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

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

What are Noble Gases?

Noble gases are nonreactive, nonmetallic facets in team 18 of the routine table. As you have the right to watch in the regular table in the number listed 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 radon (left( ceRn ight)). All noble gases are colormuch less and also odormuch less. They also have actually low boiling points, which describes why they are all gases at room temperature. Radon, at the bottom of the group, is radioactive, so it constantly decays to various other aspects.

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

muzic-ivan.infoical Properties of Noble Gases

Noble gases are the leastern reactive of all well-known facets. Their external energy levels are complete bereason they each have eight valence electrons. The only exception is helium, which has just two electrons. But helium also has actually a complete outer power level, because its only power level (energy level 1) can host a maximum of two electrons. A complete outer energy level is the the majority of stable plan of electrons. As an outcome, noble gases cannot end up being even more secure by reacting with various other aspects and also gaining or shedding valence electrons. As such, noble gases are rarely associated in muzic-ivan.infoical reactions and also almost never before create compounds through other elements.


Noble Gases and the Octet Rule

Since the noble gases are the leastern reenergetic of all elements, their eight valence electrons are offered as the typical for non-retask, and to describe exactly how various other facets communicate. This is declared as the octet ("group of eight") preeminence. According to this ascendancy, atoms react to form compounds that permit them to have a team of eight valence electrons prefer the noble gases. For example, sodium (through one valence electron) reacts via chlorine (via seven valence electrons) to form the secure compound sodium chloride (table salt). In this reactivity, sodium donates an electron and also chlorine accepts it, providing each aspect an octet of valence electrons.


Some Uses of Noble Gases

Have you ever before hadhelium balloons favor those in the elephant image? Unchoose a balloon filled with air, a balloon filled via helium requirements to be weighted down so that it won"t float away—although you don"t have to use an elephant!

Early incandescent light bulbs, like the one pictured in the figure below, didn"t last exceptionally lengthy. The filaments conveniently melted out. Although air was pumped out of the bulb, it wasn"t a complete vacuum. Oxygen in the little amount of air remaining inside the light bulb reacted through the metal filament. This corroded the filament and resulted in dark deposits on the glass. Filling a light bulb through argon gas prevents these problems. That"s why modern light bulbs are filled with argon.

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

Noble gases are likewise offered to fill the glass tubes of lighted signs favor the one in the figure below. Although noble gases are muzic-ivan.infoically nonreenergetic, their electrons can be energized by sfinishing an electrical existing with them. When this happens, the electrons jump to a greater energy level. When the electrons return to their original power level, they offer off energy as light. Different noble gases offer off light of various colors. Neon provides off a reddish-ovariety light, like the word "Open" in the sign listed below. Krypton gives off violet light and xenon provides off blue light.

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