Okay, helium balloons space light...but they"re no that light! The cool image listed below serves to make the point 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 among the lightest aspects in the routine table.

What room Noble Gases?

Noble gases room nonreactive, nonmetallic facets in group 18 that the regular table. Together you have the right to see in the regular table in the figure 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 also radon \(\left( \ceRn \right)\). All noble gases are colorless and odorless. They likewise 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 other elements.

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

yellowcomic.comical properties of Noble Gases

Noble gases room the the very least reactive that all well-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. However helium also has a full outer power level, because its only power level (energy level 1) can hold a best of two electrons. A full outer energy level is the many stable arrangement of electrons. As a result, noble gases can not become an ext stable by reacting with other elements and also gaining or shedding valence electrons. Therefore, noble gases room rarely associated in yellowcomic.comical reaction and virtually never form compounds with other elements.


Noble Gases and the Octet Rule

Because the noble gases are the least reactive of every elements, their eight valence electrons are provided as the standard for non-reactivity, and to describe how other elements interact. This is stated as the octet ("group the eight") rule. According to this rule, atoms react to form compounds that enable them to have a team of eight valence electrons prefer the noble gases. For example, sodium (with one valence electron) reacts v chlorine (with 7 valence electrons) to form the stable compound salt chloride (table salt). In this reaction, sodium donates an electron and also chlorine accepts it, giving each element an octet that valence electrons.


Some offers of Noble Gases

Have you ever before hadhelium balloons favor those in the elephant image? unequal a balloon filled through air, a balloon filled through helium requirements to be weighted under so that it won"t to rise away—although friend don"t need to use one elephant!

Early incandescent irradiate bulbs, favor the one pictured in the figure below, didn"t last an extremely long. The filaments quickly melted out. Back air was pumped the end of the bulb, the wasn"t a finish vacuum. Oxygen in the little amount of air remaining inside the light bulb reacted v the metal filament. This corroded the filament and caused dark store on the glass. Filling a irradiate bulb through argon gas avoids these problems. That"s why contemporary light bulbs are filled v argon.

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

Noble gases are also used to fill the glass tube of lighted indications like the one in the figure below. Although noble gases are yellowcomic.comically nonreactive, your electrons can be energized by sending an electric existing through them. When this happens, the electrons jump to a higher energy level. As soon as the electrons go back to their original energy level, they offer off power as light. Various noble gases provide off light of different colors. Neon gives off a reddish-orange light, choose the native "Open" in the authorize below. Krypton offers off violet light and also xenon provides 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 once energized.