Table Of Content
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.
In other languages
In most dialects of Polish, both ⟨h⟩ and the digraph ⟨ch⟩ always represent /x/. In Ukrainian and Belarusian, when written in the Latin alphabet, ⟨h⟩ is also commonly used for /ɦ/, which is otherwise written with the Cyrillic letter ⟨г⟩. Steam reforming is also used for the industrial preparation of ammonia.
Words That Start With H
The original Semitic letter Heth most likely represented the voiceless pharyngeal fricative (ħ). The first non-stop transatlantic crossing was made by the British airship R34 in 1919. Regular passenger service resumed in the 1920s and the discovery of helium reserves in the United States promised increased safety, but the U.S. government refused to sell the gas for this purpose. Therefore, H2 was used in the Hindenburg airship, which was destroyed in a midair fire over New Jersey on 6 May 1937.[8] The incident was broadcast live on radio and filmed.
Mr. John H. Lovelady, Jr. Funeral Notices - Fayette County News
Mr. John H. Lovelady, Jr. Funeral Notices.
Posted: Thu, 02 May 2024 13:10:00 GMT [source]
Derived terms
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.
A Brief History Of The Letter H
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).
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.
The early contemporary variant was first found in the dialect of lsien tal-bliet (“tongues of the cities”, referring to the cities around the Grand Harbour according to Vassalli) which eventually superceded the increasingly archaic [h] sound in the neighborhing areas.
Role in quantum theory
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.
Physical and chemical properties
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.
For example, in Italian h is used in combination with c or g to indicate the hard sound before a front vowel (e.g., chi, ghetto). The Greek Eta 'Η' in archaic Greek alphabets, before coming to represent a long vowel, /ɛː/, still represented a similar sound, the voiceless glottal fricative /h/. In this context, the letter eta is also known as Heta to underline this fact.
Even though it is often said that there are more known compounds of carbon than of any other element, the fact is that, since hydrogen is contained in almost all carbon compounds and also forms a multitude of compounds with all other elements (except some of the noble gases), it is possible that hydrogen compounds are more numerous. Compounds of hydrogen are often called hydrides, a term that is used fairly loosely. The term "hydride" suggests that the H atom has acquired a negative or anionic character, denoted H−, and is used when hydrogen forms a compound with a more electropositive element. The existence of the hydride anion, suggested by Gilbert N. Lewis in 1916 for group 1 and 2 salt-like hydrides, was demonstrated by Moers in 1920 by the electrolysis of molten lithium hydride (LiH), producing a stoichiometric quantity of hydrogen at the anode.[50] For hydrides other than group 1 and 2 metals, the term is quite misleading, considering the low electronegativity of hydrogen.
It was accordingly put to a new use to indicate the open long e which had arisen through alteration of the primitive Greek long a. In a few inscriptions from Thera, Naxos, and several other localities the letter was used with syllabic value; that is, it included he, thus showing its old consonantal and its new vocalic value at the same time. Eventually, as a result of the spread of the Ionic alphabet, its use for the long vowel e or η became general throughout Greece, while its consonantal value as the aspirate h passed from the western Greek alphabets into the Etruscan alphabets and then into the Latin and other alphabets of ancient Italy. In the Romance languages the sound has largely disappeared, but the letter is still extensively used, partly with only etymological value, (e.g., French homme), partly with fancied etymological value (e.g., French haut from Latin altus, with h through the influence of hoh, the Old High German word of the same meaning), partly with special orthographical functions.
The two forms may, however, interconvert under certain conditions. Equilibrium between the two forms can be established in several ways. One of these is by the introduction of catalysts (such as activated charcoal or various paramagnetic substances); another method is to apply an electrical discharge to the gas or to heat it to a high temperature. In Spanish and Portuguese, ⟨h⟩ is a silent letter with no pronunciation, as in hijo [ˈixo] ('son') and húngaro [ˈũɡaɾu] ('Hungarian'). In words where the ⟨h⟩ is derived from a Latin /f/, it is still sometimes pronounced with the value [h] in some regions of Andalusia, Extremadura, Canarias, Cantabria, and the Americas. Some words beginning with [je] or [we], such as hielo, 'ice' and huevo, 'egg', were given an initial ⟨h⟩ to avoid confusion between their initial semivowels and the consonants ⟨j⟩ and ⟨v⟩.
Hence hydrogen is often used as a theoretical model for more complex atoms, and the results are applied qualitatively to other atoms. These differ in the magnetic interactions of the protons due to the spinning motions of the protons. In ortho-hydrogen, the spins of both protons are aligned in the same direction—that is, they are parallel. In para-hydrogen, the spins are aligned in opposite directions and are therefore antiparallel. The relationship of spin alignments determines the magnetic properties of the atoms. Normally, transformations of one type into the other (i.e., conversions between ortho and para molecules) do not occur and ortho-hydrogen and para-hydrogen can be regarded as two distinct modifications of hydrogen.
No comments:
Post a Comment