Hydrogen

Hydrogen/oxygen mixtures are explosive across a wide range of proportions. Its autoignition temperature, the temperature at which it ignites spontaneously in air, is 560 °C (1,040 °F).

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H.

Hydrogen burns clean and nearly everyone agrees that running vehicles with hydrogen fuel cells instead of oil would be a great step forward for the environment. So what prevents hydrogen from replacing oil as the fuel of choice for most vehicles?

Is hydrogen necessary for the creation of stars. Can stars be born out of the fusion of heavier elements? What happens when molecular hydrogen in the Universe is exhausted or get to be very rare ? The Answer ...

Definition: hydrogen: The lightest and most abundant element. A hydrogen atom consists of one proton and one electron. Hydrogen composes about 75 percent of the Sun but only a tiny fraction of the Earth.

Hydrogen is the most abundant of the chemical elements, constituting roughly 75% of the universe's elemental mass. Stars in the main sequence are mainly composed of hydrogen in its plasma state.

hydrogen a gas that has no color or smell and burns very easily. It is a chemical element and the lightest of all substances ...

Neutral hydrogen atoms emit electromagnetic radiation at a wavelength of 21.1cm as a result of the atom's single electron changing from having spin parallel to that of the nucleus, to having spin antiparallel to that of the nucleus.

Hydrogen and helium and some lithium, boron, and beryllium were created when the universe was created. All of the rest of the elements of the universe were produced by the stars in nuclear fusion reactions.

hydrogen shell burning Fusion of hydrogen in a shell that is driven by contraction and heating of the helium core.

Hydrogen cloud--A huge section of hydrogen. Dust tail--The most visible part of the comet made of dust particles from the nucleus. Dust tails are very long and smoke-like.

Hydrogen fusing stars which fall on a single line in the . The lifetime of a main sequence star of mass M and luminosity L is given by From the main sequence where is the mass of the and its luminosity, it follows that ...

Hydrogen and Helium Anatomy of Galaxies Novae and Supernovae Birth of Stars Telescopes and Modern Observatories ...

Hydrogen fusion begins : star is "born" evolutionary tracks on H-R diagram Zero Age Main Sequence (ZAMS) location on MS mass dependent (O high, M low) formation time mass dependent (O short, M long) ...

Hydrogen is ionized by absorption of Lyman continuum photons (l « 912 Å, energy above 13.6 eV). The line radiation we detect arises from recombination of the electrons so released with another proton, and a cascade toward the ground state.

Hydrogen-atmosphere variable white dwarf (Spectral Class DAV4.3). How Far Away: 50 light years.

Hydrogen will only absorb light if the star is at the right temperature. If the star is too hot or too cool, the hydrogen will not absorb this light.

Hydrogen The most common gas in the universe. Each atom of hydrogen contains one proton. A.. B.. C.. D.. E.. F.. G.. H.. I.. J.. K.. L.. M.. N.. O.. P.. Q.. R.. S.. T.. U.. V.. W.. X.. Y.. Z..

Hydrogenated Amorphous Carbon Hades An unofficial name for Jupiter IX, the outermost satellite of Jupiter (P = 758 days retrograde, i = 156°, e = 0.28). Discovered by Nicholson in 1914.

Hydrogen (H) lines strongest for A0 stars, decreasing for other A's. Sirius, Vega F ...

hydrogen -- no longer used because of the high flammability. See Hindenburg disaster helium ...

hydrogen - (n.) simplest atom, consisting only of one proton and one electron; the most abundant element in the Universe. hypotheses - (n.) ...

Hydrogen An element consisting of one electron and one proton. Hydrogen is the lightest of the elements and is the building block of the universe. Stars form from massive clouds of hydrogen gas.

Hydrogen-deficient C-type stars. [JJ95] Reaction Rate The rate at which a chemical or nuclear reaction proceeds.

HYDROGEN Hydrogen is the element with the atomic number 1. It is the lightest element and the most abundant in the universe. Its nucleus is a single proton which is orbited by one electron.

Hydrogen: An element with atomic number 1; symbol: H. It is the most abundant element in the solar system, making up 90 percent of the Sun. Hydrogen, carbon, nitrogen, and oxygen are essential for life.

hydrogen The lightest and most abundant element. Average stars like the Sun are composed mostly of hydrogen, which is being converted into helium. I ...

hydrogen burning -- nuclear fusion of hydrogen into helium. It is not "burning" like ordinary fire, but is instead the transformation of one kind of atom into another accompanied by the release of energy.

Hydrogen bomb A type of extremely large nuclear bomb, releasing fusion energy of heavy hydrogen (or in later versions, lithium) as well as fission energy of plutonium and uranium.

Hydrogen and calcium emissions reveal huge regions of cool, dense gas suspended above the photosphere by powerful magnetic fields. The cool gas looks dark against the brightness of the Sun beneath it.

Hydrogen is the most abundant element in the universe so we should be able to detect lots of it. However, most of it will be at very low temperatures, too low to be ionized or to have many atoms with electrons up in the higher energy orbits.

A Hydrogen-alpha filter will give you a new perspective on our daytime star.

A: Hydrogen. The is made up of about 75% hydrogen and 25% helium. About 0.1% is metals (made from hydrogen via nuclear fusion).

83% hydrogen, 15% helium, 2% methane (at depth) Rings Uranus has a system of narrow, faint rings. Ring particles are dark, and could consist of rocky or carbonaceous material.

DSN HYDROGEN MASER Down in the basement of each DSN complex, there looms a hydrogen-maser-based frequency standard in an environmentally controlled room, sustained by an uninterruptable power supply.

Even hydrogen, the bulk of the substance of Jupiter other than some helium and traces of various ices, becomes liquid in the interior of the gas planet when the pressure exerted by the weight of the upper layers exceeds four million bars.

Both hydrogen and helium are clear gasses, so why is the king of the planets tan and brown rather than having a clear atmosphere that would allow us to see down to its "surface' of liquid metallic hydrogen?

1H == hydrogen atom with only a proton in its nucleus 2H == deuterium, hydrogen atom with a proton and neutron in its nucleus 3H == tritium, hydrogen atom with a proton and 2 neutrons in its nucleus ...

21-cm Hydrogen Line: Radio emission of a very specific radio frequency of 1420 MHz by a neutral hydrogen atom when its single electron flips, emitting a single photon of energy with a wavelength of 21 centimeters. W Top of page ...

Enough hydrogen is left in the sun's core to last another 4.5 billion years.

Metallic Hydrogen - A form of hydrogen in which the atoms have been forced into a lattice structure typical of metals.

[9.6] THE HYDROGEN ECONOMY? [9.7] FOOTNOTE: OTHER INDUSTRIAL CHEMICALS [10.0] Traditional Materials ...

A form of hydrogen under high pressure that is a good electrical conductor. Lobate Scarp A curved cliff such as those found on Mercury.

As a star's hydrogen is converted into helium, its chemical composition becomes inhomogeneous: helium-rich in the core, where the nuclear reactions occur, and more nearly pure hydrogen in the surrounding envelope.

They 'burn' hydrogen into helium in their centres during the main-sequence phase but eventually there is no hydrogen left in the centre to provide the necessary pressure to balance the inward pull of gravity.

When the core hydrogen runs out, main sequence stars balloon outward to become (depending on their masses) giants or supergiants. The lower a star's birth mass, the longer it will live.

If you have a hydrogen discharge tube, have students measure the wavelengths of the Balmer lines for themselves. If not, tell them to use the table provided on the site. In Exercise 14, point out that the lines are marked on the spectrum.

Running out of Hydrogen In part 1, a star was described as sort of a nuclear furnace which is held together by gravity and powered by hydrogen being fused into helium and producing heat and light.

Initially, the hydrogen-fusing shell of an AGB star is responsible for most of the star's energy output.

As the Sun burns hydrogen at its core, it releases vast amounts of atomic particles, or pieces of atoms into outer space. These atomic particles, along with the Sun's radiation create a sort of wind, known as the solar wind.

The large atomic hydrogen halo detected up to 107 kilometres from the nucleus is simply a large coma visible in ultraviolet (Lyman-alpha line).

A special form of hydrogen (an isotope called "heavy hydrogen") that has a neutron as well as a proton in its nucleus. Diameter ...

Eventually, all the hydrogen, helium, and those products that could be used to generate energy in the core of the star, were exhausted, and the nuclear furnace was extinguished.

aldehydes (NASA Thesaurus) Carbonyl groups to which a hydrogen atom is attached; the first stage of an alcohol; - CHO.

plages Clouds of calcium or hydrogen vapor that show up as bright patches on the surface of the photosphere of the sun. Planck constant (symbol h) A constant equal to 6.6256 X 10E-27 erg second.

This ABSORPTION LINE of neutral hydrogen falls in the red part of the visible spectrum and is convenient for solar observations. The H-alpha line is universally used for patrol observations of solar flares. H-component of the Geomagnetic Field.

into two divisions, called helium and hydrogen stars respectively. The former are often called " Orion " stars, as all the brighter stars in that constellation with the exception of Betelgeux belong to the helium type.

A calculation of thermal evolution shows that Saturn could have originated with the gravitational collapse of gaseous hydrogen and helium from the original solar nebula onto a massive ice-rich core of perhaps 10 to 20 Earth masses.

In the nebula is hydrogen gas which is pulled together by gravity and starts to spin faster. Over millions of years, more hydrogen gas is pulled into the spinning cloud.

So far, the Sun has fused about half of the hydrogen originally in its core into helium to create energy.

See also: Light, Sun, Solar, Mass, Earth