What does letter H mean?
h, eighth letter of the alphabet. It corresponds to Semitic cheth and Greek eta (Η). It may derive from an early symbol for fence. In the early Greek alphabets a form with three horizontal bars and the simpler form H were both widely distributed.
How old is the letter H?
The word originally entered the language from French as autour, but around the 1500s, scribes started inserting the h and changed it into author. Scribes also put Hs on the beginning of words, even though the Hs remained silent, as in the words honest and historical.
What is H in ancient Greek?
Heta is a conventional name for the historical Greek alphabet letter Eta (Η) and several of its variants, when used in their original function of denoting the consonant /h/.
Why is H pronounced aitch?
The earlier Latin pronunciation is uncertain. And the name “aitch” for “h,” the OED says, goes back through the Middle English ache to the Old French and Spanish ache, then probably to the late Latin accha, ahha, or aha. The earlier Latin name was ha and the Greek name was heta.
How is H pronounced?
H, or h, is the eighth letter in the ISO basic Latin alphabet. Its name in English is aitch (pronounced /ˈeɪtʃ/, plural aitches), or regionally haitch /ˈheɪtʃ/....HUnicode codepointU+0048, U+0068Alphabetical position8HistoryDevelopmentΗ η 𐌇 H h15 more rows
How popular is the letter H?
English Letter Frequency (based on a sample of 40,000 words)LetterCountFrequencyS114506.28R109776.02H107955.92D78744.3222 more rows
What does Omicron mean in Latin?
little OThe word literally means "little O" (o mikron) as opposed to "great O" (ō mega).
What does Omicron mean in Greek?
little o“Omicron is the Greek for 'little o' (o mikron) as opposed to omega meaning 'great/big o'.
Is the letter H in the Greek alphabet?
The standard Greek alphabet doesn't include a separate letter for the H sound, even though many dialects of Greek had the sound. Instead two small marks called "breathing marks" are used.
Why do Americans say H differently?
Our American cousins seem sometimes to arbitrarily decide that they shall pronounce a word in the French style even if it has been an English word for nearly a thousand years. Thus they leave the "h" silent in herb, just as the French do.
How old is the letter J?
I understand that the letter "J" is relatively new — perhaps 400–500 years old.
Why do some people not pronounce the letter H?
H-dropping or aitch-dropping is the deletion of the voiceless glottal fricative or "H-sound", [h]. The phenomenon is common in many dialects of English, and is also found in certain other languages, either as a purely historical development or as a contemporary difference between dialects.
Overview
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula H2. It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter. Stars s…
Properties
Hydrogen gas (dihydrogen or molecular hydrogen) is highly flammable:
2 H2(g) + O2(g) → 2 H2O(l) + 572 kJ (286 kJ/mol)
The enthalpy of combustion is −286 kJ/mol.
Hydrogen gas forms explosive mixtures with air in concentrations from 4–74% and with chlorine at 5–95%. The explosive reactions may be triggered by spark…
History
In 1671, Robert Boyle discovered and described the reaction between iron filings and dilute acids, which results in the production of hydrogen gas. 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 called "phl…
Cosmic prevalence and distribution
Hydrogen, as atomic H, is the most abundant chemical element in the universe, making up 75 percent of normal matter by mass and more than 90 percent by number of atoms. (Most of the mass of the universe, however, is not in the form of chemical-element type matter, but rather is postulated to occur as yet-undetected forms of mass such as dark matter and dark energy. ) This element …
Production
H 2 is produced in chemistry and biology laboratories, often as a by-product of other reactions; in industry for the hydrogenation of unsaturated substrates; and in nature as a means of expelling reducing equivalents in biochemical reactions.
The electrolysis of water is a simple method of producing hydrogen. A current is run through the water, and gaseous oxygen forms at the anode while gaseous h…
Applications
Large quantities of H 2 are used in the "upgrading" of fossil fuels. Key consumers of H 2 include hydrodealkylation, hydrodesulfurization, and hydrocracking. Many of these reactions can be classified as hydrogenolysis, i.e., the cleavage of bonds to carbon. Illustrative is the separation of sulfur from liquid fossil fuels:
R-S-R + 2 H2 → H2S + 2 RH
Biological reactions
H2 is a product of some types of anaerobic metabolism and is produced by several microorganisms, usually via reactions catalyzed by iron- or nickel-containing enzymes called hydrogenases. These enzymes catalyze the reversible redox reaction between H2 and its component two protons and two electrons. Creation of hydrogen gas occurs in the transfer of reducing equivalents produced during pyruvate fermentation to water. The natural cycle of hydrog…
Safety and precautions
Hydrogen poses a number of hazards to human safety, from potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen-free form. In addition, liquid hydrogen is a cryogen and presents dangers (such as frostbite) associated with very cold liquids. Hydrogen dissolves in many metals and in addition to leaking out, may have adverse effects on them, such as hydrogen embrittlement, leading to cracks and explosions. Hydrogen gas leaking into externa…