helium

Definition von helium im Englisch Englisch wörterbuch: A form or sample of the element; A colorless and inert gas, and the second lightest chemical element (symbol He) with an atomic number of 2 and atomic weight of 4.002602; second lightest gas; does not cause problems of narcosis seen with nitrogen, and is therefore used for very deep diving; A gaseous element found in the atmospheres of the sun and earth and in some rare minerals; It is a decomposition product of the radium emanation; A colorless, odorless, tasteless, inert gaseous element Jovian planets are rich in hydrogen and helium whereas the terrestrial planets are not; A colorless, nontoxic, noncombustible gas Uses include welding, leak detection, chromatography, geological dating, diving Hazard: Simple asphyxiant; 98 compared with hydrogen, and is more difficult to liquefy than the latter; Second lightest gas; dies not cause problems of narcosis to the same extent as seen with nitrogen, and is therefore used for very deep diving; Helium is a very light gas that is colourless and has no smell. a gas that is lighter than air and is used to make balloons float. It is a chemical element : symbol He (helios ; because it was discovered in the sun's spectrum). Chemical element, chemical symbol He, atomic number; wt; The empire of the grandfather of Dejah Thoris; One of the lightest elements, second only to hydrogen Helium is one of the harmless by-products of nuclear fusion It is also used in balloons and will make your voice squeaky if you inhale it Don't inhale too much, though Your body needs a little oxygen, too - WebElements: Helium; the second lightest and second most abundant element in the Universe The helium atom consists of a nucleus of two protons and two neutrons surrounded by two electrons Helium was first discovered in our Sun Roughly 5 percent of our Sun is helium; a very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy; occurs in economically extractable amounts in certain natural gases (as those found in Texas and Kansas); An inert gas A colorless, monatomic element which is found to occur in dry air to the extent of only 0 000524 percent by volume Helium is very light, having a molecular weight of only 4 003 and specific gravity referred to air of 0 138 Because helium is non-inflammable and has a lifting power 92 percent of that of hydrogen, it is widely used as the inflation gas for meteorological balloons; Helium has a density of 1; {i} inert gaseous element; a chemical element usually in gaseous state; An inert gas that is lighter than air (either Nike AIR or normal breathing air) Predominately sourced from natural gas wells in Texas Converse introduced a basketball shoe with helium in November 1999, followed by a helium-cushioned skate shoe in 2000; An inert, monoatomic, gaseous element occurring in the atmosphere of the sun and stars, and in small quantities in the earth's atmosphere, in several minerals and in certain mineral waters; Chemically, it belongs to the argon group and cannot be made to form compounds; Helium was first detected spectroscopically in the sun by Lockyer in 1868; it was first prepared by Ramsay in 1895; A noble gas, it is colourless, odourless, tasteless, completely unreactive, and nontoxic. First found by spectroscopy of the Sun's atmosphere in 1868, it is the second most abundant and second-lightest element in the universe (after hydrogen). Helium makes up a tiny proportion of the atmosphere but as much as 7% of natural gas. It is the product of radioactive decay (see radioactivity) and is used in helium dating. It is used as an inert gas in welding, rocket propulsion, balloon flight, hyperbaric chambers, deep-sea diving (see nitrogen narcosis), gas chromatography, luminous signs, and cryogenics. Liquid helium, which exists only below -452 °F (-268.9 °C, about 4° C above absolute zero), is a "quantum fluid" (see fluid mechanics; quantum mechanics), with unique properties, including superfluidity, superconductivity, and near-zero viscosity; Symbol, He; at; Lightest rare gas atom whose nucleus consists of two protons and two neutrons The lowest energy shell is filled up with two electrons This explains the chemical inertness of the helium atom; The second lightest and second most abundant element The typical helium atom consists of a nucleus of two protons and two neutrons surrounded by two electrons Helium was first discovered in our Sun Roughly 25 percent of our Sun is helium; a gas; he
helium burning: the nucleosynthesis process, in stars where temperatures exceed 108K, in which helium is converted to carbon and subsequently to oxygen, neon and magnesium
helium dating: a method of determining the age of rock that depends on the production of helium during the decay of various radioactive isotopes of uranium and thorium
helium flash: The sudden beginning of the burning of helium in the core of stars of intermediate mass or on the surface of an accreting white dwarf
helium fusion: Nuclear fusion involving helium nuclei
helium speech: the effect on the timbre of speech after inhaling helium, due to the difference in the speed of sound in that gas (note - there is no difference in the pitch of the sound produced)
helium star: A star which has lost most or all of its hydrogen, leaving just a core of helium
helium stars: plural form of helium star
helium variable: A star in which the strength of the helium absorption lines vary periodically; at times appearing to be a helium star
helium variables: plural form of helium variable
helium-3: The rare isotope of helium, 32He, that has a single neutron
helium-4: The normal isotope of helium, 42He, that has two neutrons
helium I: Liquid helium existing as a normal fluid between the superfluid transition point of approximately 2.2°K at 1 atmosphere pressure and its boiling point of 4.2°K
helium II: Liquid helium existing as a superfluid below the transition point of approximately 2.2°K at 1 atmosphere and having extremely low viscosity and extremely high thermal conductivity
helium balloon: balloon that is filled with helium
helium dating: Method of dating that depends on the production of helium during the decay of radioactive isotopes of uranium and thorium. Because of this decay, the helium content of any mineral or rock capable of retaining helium will increase during the lifetime of that mineral or rock, and the ratio of helium to its radioactive progenitors then becomes a measure of geologic time. Fossils may also be dated by helium dating. The relatively large amount of helium produced in rocks may make it possible to extend helium dating to rocks and minerals as young as a few tens of thousands of years old
helium group: the series of inert gases
liquid helium: the liquified form of helium that does not solidify even at absolute zero; it shows unusual properties, such as superfluidity, due to quantum effects