Table Of Content
Thus, in the Old Italic alphabets, the letter Heta of the Euboean alphabet was adopted with its original sound value /h/. Essentially pure para-hydrogen can be produced by bringing the mixture into contact with charcoal at the temperature of liquid hydrogen; this converts all the ortho-hydrogen into para-hydrogen. The ortho-hydrogen, on the other hand, cannot be prepared directly from the mixture because the concentration of para-hydrogen is never less than 25 percent. A more accurate description of the hydrogen atom comes from a purely quantum mechanical treatment that uses the Schrödinger equation, Dirac equation or Feynman path integral formulation to calculate the probability density of the electron around the proton.[31] The most complicated treatments allow for the small effects of special relativity and vacuum polarization.
Energy carrier
Both of these forms result from writing the letter without taking the pen from the paper, the right-hand vertical bar being thus foreshortened and the horizontal stroke rounded. From these came the Carolingian form as well as the modern minuscule h. It consists of two protons and two electrons held together by electrostatic forces. Like atomic hydrogen, the assemblage can exist in a number of energy levels. Hydrogen is transparent to visible light, to infrared light, and to ultraviolet light to wavelengths below 1800 Å. Because its molecular weight is lower than that of any other gas, its molecules have a velocity higher than those of any other gas at a given temperature and it diffuses faster than any other gas.
English
The gas, however, was confused with other flammable gases, such as hydrocarbons and carbon monoxide. In 1766 Henry Cavendish, English chemist and physicist, showed that hydrogen, then called flammable air, phlogiston, or the flammable principle, was distinct from other combustible gases because of its density and the amount of it that evolved from a given amount of acid and metal. In 1781 Cavendish confirmed previous observations that water was formed when hydrogen was burned, and Antoine-Laurent Lavoisier, the father of modern chemistry, coined the French word hydrogène from which the English form is derived. In 1929 Karl Friedrich Bonhoeffer, a German physical chemist, and Paul Harteck, an Austrian chemist, on the basis of earlier theoretical work, showed that ordinary hydrogen is a mixture of two kinds of molecules, ortho-hydrogen and para-hydrogen. Because of the simple structure of hydrogen, its properties can be theoretically calculated relatively easily.
Meaning of H, h in English
The extremely low melting and boiling points result from weak forces of attraction between the molecules. The existence of these weak intermolecular forces is also revealed by the fact that, when hydrogen gas expands from high to low pressure at room temperature, its temperature rises, whereas the temperature of most other gases falls. According to thermodynamic principles, this implies that repulsive forces exceed attractive forces between hydrogen molecules at room temperature—otherwise, the expansion would cool the hydrogen. In fact, at −68.6° C attractive forces predominate, and hydrogen, therefore, cools upon being allowed to expand below that temperature. The cooling effect becomes so pronounced at temperatures below that of liquid nitrogen (−196° C) that the effect is utilized to achieve the liquefaction temperature of hydrogen gas itself. A molecular form called protonated molecular hydrogen (H+3) is found in the interstellar medium, where it is generated by ionization of molecular hydrogen from cosmic rays.
Biological reactions
The electrolysis of water is a conceptually simple method of producing hydrogen. The uppercase letter for H is H and the lowercase letter for H is h. The letter’s name is "haitch" (/ˈheɪtʃ/), also known as simply "'aitch" (/ˈeɪtʃ/). Sandra Liebenberg, Distinguished Professor and H F Oppenheimer Chair in Human Rights Law, Stellenbosch UniversityThis article is republished from The Conversation under a Creative Commons license. In pre-modern Maltese, h still produces the sound [h] as recorded by Agius de Soldanis (1750) and Mikel Anton Vassalli (1796).
In the quantum mechanical treatment, the electron in a ground state hydrogen atom has no angular momentum at all—illustrating how the "planetary orbit" differs from electron motion. In the early Greek alphabets a form with three horizontal bars and the simpler form H were both widely distributed. In Etruscan the prevailing form was similar to the early Greek form, and the same or a similar form occurs in very early Latin inscriptions, but the form H came into general use in Latin, either from the Chalcidic Greek alphabet of Cumae or from some other source. The cursive Latin form resembled a stylized version of the modern minuscule h, as did the uncial form.
Spanish
See the history of Polish orthography article on Wikipedia for more, and h for development of the glyph itself. See the Kashubian alphabet article on Wikipedia for more, and h for development of the glyph itself. In Basque, during the 20th century it was not used in the orthography of the Basque dialects in Spain but it marked an aspiration in the North-Eastern dialects.
It was formerly common for an rather than a to be used as the indefinite article before a word beginning with /h/ in an unstressed syllable, as in "an historian", but use of a is now more usual (see English articles § Indefinite article). Hydrogen is mainly produced by steam methane reforming (SMR), the reaction of water and methane.[103][104] [105] Thus, at high temperatures (1000–1400 K, 700–1100 °C or 1300–2000 °F), steam (water vapor) reacts with methane to yield carbon monoxide and H2. But whencesoever this stinking smoak proceeded, so inflammable it was, that upon the approach of a lighted candle to it, it would readily enough take fire, and burn with a blewish and somewhat greenish flame at the mouth of the viol for a good while together; and that, though with little light, yet with more strength than one would easily suspect. In the alphabets used to write the East Ionic dialect of Greek the letter became superfluous as a result of the disappearance of the aspirate which it represented in that dialect.
In lithium aluminium hydride, the [AlH4]− anion carries hydridic centers firmly attached to the Al(III). Throughout the universe, hydrogen is mostly found in the atomic and plasma states, with properties quite distinct from those of molecular hydrogen. As a plasma, hydrogen's electron and proton are not bound together, resulting in very high electrical conductivity and high emissivity (producing the light from the Sun and other stars). The charged particles are highly influenced by magnetic and electric fields.
During the standardization of Basque in the 1970s, the compromise was reached that h would be accepted if it were the first consonant in a syllable. Hence, herri ("people") and etorri ("to come") were accepted instead of erri (Biscayan) and ethorri (Souletin). For the dialects lacking the aspiration, this meant a complication added to the standardized spelling.
Note that it represents the sound of IPA [x] (like German machen, ach), not (as in most other alphabets based on the Latin script) the sound of IPA [h]. In English the initial h is pronounced in words of Germanic origin (e.g., hunt, hook); in some words of Romance origin, the h remains unpronounced (e.g., heir, honour), but in others it has been restored (e.g., humble, humour). The initial h often disappears in unaccented syllables (e.g., “What did he say?”). 'H' is also used in many spelling systems in digraphs and trigraphs, such as 'ch', which represents /tʃ/ in Spanish, Galician, and Old Portuguese; /ʃ/ in French and modern Portuguese; /k/ in Italian and French. Oxidation of hydrogen removes its electron and gives H+, which contains no electrons and a nucleus which is usually composed of one proton. Under the Brønsted–Lowry acid–base theory, acids are proton donors, while bases are proton acceptors.
See the Silesian language article on Wikipedia for more, and h for development of the glyph itself. In Irish, ⟨h⟩ is not considered an independent letter, except for a very few non-native words, however ⟨h⟩ placed after a consonant is known as a "séimhiú" and indicates lenition of that consonant; ⟨h⟩ began to replace the original form of a séimhiú, a dot placed above the consonant, after the introduction of typewriters. Its most important uses are in the digraphs 'ch' /k/ and 'gh' /ɡ/, as well as to differentiate the spellings of certain short words that are homophones, for example some present tense forms of the verb avere ('to have') (such as hanno, 'they have', vs. anno, 'year'), and in short interjections (oh, ehi).
No comments:
Post a Comment