Hydrogen Facts For Sleep

Welcome to the I Can't Sleep podcast,

Where I help you learn a little and sleep a lot.

The purpose of this podcast is to educate you in part,

But with the hopes that over time,

My soothing voice will help you to drift off to sleep.

Now let's get on to tonight's episode,

Which is about hydrogen.

Hydrogen is a chemical element.

It has symbol H and atomic number one.

It is the lightest and most abundant chemical element in the universe,

Constituting about 75% of all normal matter.

Stars,

Including the sun,

Mainly consist of hydrogen in a plasma state.

While on earth,

Hydrogen is found in water and organic compounds,

As the gas H2 dihydrogen,

And in other molecular forms.

The most common isotope of hydrogen consists of one proton,

One electron,

And no neutrons.

Under standard conditions,

Hydrogen is a gas of diatomic molecules with a formula H2 called dihydrogen,

Or sometimes hydrogen gas,

Molecular hydrogen,

Or simply hydrogen.

Dihydrogen is colorless,

Odorless,

Non-toxic,

And highly combustible.

Hydrogen gas was first produced artificially in the 17th century by the reaction of acids with metals.

Henry Cavendish in 1766 to 1781 identified hydrogen gas as a distinct substance and discovered its property of producing water when burned.

Hence,

Its name means water former in Greek.

Understanding the colors of light absorbed and emitted by hydrogen was a crucial part of developing quantum mechanics.

Hydrogen,

Typically non-metallic,

Except under extreme pressure,

Readily forms covalent bonds with most non-metals.

Contributing to the formation of compounds like water and various organic substances.

Its role is crucial in acid-base reactions,

Which mainly involve proton exchange among soluble molecules.

In ionic compounds,

Hydrogen can take the form of either a negatively charged anion,

Or it is known as hydride,

Or as a positively charged cation,

H+,

Called a proton.

Although tightly bonded to water molecules,

Protons strongly affects the behavior of aqueous solutions as reflected in the importance of pH.

Hydride,

On the other hand,

Is rarely observed because it tends to deprotonate solvents yielding H2.

In the early universe,

Neutral hydrogen atoms formed about 370,

000 years after the Big Bang as the universe expanded and plasma had cooled enough for electrons to remain bound to protons.

Once stars formed,

Most of the atoms in the intergalactic medium re-ionized.

Nearly all hydrogen production is done by transforming fossil fuels,

Particularly steam reforming of natural gas.

It can also be produced from electricity by electrolysis.

However,

This process is more expensive.

Its main industrial uses include fossil fuel processing and ammonia production for fertilizer.

Emerging uses for hydrogen include the use of fuel cells to generate electricity.

Let's talk about the properties.

Atomic hydrogen,

Electron energy levels.

The ground state energy level of the electron in a hydrogen atom is negative 13.

6 electron volts,

Equivalent to an ultraviolet photon of roughly 91 nanometer wavelength.

The energy levels of hydrogen are referred to by consecutive quantum numbers with N equals one being the ground state.

The hydrogen spectral series corresponds to emission of light due to transitions from higher to lower energy levels.

Each energy level is further split by spin interactions.

Between the electron and proton into four hyperfine levels.

High precision values for the hydrogen atom energy levels are required for definitions of physical constants.

Quantum calculations have identified nine contributions to the energy levels.

The eigenvalue from the Dirac equation is the largest contribution.

Other terms include relativistic recoil,

The self energy and the vacuum polarization terms.

Isotopes.

Hydrogen has three naturally occurring isotopes denoted 1H,

2H and 3H.

Other highly unstable nuclei,

4H to 7H,

Have been synthesized in the laboratory but not observed in nature.

1H is the most common hydrogen isotope with an abundance of greater than 99.

98%.

Because the nucleus of this isotope consists of only a single proton,

It is given the descriptive but rarely used formal name,

Proteome.

It is the only stable isotope with no neutrons.

2H,

The other stable hydrogen isotope,

Is known as deuterium and contains one proton and one neutron in the nucleus.

Nearly all deuterium nuclei in the universe is thought to have been produced at the time of the Big Bang and has endured since then.

Deuterium is not radioactive and is not a significant toxicity hazard.

Water enriched in molecules that include deuterium instead of normal hydrogen is called heavy water.

Deuterium and its compounds are used as a non-radioactive label in chemical experiments and in solvents for 1H NMR spectroscopy.

Heavy water is used as a neutron moderator and coolant for nuclear reactors.

Deuterium is also a potential fuel for commercial nuclear fusion.

3H is known as tritium and contains one proton and two neutrons in its nucleus.

It is radioactive,

Decaying into helium-3 through beta decay with a half-life of 12.

32 years.

It is radioactive enough to be used in luminous paint to enhance the visibility of data displays such as for painting the hands and dial markers of watches.

The watch glass prevents the small amount of radiation from escaping the case.

Small amounts of tritium are produced naturally by cosmic rays striking atmospheric gases.

Tritium has also been released in nuclear weapons tests.

It is used in nuclear fusion as a tracer in isotope geochemistry and in specialized self-powered lightning devices.

Tritium has also been used in chemical and biological labeling experiments as a radiolabel.

Unique among the elements,

Distinct names are assigned to its isotopes in common use.

During the early study of radioactivity,

Heavy radioisotopes were given their own names.

But these are mostly no longer used.

The symbols D and T instead of 2H and 3H are sometimes used for deuterium and tritium.

But the symbol P was already used for phosphorus and thus was not available for protium.

In its nomenclatural guidelines,

The International Union of Pure and Applied Chemistry,

IUPAC,

Allows any of D,

T,

2H and 3H to be used,

Though 2H and 3H are preferred.

Antihydrogen,

H,

Is the antimatter counterpart to hydrogen.

It consists of an antiproton with a positron.

Antihydrogen is the only type of antimatter atom to have been produced as of 2015.

The exotic atom muonium,

Symbol Mu,

Composed of an antimuon and an electron is analogous hydrogen and IUPAC nomenclature incorporates such hypothetical compounds as muonium chloride,

MuCl,

And sodium muonide,

NaMu,

Analogous to hydrogen chloride and sodium chloride respectively.

Dihydrogen,

Under standard conditions,

Hydrogen is a gas of diatomic molecules with the formula H2,

Often called dihydrogen,

But also called molecular hydrogen,

Or simply hydrogen.

Dihydrogen is a colorless,

Odorless,

Flammable gas.

Combustion,

Hydrogen gas is highly flammable,

Reacting with oxygen and air to produce liquid water.

2H2 gas plus O2 gas yields 2H2O liquid.

The amount of heat released per mole of hydrogen is negative 286 kilojoules,

Or 141.

865 megajoules for a kilogram mass.

Hydrogen gas forms explosive mixtures with air in concentrations from four to 74% and with chlorine at five to 95%.

The hydrogen auto-ignition temperature,

The temperature of spontaneous ignition in air,

Is 500 degrees Celsius,

Or 932 degrees Fahrenheit.

In a high-pressure hydrogen leak,

The shock wave from the leak itself can heat air to the auto-ignition temperature,

Leading to flaming and possibly explosion.

Hydrogen flames emit faint blue and ultraviolet light.

Flame detectors are used to detect hydrogen fires as they are nearly invisible to the naked eye in daylight.

Spin isomers.

Molecular H2 exists as two nuclear isomers that differ in the spin states of their nuclei.

In the orthohydrogen form,

The spins of the two nuclei are parallel,

Forming a spin triplet state,

Having a total molecular spin,

S equals one.

In the para-hydrogen form,

The spins are anti-parallel and form a spin singlet state,

Having a spin,

S equals zero.

The equilibrium ratio of ortho to para-hydrogen depends on temperature.

At room temperature or warmer,

Equilibrium hydrogen gas contains about 25% of the para form and 75% of the ortho form.

The ortho form is an excited state,

Having higher energy than the para form by 1.

455 kilojoules per mole.

And it converts to the para form over the course of several minutes when cooled to low temperature.

The thermal properties of these isomers differ because each has distinct rotational quantum states.

The ortho to para ratio in H2 is an important consideration in the liquefaction and storage of liquid hydrogen.

The conversion from ortho to para is exothermic and produces sufficient heat to evaporate most of the liquid,

If not converted first to para-hydrogen during the cooling process.

Catalysts for the ortho para interconversion,

Such as ferric oxide and activated carbon compounds are used during hydrogen cooling to avoid this loss of liquid.

Phases.

Liquid hydrogen can exist at temperatures below hydrogen's critical point of 33 Kelvin.

However,

For it to be in a fully liquid state at atmospheric pressure,

H2 needs to be cooled to 20.

28 Kelvin.

Hydrogen was liquefied by James Dewar in 1898 by using regenerative cooling and his invention,

The vacuum flask.

Liquid hydrogen becomes solid hydrogen at standard pressure below hydrogen's melting point of 14.

01 Kelvin.

Distinct solid phases exist,

Known as phase one through phase five,

Each exhibiting a characteristic molecular arrangement.

Liquid and solid phases can exist in combination of the triple point,

A substance known as slush hydrogen.

Metallic hydrogen,

A phase obtained at extremely high pressures,

In excess of 400 gigapascals,

Is an electrical conductor.

It is believed to exist deep within giant planets like Jupiter.

When ionized,

Hydrogen becomes a plasma.

This is the form in which hydrogen exists within stars.

In 1671,

Irish scientist Robert Boyle discovered and described the reaction between iron fillings and dilute acids,

Which results in the production of hydrogen gas.

Boyle did note that the gas was inflammable,

But hydrogen would play a key role in overturning the phlogiston theory of combustion.

In 1766,

Henry Cavendish was the first to recognize hydrogen gas as a discrete substance by naming the gas from a metal acid reaction,

Inflammable air.

He speculated that inflammable air was in fact identical to the hypothetical substance phlogiston,

And further finding in 1781 that the gas produces water when burned.

He is usually given credit for the discovery of hydrogen as an element.

In 1783,

Antoine Lavoisier identified the element that came to be known as hydrogen when he and Laplace reproduced Cavendish's finding that water is produced when hydrogen is burned.

Lavoisier produced hydrogen for his experiments on mass conservation by treating metallic iron with a stream of H2O through an incandescent iron tube heated in a fire.

Anaerobic oxidation of iron by the protons of water at high temperature can be schematically represented by the set of following reactions.

Iron plus water yields iron 2 oxide and hydrogen gas.

Two iron atoms plus three water molecules produce iron 3 oxide and three hydrogen molecules.

Three iron atoms plus four water molecules yield iron 2,

3 oxide and four hydrogen molecules.

Many metals react similarly with water leading to the production of hydrogen.

In some situations,

This H2 producing process is problematic as is the case of zirconium cladding on nuclear fuel rods.

By 1806,

Hydrogen was used to fill balloons.

Francois Isaac de Rivaz built the first de Rivaz engine,

An internal combustion engine powered by a mixture of hydrogen and oxygen in 1806.

Edward Daniel Clark invented the hydrogen gas blowpipe in 1819.

The Durberiner's lamp and limelight were invented in 1823.

Hydrogen was liquefied for the first time by James Dewar in 1898 by using regenerative cooling and his invention,

The vacuum flask.

He produced solid hydrogen the next year.

One of the first quantum effects to be explicitly noticed but not understood at the time was James Clerk Maxwell's observation that the specific heat capacity of H2 unaccountably departs from that of diatomic gas below room temperature and begins to increasingly resemble that of monatomic gas at cryogenic temperatures.

According to quantum theory,

This behavior arises from the spacing of the quantized rational energy levels which are particularly wide spaced in H2 because of its low mass.

These widely spaced levels inhibit equal partition of heat energy and a rotational motion in hydrogen at low temperatures.

Diatomic gases composed of heavier atoms do not have such widely spaced levels and do not exhibit the same effect.

The existence of the hydride anion was suggested by Gilbert and Lewis in 1916 for group one and two salt-like compounds.

In 1920,

Moore's electrolyzed molten lithium hydride producing a stoichiometric quantity of hydrogen at the anode.

Because of its simple atomic structure consisting only of a proton and an electron,

The hydrogen atom together with the spectrum of light produced from it or absorbed by it has been central to the development of the theory of atomic structure.

The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom in which the electron orbits the proton like how Earth orbits the sun.

However,

The electron and proton are held together by electrostatic attraction.

While planets and celestial objects are held by gravity.

Due to the discretization of angular momentum postulated in early quantum mechanics by Bohr,

The electron in the Bohr model can only occupy certain allowed distances from the proton and therefore only certain allowed energies.

Hydrogen's unique position as the only neutral atom for which the Schrodinger equation can be directly solved has significantly contributed to the understanding of quantum mechanics through the exploration of its energetics.

Furthermore,

Study of the corresponding simplicity of the hydrogen molecule and the corresponding cation H plus two brought understanding of the nature of the chemical bond which followed shortly after the quantum mechanical treatment of the hydrogen atom had been developed in the mid 1920s.

Because H two is only 7% the density of air,

It was once widely used as a lifting gas in balloons and airships.

The first hydrogen filled balloon was invented by Jacques Charles in 1783.

Hydrogen provided the lift for the first reliable form of air travel following the 1852 invention of the first hydrogen lifted airship by Henri Giffard.

German Count Ferdinand von Zeppelin promoted the idea of rigid airships lifted by hydrogen that later were called Zeppelins.

The first of which had its maiden flight in 1900.

Regularly scheduled flights started in 1910 and by the outbreak of World War I in August,

1914,

It carried 35,

000 passengers without a serious incident.

The first nonstop transit line at crossing was made by the British airship R34 in 1919 and regular passenger service resumed in the 1920s.

Deuterium was discovered in December,

1931 by Harold Ury and tritium was prepared in 1934 by Ernest Rutherford,

Mark Oliphant and Paul Hartig.

Heavy water,

Which consists of deuterium in the place of regular hydrogen was discovered by Ury's group in 1932.

H2 is relatively unreactive.

The thermodynamic basis of this low reactivity is the very strong H-H bond with a bond dissociation energy of 435.

7 kilojoules per mole.

It does form coordination complexes called dihydrogen complexes.

These species provide insights into the early steps in the interactions of hydrogen with metal catalysts.

According to neutron diffraction,

The metal and two H atoms form a triangle in these complexes.

The H-H bond remains intact,

But is elongated.

They are acidic.

Although exotic on earth,

The H plus three ion is common in the universe.

It is a triangular species like the aforementioned dihydrogen complexes.

It is known as protonated molecular hydrogen or the trihydrogen cation.

Hydrogen reacts with chlorine to produce HCl and with bromine to produce HBr by a chain reaction.

The reaction requires initiation.

For example,

In the case of Br2,

The diatomic molecule is broken into atoms,

Br2 plus ultraviolet light.

Light yields two Br atoms.

Propagating reactions consume hydrogen molecules and produce HBr as well as Br and H atoms.

Br plus hydrogen gas forms hydrogen bromide and a hydrogen atom.

A hydrogen atom and Br2 produces hydrogen bromide and a bromine atom.

Finally,

The terminating reaction,

A hydrogen atom and hydrogen bromide react to form hydrogen gas and a bromine atom.

Two bromine atoms combine to form Br2.

The addition of H2 to unsaturated organic compounds such as alkenes and alkynes is called hydrogenation.

Even if the reaction is energetically favorable,

It does not take place even at higher temperatures.

In the presence of a catalyst like finely divided platinum or nickel,

The reaction proceeds at room temperature.

Most known compounds contain hydrogen,

Not as H2,

But as covalently bonded H atoms.

This interaction is the basis of organic chemistry and biochemistry.

Hydrogen forms many compounds with carbon called the hydrocarbons.

Hydrocarbons are organic compounds.

In nature,

Organic compounds almost always contain heteroatoms such as nitrogen,

Oxygen,

And sulfur.

The study of their properties is known as organic chemistry and their study in the context of living organisms is called biochemistry.

By some definitions,

Organic compounds are only required to contain carbon.

However,

Most of them also contain hydrogen and because it is the carbon-hydrogen bond that gives this class of compounds most of its particular chemical characteristics,

Carbon-hydrogen bonds are required in some definitions of the word organic in chemistry.