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.

Origins tend to be " AT-rich " ( rich in adenine and thymine bases ) to assist this process, because A-T base pairs have two hydrogen bonds ( rather than the three formed in a C-G pair )— in general, strands rich in these nucleotides are easier to separate since less energy is required to break relatively fewer hydrogen bonds.

* 13. 6 eV: The energy required to ionize atomic hydrogen.

Unless that electricity is produced from a renewable source — and is not required for other purposes — hydrogen does not solve any energy crisis.

Dietary minerals are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen that are present in nearly all organic molecules.

Broadly speaking, it does not matter when they cut in or out, the hydrogen is simply stored and used as required.

About 50 kW · h ( 180 MJ ) of solar energy is required to produce a kilogram of hydrogen, so the cost of the electricity clearly is crucial, even for hydrogen uses other than storage for electrical generation.

Care is required in handling elemental sodium, as it is potentially explosive and generates inflammable hydrogen and caustic sodium hydroxide upon contact with water ; powdered sodium may combust spontaneously in air or oxygen.

The energy required to split water into hydrogen and oxygen by electrolysis or any other means is greater than the energy that can be collected when the hydrogen and oxygen recombine.

Only three other macronutrients are required by all plants: carbon, hydrogen, and oxygen.

On the other hand, the molecules in liquid water are held together by relatively strong hydrogen bonds, and its enthalpy of vaporization, 40. 65 kJ / mol, is more than five times the energy required to heat the same quantity of water from 0 ° C to 100 ° C ( c < sub > p </ sub > = 75. 3 J K < sup >− 1 </ sup > mol < sup >− 1 </ sup >).

Still, the lower thrust-to-weight ratio of nuclear thermal rockets versus chemical rockets ( which have thrust-to-weight ratios of 70: 1 ) and the large tanks necessary for liquid hydrogen storage mean that solid-core engines are best used in upper stages where vehicle velocity is already near orbital, in space " tugs " used to take payloads between gravity wells, or in launches from a lower gravity planet, moon or minor planet where the required thrust is lower.

41 tonnes of deuterium / tritium ( D-T ) fusion fuel would be required, plus 4124 tonnes of hydrogen expellant.

In addition to intra-and intermolecular hydrogen bonds, keratins have large amounts of the sulfur-containing amino acid cysteine, required for the disulfide bridges that confer additional strength and rigidity by permanent, thermally-stable crosslinking — a role sulfur bridges also play in vulcanized rubber.

The temperatures required to provide the nuclei with enough energy to overcome their repulsion is a function of the total charge, so hydrogen, which has the smallest nuclear charge therefore fuses at the lowest temperature.

In January 1965, the French thought the initial three-stage rocket design would not be sufficiently advanced to carry the size of payloads required, and another rocket-Eldo B-with liquid hydrogen as fuel for the second and third stages to be the better first design, partly due to reduce the cost of the project by eliminating transition test launchers.

The A-T and C-G pairings are required to match the hydrogen bonds between the amine and carbonyl groups on the complementary bases.

predicted that the alloy LiH < sub > 6 </ sub > would be a stable metal at only of the pressure required to metallize hydrogen, and that similar effects should hold for alloys of type LiH < sub > n </ sub > and possibly other alloys of type? Li < sub > n </ sub >.

If an exploration is required at a point too distant for the transportation of the inflated balloon, an additional apparatus for the generation of hydrogen gas will be required.

The drawbacks of hydrogen use are low energy content per unit volume, high tankage weights, very high storage vessel pressures, the storage, transportation and filling of gaseous or liquid hydrogen in vehicles, the large investment in infrastructure that would be required to fuel vehicles, and the inefficiency of production processes.

So be it -- then we must embark on a crash program for 200-megaton bombs of the common or hydrogen variety, and neutron bombs, which do not exist but are said to be the coming thing.

A study of the hydrogen line profiles indicates that a measurement of these profiles can be used to calculate a temperature for the arc plasma that is reliable to about Af percent.

Af appeared to be well suited for the study of these matters, since it is a normal paramagnet, with three unpaired electrons on the chromium, its crystal structure is very simple, and the unknown position of the hydrogen in the strong Af bond provides structural interest.

If the Af bond is linear then there are three reasonable positions for the hydrogen atoms: ( 1 ) The hydrogen atoms are centered and hence all lie on a sheet midway between the oxygen sheets ; ;

A randomization of `` ups '' and `` downs '' is more likely than ordered `` ups '' and `` downs '' in position ( 3 ) since the hydrogen atoms are well separated and so the position of one could hardly affect the position of another, and also since ordered `` up '' and `` down '' implies a larger unit cell, for which no evidence exists.

water is Af and the H stands for hydrogen ; ;

With just the hydrogen of our bodies, we could run the world for years.

For new galaxies to be created, Professor Bondi declares, it would only be necessary for a single hydrogen atom to be created in an area the size of your living room once every few million years.

An alkyl group, generally abbreviated with the symbol R, is a functional group or side-chain that, like an alkane, consists solely of single-bonded carbon and hydrogen atoms, for example a methyl or ethyl group.

The stronger of two acids will have a higher K < sub > a </ sub > than the weaker acid ; the ratio of hydrogen ions to acid will be higher for the stronger acid as the stronger acid has a greater tendency to lose its proton.

Thus, for hydrogen chloride, the IUPAC name would be aqueous hydrogen chloride.

All other nuclides ( isotopes of hydrogen and all other elements ) have more nucleons than electrons, so the fraction of mass taken by the nucleus is closer to 100 % for all of these types of atoms, than for hydrogen-1 .</ ref > with protons and neutrons having roughly equal mass.

The three " R's " stand for carbon substituents or hydrogen atoms.

With de Broglie's suggestion of the existence of electron matter waves in 1924, and for a short time before the full 1926 Schrödinger equation treatment of hydrogen like atom, a Bohr electron " wavelength " could be seen to be a function of its momentum, and thus a Bohr orbiting electron was seen to orbit in a circle at a multiple of its half-wavelength ( this historically incorrect Bohr model is still occasionally taught to students ).

The simplest atomic orbitals are those that are calculated for systems with a single electron, such as the hydrogen atom.

Lavoisier discovered that Henry Cavendish's " inflammable air ," which Lavoisier had termed hydrogen ( Greek for " water-former "), combined with oxygen to produce a dew which, as Joseph Priestley had reported, appeared to be water.

Deuterium HCL or even hydrogen HCL and deuterium discharge lamps are used in LS AAS for background correction purposes.

The remaining sp orbital on each atom can form a sigma bond to another atom, for example to hydrogen atoms in the parent acetylene.

The Arrhenius definition of acid – base reactions is a development of the hydrogen theory of acids, devised by Svante Arrhenius, which was used to provide a modern definition of acids and bases that followed from his work with Friedrich Wilhelm Ostwald in establishing the presence of ions in aqueous solution in 1884, and led to Arrhenius receiving the Nobel Prize in Chemistry in 1903 for " recognition of the extraordinary services ... rendered to the advancement of chemistry by his electrolytic theory of dissociation ".

Just six elements — carbon, hydrogen, nitrogen, oxygen, calcium, and phosphorus — make up almost 99 % of the mass of a human body ( see composition of the human body for a complete list ).

Purines are complementary only with pyrimidines: pyrimidine-pyrimidine pairings are energetically unfavorable because the molecules are too far apart for hydrogen bonding to be established ; purine-purine pairings are energetically unfavorable because the molecules are too close, leading to overlap repulsion.