Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.[a] Its boiling and melting point are the lowest among all the elements. It is the second lightest and second most abundant element in the observable universe (hydrogen is the lightest and most abundant). It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and in Jupiter, 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. Most helium in the universe is helium-4, the vast majority of which was formed during the Big Bang. Large amounts of new helium are created by nuclear fusion of hydrogen in stars. Helium was first detected as an unknown, yellow spectral line signature in sunlight during a solar eclipse in 1868 by Georges Rayet,[11] Captain C. T. Haig,[12] Norman R. Pogson,[13] and Lieutenant John Herschel,[14] and was subsequently confirmed by French astronomer Jules Janssen.[15] Janssen is often jointly credited with detecting the element, along with Norman Lockyer. Janssen recorded the helium spectral line during the solar eclipse of 1868, while Lockyer observed it from Britain. Lockyer was the first to propose that the line was due to a new element, which he named. The formal discovery of the element was made in 1895 by chemists Sir William Ramsay, Per Teodor Cleve, and Nils Abraham Langlet, who found helium emanating from the uranium ore, cleveite, which is now not regarded as a separate mineral species, but as a variety of uraninite.[16][17] In 1903, large reserves of helium were found in natural gas fields in parts of the United States, by far the largest supplier of the gas today.
Elven gymyk yw heliom, niver 2 y'n Vosen Beriodek. Y furvell yw He. An hanow a dheu dhyworth an ger Greka helios, ow styrya howl. Diskudhys veu heliom y'n howl kyns veu kevys war an norvys. Heliom yw onan a'n elvennow veu gwrys y'n Bomm Bras, warbarth gans hidrojen ha lithiom. Hi yw an elven nessa moyha pals y'n Ollvys (23%), wosa hidrojen (76%). Ster a askorr heliom dre gesteudhans nuklesennow hidrojen. Nyns eus rann dhe heliom y'n korf denel. Usys yw heliom linyek gans tempredh a -269°C dhe yeynhe tennveyn, res dhe askorra skeusennow MRI. Pan hwer difyk howl, lettys yw an rann vrassa dhe wolow an Howl. Hemm a wra gasa dielvennans spektrum an korona, dell dybi Pierre J.C.Jansen (1824-1907). Ev eth dhe Eynda rag studhya difyk howl leun yn 1868. Digomol veu an ebron war an 18ves mis Est, hag ev a allas musura an spektrum. Pan welas ev linen y'n spektrum gans tonnhyw a 587.49nm, ev a wodhva bos elven ankoth ena. War an 20ves mis Hedra y'n keth bledhen, Norman Lockyer (1836-1920) hag Edward Frankland (1825-1899) a welas an keth linen dre ebron Loundres leun a vog. Lockyer a wrug batha'n hanow heliom. Kevys yw heliom dhyworth gass naturel (ow komprehendya bys dhe 7% anodho). Yma an kreunyow moyha yn Katar hag Iran. Askorrys yw dres 100 milvil meter kubek an vledhen (90% anedha y'n Statys Unys). Usys yw rag pelyow ayr, gans sedhoryon dhownvor (dhe lettya re nitrojen y'n goos), ha rag daffar tempredh-isel, kepar ha tennveyn ughkendegi. https://kw.wikipedia.org/wiki/Restren:HeNe_Laser_Build.webm1:01 Heliom Poos atomek heliom yw 4.003. Y boynt teudhi yw -272°C ha'y boynt bryjyon yw -269°C. Y dhosedh yw 0.18g an liter. Gass diliw anvlasus yw. Ny wra dasoberi yn kymyk. Yn-dann tempredh a -271°C (2°K) heliom a wra mos ha bos lin heb glusekter.langbot langbot