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

You are watching: Noble gases are the least reactive elements on the periodic table

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

What are Noble Gases?

Noble gases room nonreactive, nonmetallic elements in group 18 of the regular table. Together you have the right to see in the routine table in the number below, noble gases include 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 are colorless and also odorless. They also have short boiling points, which defines why they are all gases at room temperature. Radon, in ~ the bottom that the group, is radioactive, so it constantly decays to various other elements.

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

lifwynnfoundation.orgical nature of Noble Gases

Noble gases room the the very least reactive the all recognized elements. Their outer energy levels are full since they each have eight valence electrons. The only exemption is helium, which has just two electrons. However helium also has a complete outer energy level, because its only energy level (energy level 1) have the right to hold a preferably of 2 electrons. A complete outer power level is the most stable plan of electrons. As a result, noble gases cannot become an ext stable by reaction with various other elements and also gaining or shedding valence electrons. Therefore, noble gases space rarely involved in lifwynnfoundation.orgical reaction and practically never form compounds with various other elements.

Noble Gases and also the Octet Rule

Because the noble gases room the least reactive of all elements, your eight valence electron are used as the typical for non-reactivity, and also to define how other elements interact. This is proclaimed as the octet ("group the eight") rule. According to this rule, atoms reaction to form compounds that allow them to have a team of eight valence electrons prefer the noble gases. For example, sodium (with one valence electron) reacts with chlorine (with seven valence electrons) to kind the secure compound salt chloride (table salt). In this reaction, sodium donates one electron and chlorine accepts it, giving each element an octet the valence electrons.

Some provides of Noble Gases

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

Early incandescent light bulbs, favor the one pictured in the figure below, didn"t last an extremely long. The filaments quickly shed out. Return air was pumped out of the bulb, that wasn"t a complete vacuum. Oxygen in the little amount that air continuing to be inside the light bulb reacted through the steel filament. This corroded the filament and also caused dark shop on the glass. Filling a irradiate bulb through argon gas avoids these problems. That"s why modern-day light bulbs room filled through argon.

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

Noble gases are also used to to fill the glass pipe of lighted indicators like the one in the number below. Although noble gases are lifwynnfoundation.orgically nonreactive, your electrons can be energized by sending out an electric existing through them. When this happens, the electrons run to a higher energy level. As soon as the electrons go back to their original power level, they offer off power as light. Various noble gases offer off light of various colors. Neon gives off a reddish-orange light, like the native "Open" in the sign below. Krypton offers off violet light and also xenon offers off blue light.

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