He

He[edit | edit source]

He is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.

History[edit | edit source]

Helium was first detected in the solar spectrum by Jules Janssen and Norman Lockyer in 1868. It was later isolated on Earth by William Ramsay, Per Teodor Cleve, and Nils Abraham Langlet in 1895.

Properties[edit | edit source]

Helium is the second lightest and second most abundant element in the observable universe, being present in about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is due to the very high nuclear binding energy (per nucleon) of helium-4, with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay.

Isotopes[edit | edit source]

There are two stable isotopes of helium: helium-3 and helium-4. Helium-4 is by far the most common, making up about 99.99986% of the helium on Earth. Helium-3 is much rarer and is sought after for use in cryogenics and nuclear fusion research.

Applications[edit | edit source]

Helium has many applications, including in cryogenics, particularly in the cooling of superconducting magnets, such as those used in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) spectrometers. It is also used as a protective gas in arc welding, in the production of semiconductors, and as a lifting gas in balloons and airships.

Occurrence[edit | edit source]

Helium is found in large amounts in natural gas fields, particularly in the United States, which is the world's largest supplier. It is extracted through a process of fractional distillation.

Safety[edit | edit source]

Helium is non-toxic and inert, making it safe to use in many applications. However, inhaling helium can be dangerous as it can displace oxygen needed for normal respiration.

References[edit | edit source]

External links[edit | edit source]

Group	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
	Hydrogen & alkali metals	Alkaline earth metals											Triels	Tetrels	Pnictogens	Chalcogens	Halogens	Noble gases
Period 1	[[ hydrogen \|Hydrogen1H1.0080]]																	[[ helium \|Helium2He4.0026]]
2	[[ lithium \|Lithium3Li6.94]]	[[ beryllium \|Beryllium4Be9.0122]]											[[ boron \|Boron5B10.81]]	[[ carbon \|Carbon6C12.011]]	[[ nitrogen \|Nitrogen7N14.007]]	[[ oxygen \|Oxygen8O15.999]]	[[ fluorine \|Fluorine9F18.998]]	[[ neon \|Neon10Ne20.180]]
3	[[ sodium \|Sodium11Na22.990]]	[[ magnesium \|Magnesium12Mg24.305]]											[[ aluminium \|Aluminium13Al26.982]]	[[ silicon \|Silicon14Si28.085]]	[[ phosphorus\|Phosphorus15P30.974]]	[[ sulfur \|Sulfur16S32.06]]	[[ chlorine \|Chlorine17Cl35.45]]	[[ argon \|Argon18Ar39.95]]
4	[[ potassium \|Potassium19K39.098]]	[[ calcium \|Calcium20Ca40.078]]	[[ scandium \|Scandium21Sc44.956]]	[[ titanium \|Titanium22Ti47.867]]	[[ vanadium \|Vanadium23V50.942]]	[[ chromium \|Chromium24Cr51.996]]	[[ manganese \|Manganese25Mn54.938]]	[[ iron \|Iron26Fe55.845]]	[[ cobalt \|Cobalt27Co58.933]]	[[ nickel \|Nickel28Ni58.693]]	[[ copper \|Copper29Cu63.546]]	[[ zinc \|Zinc30Zn65.38]]	[[ gallium \|Gallium31Ga69.723]]	[[ germanium \|Germanium32Ge72.630]]	[[ arsenic \|Arsenic33As74.922]]	[[ selenium \|Selenium34Se78.971]]	[[ bromine \|Bromine35Br79.904]]	[[ krypton \|Krypton36Kr83.798]]
5	[[ rubidium \|Rubidium37Rb85.468]]	[[ strontium \|Strontium38Sr87.62]]	[[ yttrium \|Yttrium39Y88.906]]	[[ zirconium \|Zirconium40Zr91.224]]	[[ niobium \|Niobium41Nb92.906]]	[[ molybdenum\|Molybdenum42Mo95.95]]	[[ technetium\|Technetium43Tc[97]]]	[[ ruthenium \|Ruthenium44Ru101.07]]	[[ rhodium \|Rhodium45Rh102.91]]	[[ palladium \|Palladium46Pd106.42]]	[[ silver \|Silver47Ag107.87]]	[[ cadmium \|Cadmium48Cd112.41]]	[[ indium \|Indium49In114.82]]	[[ tin \|Tin50Sn118.71]]	[[ antimony \|Antimony51Sb121.76]]	[[ tellurium \|Tellurium52Te127.60]]	[[ iodine \|Iodine53I126.90]]	[[ xenon \|Xenon54Xe131.29]]
6	[[ caesium \|Caesium55Cs132.91]]	[[ barium \|Barium56Ba137.33]]	[[ lutetium \|Lutetium71Lu174.97]]	[[ hafnium \|Hafnium72Hf178.49]]	[[ tantalum \|Tantalum73Ta180.95]]	[[ tungsten \|Tungsten74W183.84]]	[[ rhenium \|Rhenium75Re186.21]]	[[ osmium \|Osmium76Os190.23]]	[[ iridium \|Iridium77Ir192.22]]	[[ platinum \|Platinum78Pt195.08]]	[[ gold \|Gold79Au196.97]]	[[ Mercury (element)\|Mercury80Hg200.59]]	[[ thallium \|Thallium81Tl204.38]]	[[ lead \|Lead82Pb207.2]]	[[ bismuth \|Bismuth83Bi208.98]]	[[ polonium \|Polonium84Po[209]]]	[[ astatine \|Astatine85At[210]]]	[[ radon \|Radon86Rn[222]]]
7	[[ francium \|Francium87Fr[223]]]	[[ radium \|Radium88Ra[226]]]	[[ lawrencium \|Lawrencium103Lr[266]]]	[[ rutherfordium\|Rutherfordium104Rf[267]]]	[[ dubnium \|Dubnium105Db[268]]]	[[ seaborgium \|Seaborgium106Sg[269]]]	[[ bohrium \|Bohrium107Bh[270]]]	[[ hassium \|Hassium108Hs[269]]]	[[ meitnerium \|Meitnerium109Mt[278]]]	[[ darmstadtium \|Darmstadtium110Ds[281]]]	[[ roentgenium \|Roentgenium111Rg[282]]]	[[ copernicium \|Copernicium112Cn[285]]]	[[ nihonium \|Nihonium113Nh[286]]]	[[ flerovium \|Flerovium114Fl[289]]]	[[ moscovium \|Moscovium115Mc[290]]]	[[ livermorium \|Livermorium116Lv[293]]]	[[ tennessine \|Tennessine117Ts[294]]]	[[ oganesson \|Oganesson118Og[294]]]

			[[ lanthanum \|Lanthanum57La138.91]]	[[ cerium \|Cerium58Ce140.12]]	[[ praseodymium\|Praseodymium59Pr140.91]]	[[ neodymium \|Neodymium60Nd144.24]]	[[ promethium \|Promethium61Pm[145]]]	[[ samarium \|Samarium62Sm150.36]]	[[ europium \|Europium63Eu151.96]]	[[ gadolinium \|Gadolinium64Gd157.25]]	[[ terbium \|Terbium65Tb158.93]]	[[ dysprosium \|Dysprosium66Dy162.50]]	[[ holmium \|Holmium67Ho164.93]]	[[ erbium \|Erbium68Er167.26]]	[[ thulium \|Thulium69Tm168.93]]	[[ ytterbium \|Ytterbium70Yb173.05]]
			[[ actinium \|Actinium89Ac[227]]]	[[ thorium \|Thorium90Th232.04]]	[[ protactinium\|Protactinium91Pa231.04]]	[[ uranium \|Uranium92U238.03]]	[[ neptunium \|Neptunium93Np[237]]]	[[ plutonium \|Plutonium94Pu[244]]]	[[ americium \|Americium95Am[243]]]	[[ curium \|Curium96Cm[247]]]	[[ berkelium \|Berkelium97Bk[247]]]	[[ californium \|Californium98Cf[251]]]	[[ einsteinium \|Einsteinium99Es[252]]]	[[ fermium \|Fermium100Fm[257]]]	[[ mendelevium\|Mendelevium101Md[258]]]	[[ nobelium \|Nobelium102No[259]]]

Primordial From decay Synthetic Border shows natural occurrence of the element

Standard atomic weight A_{r, std}(E)^[1]

Ca: 40.078

— Abridged value (uncertainty omitted here)^[2]

Po: [209] — mass number of the most stable isotope

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[CIAAW2013-1] Cite error: Invalid <ref> tag; no text was provided for refs named CIAAW2013

[CIAAW2021-2] Cite error: Invalid <ref> tag; no text was provided for refs named CIAAW2021

[1]

[2]

Group	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
	Hydrogen & alkali metals	Alkaline earth metals											Triels	Tetrels	Pnictogens	Chalcogens	Halogens	Noble gases
Period 1	[[ hydrogen \|Hydrogen1H1.0080]]																	[[ helium \|Helium2He4.0026]]
2	[[ lithium \|Lithium3Li6.94]]	[[ beryllium \|Beryllium4Be9.0122]]											[[ boron \|Boron5B10.81]]	[[ carbon \|Carbon6C12.011]]	[[ nitrogen \|Nitrogen7N14.007]]	[[ oxygen \|Oxygen8O15.999]]	[[ fluorine \|Fluorine9F18.998]]	[[ neon \|Neon10Ne20.180]]
3	[[ sodium \|Sodium11Na22.990]]	[[ magnesium \|Magnesium12Mg24.305]]											[[ aluminium \|Aluminium13Al26.982]]	[[ silicon \|Silicon14Si28.085]]	[[ phosphorus\|Phosphorus15P30.974]]	[[ sulfur \|Sulfur16S32.06]]	[[ chlorine \|Chlorine17Cl35.45]]	[[ argon \|Argon18Ar39.95]]
4	[[ potassium \|Potassium19K39.098]]	[[ calcium \|Calcium20Ca40.078]]	[[ scandium \|Scandium21Sc44.956]]	[[ titanium \|Titanium22Ti47.867]]	[[ vanadium \|Vanadium23V50.942]]	[[ chromium \|Chromium24Cr51.996]]	[[ manganese \|Manganese25Mn54.938]]	[[ iron \|Iron26Fe55.845]]	[[ cobalt \|Cobalt27Co58.933]]	[[ nickel \|Nickel28Ni58.693]]	[[ copper \|Copper29Cu63.546]]	[[ zinc \|Zinc30Zn65.38]]	[[ gallium \|Gallium31Ga69.723]]	[[ germanium \|Germanium32Ge72.630]]	[[ arsenic \|Arsenic33As74.922]]	[[ selenium \|Selenium34Se78.971]]	[[ bromine \|Bromine35Br79.904]]	[[ krypton \|Krypton36Kr83.798]]
5	[[ rubidium \|Rubidium37Rb85.468]]	[[ strontium \|Strontium38Sr87.62]]	[[ yttrium \|Yttrium39Y88.906]]	[[ zirconium \|Zirconium40Zr91.224]]	[[ niobium \|Niobium41Nb92.906]]	[[ molybdenum\|Molybdenum42Mo95.95]]	[[ technetium\|Technetium43Tc[97]]]	[[ ruthenium \|Ruthenium44Ru101.07]]	[[ rhodium \|Rhodium45Rh102.91]]	[[ palladium \|Palladium46Pd106.42]]	[[ silver \|Silver47Ag107.87]]	[[ cadmium \|Cadmium48Cd112.41]]	[[ indium \|Indium49In114.82]]	[[ tin \|Tin50Sn118.71]]	[[ antimony \|Antimony51Sb121.76]]	[[ tellurium \|Tellurium52Te127.60]]	[[ iodine \|Iodine53I126.90]]	[[ xenon \|Xenon54Xe131.29]]
6	[[ caesium \|Caesium55Cs132.91]]	[[ barium \|Barium56Ba137.33]]	[[ lutetium \|Lutetium71Lu174.97]]	[[ hafnium \|Hafnium72Hf178.49]]	[[ tantalum \|Tantalum73Ta180.95]]	[[ tungsten \|Tungsten74W183.84]]	[[ rhenium \|Rhenium75Re186.21]]	[[ osmium \|Osmium76Os190.23]]	[[ iridium \|Iridium77Ir192.22]]	[[ platinum \|Platinum78Pt195.08]]	[[ gold \|Gold79Au196.97]]	[[ Mercury (element)\|Mercury80Hg200.59]]	[[ thallium \|Thallium81Tl204.38]]	[[ lead \|Lead82Pb207.2]]	[[ bismuth \|Bismuth83Bi208.98]]	[[ polonium \|Polonium84Po[209]]]	[[ astatine \|Astatine85At[210]]]	[[ radon \|Radon86Rn[222]]]
7	[[ francium \|Francium87Fr[223]]]	[[ radium \|Radium88Ra[226]]]	[[ lawrencium \|Lawrencium103Lr[266]]]	[[ rutherfordium\|Rutherfordium104Rf[267]]]	[[ dubnium \|Dubnium105Db[268]]]	[[ seaborgium \|Seaborgium106Sg[269]]]	[[ bohrium \|Bohrium107Bh[270]]]	[[ hassium \|Hassium108Hs[269]]]	[[ meitnerium \|Meitnerium109Mt[278]]]	[[ darmstadtium \|Darmstadtium110Ds[281]]]	[[ roentgenium \|Roentgenium111Rg[282]]]	[[ copernicium \|Copernicium112Cn[285]]]	[[ nihonium \|Nihonium113Nh[286]]]	[[ flerovium \|Flerovium114Fl[289]]]	[[ moscovium \|Moscovium115Mc[290]]]	[[ livermorium \|Livermorium116Lv[293]]]	[[ tennessine \|Tennessine117Ts[294]]]	[[ oganesson \|Oganesson118Og[294]]]

			[[ lanthanum \|Lanthanum57La138.91]]	[[ cerium \|Cerium58Ce140.12]]	[[ praseodymium\|Praseodymium59Pr140.91]]	[[ neodymium \|Neodymium60Nd144.24]]	[[ promethium \|Promethium61Pm[145]]]	[[ samarium \|Samarium62Sm150.36]]	[[ europium \|Europium63Eu151.96]]	[[ gadolinium \|Gadolinium64Gd157.25]]	[[ terbium \|Terbium65Tb158.93]]	[[ dysprosium \|Dysprosium66Dy162.50]]	[[ holmium \|Holmium67Ho164.93]]	[[ erbium \|Erbium68Er167.26]]	[[ thulium \|Thulium69Tm168.93]]	[[ ytterbium \|Ytterbium70Yb173.05]]
			[[ actinium \|Actinium89Ac[227]]]	[[ thorium \|Thorium90Th232.04]]	[[ protactinium\|Protactinium91Pa231.04]]	[[ uranium \|Uranium92U238.03]]	[[ neptunium \|Neptunium93Np[237]]]	[[ plutonium \|Plutonium94Pu[244]]]	[[ americium \|Americium95Am[243]]]	[[ curium \|Curium96Cm[247]]]	[[ berkelium \|Berkelium97Bk[247]]]	[[ californium \|Californium98Cf[251]]]	[[ einsteinium \|Einsteinium99Es[252]]]	[[ fermium \|Fermium100Fm[257]]]	[[ mendelevium\|Mendelevium101Md[258]]]	[[ nobelium \|Nobelium102No[259]]]

He