Okay, helium balloons are light...however they"re not that light! The fanciful photo listed below serves to make the point that helium is one of the lightest facets. Helium belongs to a team of facets called the noble gases.

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

What are Noble Gases?

Noble gases are nonreenergetic, nonmetallic aspects in group 18 of the periodic table. As you deserve to check out in the routine table in the number 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 also radon (left( ceRn ight)). All noble gases are colorless and odormuch less. They also have low boiling points, which defines why they are all gases at room temperature. Radon, at the bottom of the team, is radioactive, so it constantly decays to various other elements.

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Figure (PageIndex2): Noble gases are in team 18 of the periodic table, in this instance the red column on the far appropriate.

slrfc.orgical Properties of Noble Gases

Noble gases are the leastern reactive of all recognized elements. Their external energy levels are full bereason they each have eight valence electrons. The just exemption is helium, which has just 2 electrons. But helium additionally has actually a full outer power level, bereason its only energy level (power level 1) deserve to hold a maximum of 2 electrons. A full outer power level is the many steady setup of electrons. As a result, noble gases cannot end up being even more secure by reacting via other elements and also getting or shedding valence electrons. Therefore, noble gases are seldom associated in slrfc.orgical reactions and also nearly never form compounds with various other facets.


Noble Gases and also the Octet Rule

Because the noble gases are the least reenergetic of all facets, their eight valence electrons are offered as the standard for non-reactivity, and to explain just how other facets connect. This is proclaimed as the octet ("group of eight") preeminence. According to this rule, atoms react to create compounds that allow them to have actually a group of eight valence electrons choose the noble gases. For instance, sodium (through one valence electron) reacts via chlorine (with salso valence electrons) to form the steady compound sodium chloride (table salt). In this reaction, sodium donates an electron and chlorine accepts it, offering each facet an octet of valence electrons.


Some Uses of Noble Gases

Have you ever hadhelium balloons favor those in the elephant image? Unfavor a balloon filled via air, a balloon filled through helium needs to be weighted down so that it will not float away—although you do not have to usage an elephant!

Early incandescent light bulbs, prefer the one pictured in the figure listed below, didn"t last very lengthy. The filaments easily burned out. Although air was pumped out of the bulb, it wasn"t a complete vacuum. Oxygen in the little amount of air continuing to be inside the light bulb reacted via the metal filament. This corroded the filament and brought about dark deposits on the glass. Filling a light bulb through argon gas stays clear of these problems. That"s why contemporary light bulbs are filled through argon.

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Figure (PageIndex3): Modern light bulbs are filled through the noble gas argon to proccasion corrosion of the filament inside.

Noble gases are also supplied to fill the glass tubes of lighted indicators like the one in the number listed below. Although noble gases are slrfc.orgically nonreenergetic, their electrons deserve to be energized by sfinishing an electric current with them. When this happens, the electrons jump to a higher energy level. When the electrons go back to their original power level, they provide off energy as light. Different noble gases give off light of different colors. Neon provides off a reddish-ovariety light, favor the word "Open" in the sign listed below. Krypton provides off violet light and xenon provides off blue light.

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Figure (PageIndex4): Signs prefer this one are filled via nobles gases favor neon or xenon, which give off light as soon as energized.