Helium - Helium simple:Helium Hydrogen - Helium He Ne Full table General Name, Symbol, Number Helium, He, 2 Chemical series Noble gases Group, Period, Block 18 (VIIIA), 1, p Density, Hardness 0.1785 kg/m3, N/A Appearance colorless Atomic Properties Atomic weight 4.002602 amu Atomic radius (calc.) no data (31) pm Covalent radius 32 pm van der Waals radius 140 pm Electron configuration 1s2 e- 's per energy level 2 Oxidation states (Oxide) 0 (unknown) Crystal structure hexagonal Physical Properties State of matter gas Melting point 0.95 K (-458 °F) at 26 atm Boiling point 4.22 K (-452.07 °F) Molar volume 21.0 ×1010-3 m3/mol Heat of vaporization 0.0845 kJ/mol Heat of fusion 5.23 kJ/mol Vapor pressure not applicable Speed of sound 970 m/s at 293.15 K Miscellaneous.
Helium-3 - Helium-3 Helium-3 is a non-radioactive and light isotope of helium. It has two protons but only one neutron in contrast to two neutrons in ordinary helium. Helium-3 is rare on Earth and sought-after for use in fusion. More abundant helium-3 is thought to exist on the Moon (embedded in the upper layer of regolith from solar wind over billions of years) and the gas giants (left over from the original solar nebula) in our solar system. Helium-3 is used in cryogenics to achieve temperatures as low as a few thousandths of a kelvin..
Helium fusion - Helium fusion Helium fusion is a kind of nuclear fusion, the two involved nuclei being helium. If the central temperature of a star exceeds 100 million Kelvin, as may happen in the later phase of red giants and red supergiants, then helium can fuse to form beryllium and then carbon. See also Fusion power Cold fusion.
Helium burning - Helium burning Helium burning, or the fusion of helium, requires very high temperatures, to the point where a state of electron degeneration must exist. Only then can helium fusion occur. The triple-alpha process of the fusion produces carbon and occasionally the carbon will react with the alpha particles to produce oxygen. If helium fusion is left alone for awhile, it will produce nothing but carbon and oxygen. This process is much faster, especially compared to hydrogen fusion. KMA of carbon and oxygen requires extremely high temperatures, so fusion of those two elements has yet to be deeply studied..
Helium-neon laser - Helium-neon laser A helium-neon laser, usually called a HeNe laser, is a small gas laser of a type often used in laboratory demonstrations of optics. Its usual operation wavelength is 632.8 nm, in the red portion of the visible spectrum. Schematic diagram of a helium-neon laser The gain medium of the laser, as suggested by its name, is a mixture of helium and neon gases, approximately in the ratio 5:1, contained at low pressure (typically ~300 Pa) in a glass envelope. The energy or pump source of the laser is provided by an electrical discharge of around 1000 V through an anode and cathode at each end of the glass tube. The cavity of the laser typically consists of a plane, high-reflecting mirror at one end.
Primordial helium abundance - Primordial helium abundance The primordial helium abundance refers to the amount of helium in the universe produced shortly after the big bang. Observationally, it comes from the observation that all stars, even very old ones, have a substantial amount of helium, and that this helium is much more than can be explained through stellar production. The amount of primordial helium produced by big bang models varies based on the assumptions, but is consistently above 20%..
Vega - stars in the Sun's neighbourhood. Vega is a vertex of the Summer Triangle. Its spectral class is A0V (Sirius, an A1V, is slightly less powerful) and it's firmly in the main sequence, fusing hydrogen to helium in its core. Since more powerful stars use their fusion fuel more quickly than smaller ones, Vega's life time is only one billion years, a tenth of our Sun's. Vega is two and a half times more massive than our Sun and burns at fifty times the power. Vega has a disk of dust and gas around it, discovered by the IRAS satellite in the mid 1980s. This either signifies planets or planets that may soon form. The protoplanetary disk is, as can be guessed from its name, believed to be a precursor to the.
Venus (planet) - Water vapor Carbon monoxide Argon Helium Neon Carbonyl sulfide Hydrogen chloride Hydrogen fluoride trace Venus is the second planet from the Sun, named after the Roman goddess Venus. It is a terrestrial planet, very similar in size and bulk composition to Earth; it is sometimes called Earth's "sister planet" as a result of this similarity. Sometimes (inaccurately) referred to as the "morning star" or the "evening star", it is by far the brightest "star" in the sky. Because Venus is closer to the Sun than Earth is, it is always in roughly the same direction as the Sun, so on Earth it can only be seen just before sunrise or just after sunset. Physical characteristics Atmosphere Venus has an atmosphere consisting mainly of carbon dioxide and a small amount of nitrogen,.
Vega program - meter, a gas-phase chromatograph, a X-ray spectrometer, a mass spectrometer and a surface sampling device. The Vega 1 lander's surface experiments were inadvertently activated at 20 km from the surface by an especially hard wind jolt and so failed to provide results. The balloon aerobot was a constant-pressure 3.4 metre diameter balloon with instruments, weighing 25 kg in total. It was deployed at 54 km from the surface in the most active layer of the Venuian cloud system. The 5 kg instrument pack had sixty hour batteries and measured temperature, pressure, wind speed and aerosol density. The Vega 1 balloon managed to transmit data for only 56 minutes, but the Vega 2 balloon was much more successful, transmitting data for 46.5 hours. The Vega aerobots The balloons were spherical superpressure types.
James Chadwick - also studied the transmutation of elements by bombarding them with alpha particles and investigated the nature of the atomic nucleus. In 1932 Chadwick made a fundamental discovery in the domain of nuclear science: he discovered the particle in the nucleus of an atom that became known as the neutron because it has no electric charge. In contrast with the helium nuclei (alpha particles) which are charged, and therefore repelled by the considerable electrical forces present in the nuclei of heavy atoms, this new tool in atomic disintegration need not overcome any electric barrier and is capable of penetrating and splitting the nuclei of even the heaviest elements. Chadwick in this way prepared the way towards the fission of uranium 235 and towards the creation of the atomic bomb. For this epoch-making.
Jovian planet - planets were all similar to Jupiter; but, has become less popular after notable differences were found between these planets; mainly, Jupiter and Saturn are primarily composed of hydrogen and helium; while, Uranus and Neptune have less hydrogen/helium, and more water. With the discovery of massive extrasolar planets, the term has seen some renewed usage in describing planets of comparable mass to Jupiter. See also Terrestrial planet.
John Cockcroft - Ernest Rutherford. In 1929 he was elected a Fellow of St. John's College. In 1928 he began to work on the acceleration of protons with Ernest Walton. In 1932 they bombarded Lithium with high energy protons, and succeeded in transmuting it into Helium and other elements. This was the first occasion on which an atomic nucleus of one element had been successfully changed to a different nucleus by artificial means. This feat was popularly, if not strictly accurately, known as splitting the atom. At the outbreak of the Second World War he took up the post of Assistant Director of Scientific Research in the Ministry of Supply, working on radar. In 1944 he took charge of the Canadian Atomic Energy project and became Director of the Montreal and Chalk River Laboratories..
July 2 - Garfield, who eventually dies from infection on September 19, 1881. 1937 - Amelia Earhart and navigator Fred Noonan disappeared over the Pacific Ocean while attempting to make the first round-the-world flight at the equator 1950 - Henri Queuille becomes Prime Minister of France 1973 - James R. Schlesinger was sworn in as the 12th United States Secretary of Defense. 1976 - North and South Vietnam united to form the Socialist Republic of Vietnam. 1982 - Larry Walters uses 45 helium balloons and a lawnchair to propel himself to 16,000 feet. 1992 - Canadian Government closes Cdn$700m northern cod fishery for two years, to conserve stocks. Births 419 - Valentinian III, Roman Emperor (†455) 1644 - Abraham a Santa Clara, court vicar (†1709) 1714 - Christoph Willibald Gluck, composer (†.
Jupiter (planet) - 70 kPa Hydrogen >81% Helium >17% Methane 0.1% Water vapor 0.1% Ammonia 0.02% Ethane 0.0002% Phosphine 0.0001% Hydrogen sulfide <0.0001% Jupiter is the fifth planet from the Sun and, by far, the largest within our solar system; some have described the solar system as consisting of the Sun, Jupiter, and assorted debris. It and the other gas giants Saturn, Uranus, and Neptune are sometimes referred to as "Jovian planets." Table of contents showTocToggle("show","hide") 1 Overview 2 Physical characteristics 2.1 Planetary Composition 2.2 Atmosphere 2.3 Planetary Rings 2.4 Magnetosphere 3 The exploration of Jupiter 4 Jupiter's Moons 5 Cometary impact 6 Jupiter in fiction Overview Jupiter is 2.5 times more massive than all the other planets combined, so massive that its barycenter with the Sun actually lies above the Sun's surface (1.068.
Interstellar medium - tenuous, with typical densities ranging from a few tens to a few hundredths of a particle per cubic centimeter. Generally the gas is roughly 90% hydrogen and 10% helium, with additional elements ("metals", in astronomical parlance) present in trace amounts. The interstellar medium is usually divided into three phases, depending on the temperature of the gas: hot (millions of kelvin), warm (thousands of kelvin), and cold (tens of kelvin). This "three-phase" model of the ISM was initially developed by McKee and Ostriker in a 1977 paper, which has formed the basis for further study over the past quarter-century. The relative proportions of the phases is still a matter of considerable contention in scientific circles. Features prominent in the study of the interstellar medium include molecular clouds, interstellar clouds, supernova remnants, planetary.
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Inert gas - and is usually a member of the noble gas family. Examples include: helium, neon, argon, xenon, krypton, and radon..
Internal energy - of atoms within molecules. For systems consisting of molecules, the internal energy is partitioned among all of these types of motion. In systems consisting of single atoms, such as Helium gas, the internal energy consists only of the kinetic energy of the individual atoms. Internal energy is a fundamental property of thermodynamics. In equations, it is designated by the letter U..
Ion pump - by collision with electrons. Sputtering of titanium by ion bombardment. Titanium gettering of active gases. Pumping of heavy noble gases by ion burial. Diffusion of hydrogen and helium into titanium. Dissociation of complex molecules into simple ones for pumping ease, e.g., CH4 breaks down into C and 2H2. Hydrogen is pumped separately. Carbon is no longer part of the residual gas and resides in solid form. Burial is the basic means of pumping heavy noble gases. Argon ions neutralized via glancing collisions with a sputter cathode impact the pump wall and are coated with sputtered titanium. Triode pumps are specially designed to maximize the kind of collisions that produce energetic neutrals. Argon is permanently pumped on the wall behind the cathode in these pumps. The wall area receives titanium for inert.
IRAS - them, possibily the early stage of a planetary system formation. IRAS life, like most of infrared satellites, was limited by its cooling system: to effectively work in the infrared domain, a satellite must be cooled to impressively low temperatures. In IRAS' case, 720 liters of superfluid helium kept the satellite at a temperature of 1.6 Kelvin (about -272 °C). The fluid keeps the satellite cool by evaporation. When the fluid is totally evaporated, the satellite temperature starts to rise and observations must cease..
