Although air to be pumped the end of the bulb, the wasn"t a complete vacuum. Oxygen in the small amount that air staying inside the light bulb reacted v the steel filament. This corroded the filament and also caused dark store on the glass. Filling a light bulb with argon gas prevents these problems. That"s why contemporary light bulbs room filled with argon.

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

Noble gases are also used to to fill the glass tube of lighted indicators like the one in the figure below. Return noble gases are centregalilee.comically nonreactive, your electrons deserve to be energized by sending out an electric existing through them. As soon as this happens, the electrons jump to a greater energy level. When the electrons go back to their original energy level, they provide off energy as light. Different noble gases give off light of various colors. Neon provides off a reddish-orange light, like the indigenous "Open" in the sign below. Krypton offers off violet light and also xenon provides off blue light.

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Figure \(\PageIndex4\): signs like this one space filled v nobles gases like neon or xenon, which provide off light as soon as energized.