Okay, helium balloons are light...but they"re not that light! The fanciful image below serves to make the point that helium is just one of the lightest elements. Helium belongs come a group of aspects called the noble gases.

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

What room Noble Gases?

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

Figure (PageIndex2): Noble gases are in team 18 of the periodic table, in this case the red column on the much right.

bsci-ch.orgical properties of Noble Gases

Noble gases are the the very least reactive that all well-known elements. Their outer energy levels space full due to the fact that they each have eight valence electrons. The only exemption is helium, which has just two electrons. Yet helium additionally has a full outer power level, since its only power level (energy level 1) have the right to hold a maximum of 2 electrons. A complete outer energy level is the most stable arrangement of electrons. As a result, noble gases cannot become an ext stable by reacting with other elements and gaining or losing valence electrons. Therefore, noble gases are rarely affiliated in bsci-ch.orgical reactions and almost never kind compounds with other elements.

Noble Gases and the Octet Rule

Because the noble gases are the least reactive of all elements, their eight valence electrons are supplied as the standard for non-reactivity, and also to define how other elements interact. This is proclaimed as the octet ("group of eight") rule. According to this rule, atoms react to kind compounds that allow them to have actually a group of eight valence electrons prefer the noble gases. For example, sodium (with one valence electron) reacts v chlorine (with 7 valence electrons) to type the steady compound salt chloride (table salt). In this reaction, salt donates an electron and also chlorine accepts it, offering each element an octet of valence electrons.

Some provides of Noble Gases

Have you ever before hadhelium balloons favor those in the elephant image? uneven a balloon filled with air, a balloon filled v helium needs to be weighted under so the it won"t float away—although girlfriend don"t have to use one elephant!

Early incandescent irradiate bulbs, like the one pictured in the figure below, didn"t last very long. The filaments quickly burned out. Return air to be pumped out of the bulb, the wasn"t a finish vacuum. Oxygen in the little amount of air continuing to be inside the light pear reacted v the steel filament. This corroded the filament and caused dark shop on the glass. Pour it until it is full a irradiate bulb with argon gas stays clear of these problems. That"s why contemporary light bulbs space filled with argon.

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

Noble gases are also used to to fill the glass pipe of lighted indicators like the one in the figure below. Return noble gases are bsci-ch.orgically nonreactive, their electrons deserve to be energized by sending out an electric existing through them. Once this happens, the electrons run to a greater energy level. When the electrons return to their original power level, they provide off energy as light. Different noble gases offer off light of various colors. Neon offers off a reddish-orange light, prefer the native "Open" in the sign below. Krypton offers off violet light and xenon offers off blue light.

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Figure (PageIndex4): signs like this one room filled with nobles gases favor neon or xenon, which provide off light when energized.