It has likely exhausted its hydrogen and has begun fusing helium into oxygen and carbon in its core.

The first element produced was hydrogen, along with traces of helium and lithium.

Light elements, primarily hydrogen and helium, were created in the Big Bang.

By 1908, James Dewar and H. Kamerlingh Onnes were successfully able to liquify hydrogen and then newly-discovered helium, respectively.

The chemical elements are thought to have been produced by various cosmic processes, including hydrogen, helium ( and smaller amounts of lithium, beryllium and boron ) created during the Big Bang and cosmic-ray spallation.

The lightest of the chemical elements are hydrogen and helium, both created by Big Bang nucleosynthesis during the first 20 minutes of the universe in a ratio of around 3: 1 by mass ( approximately 12: 1 by number of atoms ).

Almost all other elements found in nature, including some further hydrogen and helium created since then, were made by various natural or ( at times ) artificial methods of nucleosynthesis.

Most of the hydrogen and helium in the universe was produced primordially in the first few minutes of the Big Bang.

Nearby galaxies that have evolved along similar lines have a corresponding enrichment of elements heavier than hydrogen and helium.

Very abundant hydrogen and helium are products of the Big Bang, but the next three elements are rare since they had little time to form in the Big Bang and are not made in stars ( they are, however, produced in small quantities by breakup of heavier elements in interstellar dust, as a result of impact by cosmic rays ).

The abundance of elements in Earth's crust differs from those in the universe ( and also the Sun and heavy planets like Jupiter ) mainly in selective loss of the very lightest elements ( hydrogen and helium ) and also volatile neon, carbon, nitrogen and sulfur, as a result of solar heating in the early formation of the solar system.

The 20 % range in relative mass among naturally occurring calcium isotopes is greater than for any element except hydrogen and helium.

The CNO cycle ( for carbon – nitrogen – oxygen ) is one of two sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton – proton chain.

Because of the long timescales involved, the cold CNO cycles convert hydrogen to helium slowly, allowing them to power stars in quiescent equilibrium for many years.

The first proposed catalytic cycle for the conversion of hydrogen into helium was at first simply called the carbon – nitrogen cycle ( CN cycle ), also honorarily referred to as the Bethe – Weizsäcker cycle, because it does not involve a stable isotope of oxygen.

This is a logical dividing line, since the normal boiling points of the so-called permanent gases ( such as helium, hydrogen, neon, nitrogen, oxygen, and normal air ) lie below − 180 ° C while the Freon refrigerants, hydrogen sulfide, and other common refrigerants have boiling points above − 180 ° C.

Ordinary stars are composed mainly of the light elements hydrogen and helium.

Neutrons and other particles heavier than protons, as well as helium and other atoms with more than one proton, are so rare that their total mass in the visible universe is much less than the total mass of protons in hydrogen atoms.

At this point the universe was almost exclusively composed of hydrogen, helium, and dark matter.

Soon after the first proto-galaxies formed, the hydrogen and helium gas within them began to condense and make the first stars.

* Halo stars are typically much older and have much lower metallicities ( that is to say, they are almost exclusively composed of hydrogen and helium ) than disk stars.

About 300, 000 years after this event, atoms of hydrogen and helium began to form, in an event called recombination.

These were composed almost entirely of hydrogen and helium, and may have been massive.

This matter is mostly hydrogen and helium.

)</ ref >< ref name = Lackner2012 > Such carbon neutral and negative fuels can be produced by the electrolysis of water to make hydrogen used in the Sabatier reaction to produce methane which may then be stored to be burned later in power plants as synthetic natural gas, transported by pipeline, truck, or tanker ship, or be used in gas to liquids processes such as the Fischer – Tropsch process to make traditional transportation or heating fuels .< ref name = Pearson2012 > ( Review.

Relative to their mass, traditional hypergolic propellants are less energetic than some cryogenic propellant combinations, such as liquid hydrogen / liquid oxygen or liquid methane / liquid oxygen.

The second important aspect of SA is the key role of weak interactions ( e. g. Van der Waals, capillary,, hydrogen bonds ) with respect to more " traditional " covalent, ionic or metallic bonds.

However, as hydrogen is much less dense than " traditional " fuels then in use, essentially kerosene, the upper stage would have to be fairly large in order to hold enough fuel.

)</ ref >< ref name = Lackner2012 > Such carbon neutral and negative fuels can be produced by the electrolysis of water to make hydrogen used in the Sabatier reaction to produce methane which may then be stored to be burned later in power plants as synthetic natural gas, transported by pipeline, truck, or tanker ship, or be used in gas to liquids processes such as the Fischer – Tropsch process to make traditional transportation or heating fuels .< ref name = Pearson2012 > ( Review.

Comparing modern dynamic flash combustion coupled with gas chromatography with traditional combustion analysis will show that the former is both faster and allows for simultaneous determination of multiple elements while traditional determination allowed only for the determination of carbon and hydrogen.

At 0, 08 $/ kWh, that's $ 4. 00 / kg, which is with traditional methods 3 to 10 times the price of hydrogen from steam reformation of natural gas.

The hydrogen atoms sitting between the oxygen atoms have some degree of freedom as long as each oxygen atom has two hydrogen atoms that are ' nearby ', thus forming the traditional H < sub > 2 </ sub > O water molecule.

in interstellar gas, concentrations as low as Af molecules per Af may be sufficient, as compared to the Af hydrogen atom's Af required for detection of the 21-cm line.

The positively charged hydrogen ions ( protons ) capture electrons from the copper, forming bubbles of hydrogen gas, H < sub > 2 </ sub >.

Also, the power of the cell diminishes over time because the hydrogen gas is not released, accumulating instead on the surface of the zinc electrode and forming a barrier between the metal and the electrolyte solution.

Reactions with water and alcohols are also very exothermic and release hydrogen gas:

* The Lyman alpha forest, which allows cosmologists to measure the distribution of neutral atomic hydrogen gas in the early universe, by measuring the absorption of light from distant quasars by the gas.

Progressing through the states, hydrochloric acid can be oxidized using manganese dioxide, or hydrogen chloride gas oxidized catalytically by air to form elemental chlorine gas.

Calcium metal reacts with water, evolving hydrogen gas at a rate rapid enough to be noticeable, but not fast enough at room temperature to generate much heat.

They were formed by H < sub > 2 </ sub > S ( hydrogen sulfide ) gas rising from below, where reservoirs of oil give off sulfurous fumes.

In this way the particularly strong triple bond in nitrogen is weakened and the hydrogen and nitrogen atoms combine faster than would be the case in the gas phase, so the rate of reaction increases.

One of the most obvious applications of catalysis is the hydrogenation ( reaction with hydrogen gas ) of fats using nickel catalyst to produce margarine.

For example, simple hydrogen gas combined with simple oxygen gas can produce a more complex substance, such as water.

Common results of reduction at the cathode are hydrogen gas or pure metal from metal ions.

It can react with water to produce flammable hydrogen gas.

The term standard in SHE requires a supply of hydrogen gas bubbled through the electrolyte at a pressure of 1 atm and an acidic electrolyte with H < sup >+</ sup > activity equal to 1 ( usually assumed to be

Some engines convert heat from noncombustive processes into mechanical work, for example a nuclear power plant uses the heat from the nuclear reaction to produce steam and drive a steam engine, or a gas turbine in a rocket engine may be driven by decomposing hydrogen peroxide.

* Catalase test on nutrient agar tests for the production of catalase enzyme, which splits hydrogen peroxide and releases oxygen gas.

The chemical reactions in the cell may involve the electrolyte, the electrodes or an external substance ( as in fuel cells which may use hydrogen gas as a reactant ).

This contains the alkene functional group and can now dimerize with another isobutene to give iso-octene, which is then catalytically hydrogenated to iso-octane using pressured hydrogen gas.

However, gas chromatography testing in 1984 revealed that sulfur-containing compounds, such as methanethiol, hydrogen sulfide ( rotten egg smell ) and dimethyl sulfide, were also < ref >

If water is evaporated too quickly, the membrane dries, resistance across it increases, and eventually it will crack, creating a gas " short circuit " where hydrogen and oxygen combine directly, generating heat that will damage the fuel cell.

The oxygen ions then travel through the electrolyte to react with hydrogen gas at the anode.