Helium - Revision history

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	[[Category:Done ~~2015~~-09-05]]		[[Category:Done 2016-12-31]]
	[[File:HELIUM.png\|200px\|thumb\|Figure 1. Helium with [[atomic number]] of 2 and [[atomic weight]] of 4.002602.<ref>Information from Jefferson Lab [Online], Available: http://education.jlab.org/itselemental/ele002.html</ref>]]		[[File:HELIUM.png\|200px\|thumb\|Figure 1. Helium with [[atomic number]] of 2 and [[atomic weight]] of 4.002602.<ref>Information from Jefferson Lab [Online], Available: http://education.jlab.org/itselemental/ele002.html</ref>]]
	<onlyinclude>'''Helium''' is the 2<sup>nd</sup> [[element]] on the [[periodic table of elements\|periodic table]], and it is the 2<sup>nd</sup> most abundant element in the universe; making up 23% of the total [[mass]] of all elements (some sources go as high as 25%).</onlyinclude><ref>Periodic Table. (Accessed Sept. 2, 2015). ''Abundance in the Universe of the Elements'' [Online], Available: http://periodictable.com/Properties/A/UniverseAbundance.v.html</ref><ref name=hyp2>Hyperphysics. (Accessed Sept. 2, 2015). ''Hydrogen-Helium Abundance'' [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/astro/hydhel.html#c1</ref> Helium was discovered in the [[Sun]] before it was found on Earth, when astronomers were analyzing a solar eclipse in 1868. Because of this, it was suitably named helium after the Greek god of the Sun, Helios.<ref name=jeff>Jefferson Lab. (Accessed Sept. 2, 2015). ''The Element Helium'' [Online], Available: http://education.jlab.org/itselemental/ele002.html</ref>		<onlyinclude>'''Helium''' is the 2<sup>nd</sup> [[element]] on the [[periodic table of elements\|periodic table]], and it is the 2<sup>nd</sup> most abundant element in the universe; making up 23% of the total [[mass]] of all elements (some sources go as high as 25%).</onlyinclude><ref>Periodic Table. (Accessed Sept. 2, 2015). ''Abundance in the Universe of the Elements'' [Online], Available: http://periodictable.com/Properties/A/UniverseAbundance.v.html</ref><ref name=hyp2>Hyperphysics. (Accessed Sept. 2, 2015). ''Hydrogen-Helium Abundance'' [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/astro/hydhel.html#c1</ref> Helium was discovered in the [[Sun]] before it was found on Earth, when astronomers were analyzing a solar eclipse in 1868. Because of this, it was suitably named helium after the Greek god of the Sun, Helios.<ref name=jeff>Jefferson Lab. (Accessed Sept. 2, 2015). ''The Element Helium'' [Online], Available: http://education.jlab.org/itselemental/ele002.html</ref>
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	Helium is found naturally on Earth due to the [[radioactive decay]] of elements ~~within the~~ [[~~cross section of the Earth\|Earth's layers~~]]. Some elements go through [[alpha decay]] in which they emit an alpha particle, which is merely a helium [[nucleus]]. When this nucleus captures two [[electron]]s, it becomes elemental helium.<ref name=jeff/>		Helium is found naturally on Earth due to the [[radioactive decay]] of elements trapped underground (often in [[natural gas]] mines in the United States). Some elements go through [[alpha decay]] in which they emit an alpha particle, which is merely a helium [[nucleus]]. When this nucleus captures two [[electron]]s, it becomes elemental helium.<ref name=jeff/>

	Elemental helium does not [[chemical bond\|chemically bond]] with other elements because it is inert, meaning its [[valence and core electrons\|valence shell]] is completely full. Therefore there are no known compounds of helium ~~on Earth or~~ in the ~~universe~~.		Elemental helium does not [[chemical bond\|chemically bond]] with other elements because it is inert, meaning its [[valence and core electrons\|valence shell]] is completely full. Therefore there are no known compounds of helium; even in the laboratory people have never been able to get helium chemically react with anything.

	==Helium and the Big Bang==		==Helium and the Big Bang==
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	==Uses of Helium==		==Uses of Helium==

	Helium is very useful in society, ~~all the way from the common person to the~~ specialized ~~scientists~~.		Helium is very useful in society, including specialized scientific experiments, medical procedures and even party balloons.

	It is used for the inflation of balloons due to its low [[density]]. It is less dense than [[air]], so it naturally rises due to [http://hyperphysics.phy-astr.gsu.edu/hbase/pbuoy.html buoyant forces], making it ideal for party or weather balloons.<ref name=rsc>Royal Society of Chemistry. (Accessed Sept. 2, 2015). ''Helium'' [Online], Available: http://www.rsc.org/periodic-table/element/2/helium</ref> This is ~~also the reason why someone~~'s ~~voice is higher pitched~~ when helium ~~is inhaled~~.<ref>Scientific American. (Accessed Sept. 2, 2015). ''Why does inhaling helium make one's voice sound strange?'' [Online], Available: http://www.scientificamerican.com/article/why-does-inhaling-helium/</ref>		It is used for the inflation of balloons due to its low [[density]]. It is less dense than [[air]], so it naturally rises due to [http://hyperphysics.phy-astr.gsu.edu/hbase/pbuoy.html buoyant forces], making it ideal for party or weather balloons.<ref name=rsc>Royal Society of Chemistry. (Accessed Sept. 2, 2015). ''Helium'' [Online], Available: http://www.rsc.org/periodic-table/element/2/helium</ref> This low mass means that the [[speed of sound]] is quite a bit faster, and that's why people sounds strange when they've inhaled helium.<ref>Scientific American. (Accessed Sept. 2, 2015). ''Why does inhaling helium make one's voice sound strange?'' [Online], Available: http://www.scientificamerican.com/article/why-does-inhaling-helium/</ref> Inhaling helium can be dangerous as it displaces [[oxygen]], meaning that people can suffocate from breathing in helium, so be careful!

	Liquid helium provides the most practical means for achieving temperatures lower than [[kelvin\|20 K]], ideal for [[superconductor]] applications and other cooling systems like the Large Hadron Collider (LHC).<ref name=hyp1/> MRI scanners are one type of superconducting application that use liquid helium, since their large superconducting [[magnet]]s must be cooled to low temperatures.<Ref name=rsc/>		Liquid helium provides the most practical means for achieving temperatures lower than [[kelvin\|20 K]], ideal for [[superconductor]] applications and other cooling systems like the [http://home.cern/topics/large-hadron-collider Large Hadron Collider (LHC)].<ref name=hyp1/> MRI scanners are one type of superconducting application that use liquid helium, since their large superconducting [[magnet]]s must be cooled to low temperatures.<Ref name=rsc/>

	Due to its inert properties, it is used as a protective atmosphere for [[semiconductor]]s and fibre optics~~, and is also used~~ to detect leaks in ~~vacuum~~ systems.<Ref name=rsc/>		Due to its inert properties (helium doesn't chemically react with anything), it is used as a protective atmosphere for [[semiconductor]]s and [[fibre optics]]. Helium's small diameter (smaller than any other chemically stable substance) makes it perfect to detect leaks in systems kept at very low pressure (sometimes as low as a billionth of an atmosphere).<Ref name=rsc/>

			==Video==
			The video below is from the University of Nottingham's [http://www.periodicvideos.com/ periodic videos project].<ref>See more videos from the University of Nottingham on different elements here: http://www.periodicvideos.com/</ref> They have created a complete suite of short videos on every element on the [[periodic table of elements]].

			<html>
			<iframe width="816" height="459" src="https://www.youtube.com/embed/a8FJEiI5e6Q" frameborder="0" allowfullscreen></iframe>
			</html>

	==References==		==References==
	{{reflist}}		{{reflist}}[[Category:Uploaded]]

J.williams: 1 revision imported

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Jmdonev at 17:09, 3 September 2015

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[[Category:Done 2015-09-05]]
[[File:HELIUM.png|200px|thumb|Figure 1. Helium with [[atomic number]] of 2 and [[atomic weight]] of 4.002602.<ref>Information from Jefferson Lab [Online], Available: http://education.jlab.org/itselemental/ele002.html</ref>]]
<onlyinclude>'''Helium''' is the 2nd [[element]] on the [[periodic table of elements|periodic table]], and it is the 2nd most abundant element in the universe; making up 23% of the total [[mass]] of all elements (some sources go as high as 25%).</onlyinclude><ref>Periodic Table. (Accessed Sept. 2, 2015). ''Abundance in the Universe of the Elements'' [Online], Available: http://periodictable.com/Properties/A/UniverseAbundance.v.html</ref><ref name=hyp2>Hyperphysics. (Accessed Sept. 2, 2015). ''Hydrogen-Helium Abundance'' [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/astro/hydhel.html#c1</ref> Helium was discovered in the [[Sun]] before it was found on Earth, when astronomers were analyzing a solar eclipse in 1868. Because of this, it was suitably named helium after the Greek god of the Sun, Helios.<ref name=jeff>Jefferson Lab. (Accessed Sept. 2, 2015). ''The Element Helium'' [Online], Available: http://education.jlab.org/itselemental/ele002.html</ref>

Some properties of helium include:<ref name=hyp1>Hyperphysics. (Accessed Sept. 2, 2015). ''Helium'' [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/he.html</ref>

{| class="wikitable"
|-
| '''[[Atomic weight]]''' || 4.002602
|-
| '''[[Density]]''' (at 0oC) || .0001787 [[gram|g]]/[[meter|cm3]]
|-
| '''[[Boiling point]]''' || 4.215 [[Kelvin|K]]
|-
| '''[[Melting point]]''' || 0.95 K
|}

Helium is found naturally on Earth due to the [[radioactive decay]] of elements within the [[cross section of the Earth|Earth's layers]]. Some elements go through [[alpha decay]] in which they emit an alpha particle, which is merely a helium [[nucleus]]. When this nucleus captures two [[electron]]s, it becomes elemental helium.<ref name=jeff/>

Elemental helium does not [[chemical bond|chemically bond]] with other elements because it is inert, meaning its [[valence and core electrons|valence shell]] is completely full. Therefore there are no known compounds of helium on Earth or in the universe.

==Helium and the Big Bang==

The large abundances of helium found in the universe is evidence for the Big Bang theory. When the universe was dense and hot, [[proton]]s and [[neutron]]s were able to exist in the same abundance (first section of Figure 2): this is because neutrons naturally [[beta decay]] into a proton and electron, however the high [[temperature]] allowed for the recombination of these into a neutron.<ref name=hyp2/>

When the universe expanded it cooled off, meaning that this recombination was no longer possible, and neutrons began to decay. However, due to the stability of the [[deuterium#The Deuteron|deuteron]] (a neutron bound to a proton), this decay was thwarted, and neutrons were able to exist much longer than in their free state. The deuterons were then able to [[nuclear fusion|fuse]] into helium at a later time, explaining the abundance observed today. Figure 2 below demonstrates this process (the 74% of hydrogen and 26% of helium are their relative mass abundance, not the abundance compared to all other elements).

[[File:bigbanghelium.gif|700px|thumb|center|Figure 2. "Big bang nucleosynthesis" explains the abundances of helium seen in the universe today. Refer to the text above for a more detailed explanation of this image.<ref name=hyp2/>]]

==Uses of Helium==

Helium is very useful in society, all the way from the common person to the specialized scientists.

It is used for the inflation of balloons due to its low [[density]]. It is less dense than [[air]], so it naturally rises due to [http://hyperphysics.phy-astr.gsu.edu/hbase/pbuoy.html buoyant forces], making it ideal for party or weather balloons.<ref name=rsc>Royal Society of Chemistry. (Accessed Sept. 2, 2015). ''Helium'' [Online], Available: http://www.rsc.org/periodic-table/element/2/helium</ref> This is also the reason why someone's voice is higher pitched when helium is inhaled.<ref>Scientific American. (Accessed Sept. 2, 2015). ''Why does inhaling helium make one's voice sound strange?'' [Online], Available: http://www.scientificamerican.com/article/why-does-inhaling-helium/</ref>

Liquid helium provides the most practical means for achieving temperatures lower than [[kelvin|20 K]], ideal for [[superconductor]] applications and other cooling systems like the Large Hadron Collider (LHC).<ref name=hyp1/> MRI scanners are one type of superconducting application that use liquid helium, since their large superconducting [[magnet]]s must be cooled to low temperatures.<Ref name=rsc/>

Due to its inert properties, it is used as a protective atmosphere for [[semiconductor]]s and fibre optics, and is also used to detect leaks in vacuum systems.<Ref name=rsc/>

==References==
{{reflist}}