Trivial name

In chemistry, a trivial name is a nonsystematic name for a chemical substance. That is, the name is not recognized according to the rules of any formal system of chemical nomenclature such as IUPAC inorganic or IUPAC organic nomenclature. A trivial name is not a formal name and is usually a common name.

Generally, trivial names are not useful in describing the essential properties of the thing being named. Properties such as the molecular structure of a chemical compound are not indicated. And, in some cases, trivial names can be ambiguous or will carry different meanings in different industries or in different geographic regions. (For example, a trivial name such as white metal can mean various things.) On the other hand, systematic names can be so convoluted and difficult to parse that their trivial names are preferred. As a result, a limited number of trivial chemical names are retained names, an accepted part of the nomenclature.

Trivial names often arise in the common language; they may come from historic usages in, for example, alchemy. Many trivial names pre-date the institution of formal naming conventions. Names can be based on a property of the chemical, including appearance (color, taste or smell), consistency, and crystal structure; a place where it was found or where the discoverer comes from; the name of a scientist; a mythological figure; an astronomical body; the shape of the molecule; and even fictional figures. All elements that have been isolated have trivial names.

The element mercury was named after the Roman god (painting by Hendrik Goltzius).


In scientific documents, international treaties, patents and legal definitions, names for chemicals are needed that identify them unambiguously. This need is satisfied by systematic names. One such system, established by the International Union of Pure and Applied Chemistry (IUPAC), was established in 1950. Other systems have been developed by the American Chemical Society, the International Organization for Standardization, and the World Health Organization. However, chemists still use many names that are not systematic because they are traditional or because they are more convenient than the systematic names. These are called trivial names. The word "trivial", often used in a pejorative sense, was intended to mean "commonplace".[1]

In addition to trivial names, chemists have constructed semi-trivial names by appending a standard symbol to a trivial stem.[2] Some trivial and semi-trivial names are so widely used that they have been officially adopted by IUPAC; these are known as retained names.


Traditional names of elements are trivial, some originating in alchemy. IUPAC has accepted these names, but has also defined systematic names of elements that have not yet been prepared. It has adopted a procedure by which the scientists who are credited with preparing an element can propose a new name. Once the IUPAC has accepted such a (trivial) name, it replaces the systematic name.[1]


ASM ytterbymine
A plaque commemorating a mine in Ytterby where ore was obtained from which four new elements were isolated.
Pierre Curie et Marie Sklodowska Curie 1895
Curium was named after Pierre and Marie Sklodowska Curie.

Nine elements were known by the Middle Agesgold, silver, tin, mercury, copper, lead, iron, sulfur, and carbon.[3] Mercury was named after the planet, but its symbol was derived from the Latin hydrargyrum, which itself comes from the greek υδράργυρος, meaning liquid silver; mercury is also known as quicksilver in English.[1] The symbols for the other eight are also derived from descriptions of their properties in Latin.[3]

Systematic nomenclature began after Louis-Bernard Guyton de Morveau stated the need for “a constant method of denomination, which helps the intelligence and relieves the memory”.[4] The resulting system was popularized by Antoine Lavoisier's publication of Méthode de nomenclature chimique (Method of Chemical Nomenclature) in 1787. Lavoisier proposed that elements be named after their properties. For the next 125 years, most chemists followed this suggestion, using Greek and Latin roots to compose the names; for example, hydrogen ("water-producing"), oxygen ("acid-producing"), nitrogen ("soda-producing"), bromine ("stink"), and argon ("no reaction") were based on Greek roots, while the names of iodine and chlorine were derived from the Greek words for their characteristic colors. Indium, rubidium, and thallium were similarly named for the colors of particular lines in their emission spectra. Iridium, which forms compounds of many different colors, takes its name from iris, the Latin for "rainbow".[3] The noble gases have all been named for their origin or properties. Helium comes from the Greek helios, meaning "sun" because it was first detected as a line in the spectrum of the sun (it is not known why the suffix -ium, which is used for metals, was chosen).[5] The other noble gases are neon ("new"), argon ("slow, lazy"), krypton ("hidden"), xenon ("stranger"), and radon ("from radium").[6]

Many more elements have been given names that have little or nothing to do with their properties. Elements have been named for celestial bodies (helium, selenium, tellurium, for the sun, moon, and earth; cerium and palladium for Ceres and Pallas, two asteroids). They have been named for mythological figures, including Titans in general (titanium) and Prometheus in particular (promethium); Roman and Greek gods (uranium, neptunium, and plutonium) and their descendents (tantalum for Tantalus, a son of Zeus, and niobium for Niobe, a daughter of Tantalus); and Norse deities (vanadium for the goddess Vanadis and thorium for the god Thor).[6]

Some elements were named for aspects of the history of their discovery. In particular, technetium and promethium were so named because the first samples detected were artificially synthesised; neither of the two has any isotope sufficiently stable to occur in nature on Earth in significant quantities. The connection to the Titan Prometheus was that he had been fabled to have stolen fire from the gods for mankind.

Discoverers of some elements named them after their home country or city. Marie Curie named polonium after Poland; ruthenium, gallium, germanium, and lutetium were based on the Latin names for Russia, France, Germany, and Paris. Other elements are named after the place where they were discovered. Four elements, terbium, erbium, ytterbium, and yttrium were named after a Swedish village Ytterby, where ores containing them were extracted.[3] Other elements named after places are magnesium (after Magnesia), strontium, scandium, europium, thulium (after an old Roman name for the far north of Scandinavia), holmium, copper (derived from Cyprus, where it was mined in the Roman era), hafnium, rhenium, americium, berkelium, californium, and darmstadtium.[6]

For the elements up to 92 (uranium), naming elements after people was discouraged. The two exceptions are indirect, the elements being named after minerals that were themselves named after people. These were gadolinium (found in gadolinite, named after the Finnish chemist Johan Gadolin) and samarium (the mineral samarskite was named after a Russian mining engineer, Vasili Samarsky-Bykhovets). Among the transuranium elements, this restriction was relaxed, there followed curium (after the Curies), einsteinium, fermium (Enrico Fermi), mendelevium (Dmitri Mendeleev), nobelium (Alfred Nobel), and lawrencium (after Ernest Lawrence).[6][7]:320

Relation to IUPAC standards

IUPAC has established international standards for naming elements. The first scientist or laboratory to isolate an element has the right to propose a name; after a review process, a final decision is made by the IUPAC Council. In keeping with tradition, names can be based on a mythological concept or character, astronomical object, mineral, place, property of the element or scientist.[4] For those elements that have not yet been discovered, IUPAC has established a systematic name system. The names combine syllables that represent the digits of the atomic number, followed by "-ium". For example, "unununium" is element 111 ("un" being the syllable for 1).[8] However, once the element has been found, the systematic name is replaced by a trivial one, in this case roentgenium.[1]

The IUPAC names for elements are intended for use in the official languages. At the time of the first edition of the IUPAC Red Book (which contains the rules for inorganic compounds), those languages were English and French; now English is the sole official language.[9] However, other languages still have their own names for elements. The chemical symbol for tungsten, W, is based on the German name wolfram, which is found in wolframite and comes from the German for "wolf's foam", how the mineral was known to Saxon miners. The name tungsten means "heavy stone", a description of scheelite, another mineral in which tungsten is found.[10] The German names for hydrogen, oxygen, and nitrogen are Wasserstoff (water substance), Sauerstoff (acid substance), and Stickstoff (smothering substance). Russian names for hydrogen, oxygen and carbon are "vodorod", "kislorod" and "uglerod" (generating water, acid and coal respectively). The corresponding Chinese names are qīngqì (light gas), yǎngqì (nourishing gas), and dànqì (diluting gas). A scheme for translating chemical names into Chinese was developed by John Fryer and Xu Shou in 1871. Where traditional names were well established, they kept them; otherwise, a single character for a name was compounded out of one of the five xing (phases) – metal, wood, water, fire, and earth – and a sound from the English name of the element.[11]

Inorganic chemistry

Hematite-rich BIF ventifact
Red hematite-rich sample from a banded iron formation in Wyoming.

Early terminology for compound chemicals followed similar rules to the naming of elements. The names could be based on the appearance of the substance, including all five senses. In addition, chemicals were named after the consistency, crystalline form, a person or place, its putative medical properties or method of preparation.[12]:68

Salt (sodium chloride) is soluble and is used to enhance the taste of food. Substances with similar properties came to be known as salts, in particular Epsom salt (magnesium sulfate, found in a bitter saline spring in the English town of Epsom). Ammonium (with the little-used formal name nitrogen trihydride) was first extracted from sal ammoniac, meaning "salt of Amun". Ancient Romans noticed crystals of it in Egyptian temples devoted to the god Amun; the crystals had condensed from the smoke of burning camel dung.[13] Lead acetate was called sugar of lead.[12]:70,77–78 However, other names like sugar of lead (lead(II) acetate), butter of antimony (antimony trichloride), oil of vitriol (sulfuric acid), and cream of tartar (potassium bitartrate) borrowed their language from the kitchen.[12]:65–66 Many more names were based on color; for example, hematite, orpiment, and verdigris come from words meaning "blood-like stone", "gold pigment", and "green of Greece".[12]:70

Some names are based on their use. Lime is a general name for materials combining calcium with carbonates, oxides or hydroxides; the name comes from a root "sticking or adhering"; its earliest use was as mortar for construction.[14]

Water has several systematic names, including oxidane (the IUPAC name), hydrogen oxide, and dihydrogen monoxide (DHMO). The latter was the basis of the dihydrogen monoxide hoax, a document that was circulated warning readers of the dangers of the chemical (for example, it is fatal if inhaled).[15][16]

Organic chemistry

In organic chemistry, some trivial names derive from a notable property of the thing being named. For instance, lecithin, the common name for phosphatidylcholine, was originally isolated from egg yolk. The word is coined from the Greek λέκιθος (lékithos) for yolk.[17][18]

Many trivial names continue to be used because their sanctioned equivalents are considered too cumbersome for everyday use. For example, "tartaric acid", a compound found in wine, has a systematic name of 2,3-dihydroxybutanedioic acid. The pigment β-Carotene has an IUPAC name of 1,3,3-trimethyl-2-[(1E,3E,5E,7E,9E,11E,13E,15E,17E)-3,7,12,16-tetramethyl-18-(2,6,6-trimethylcyclohexen-1-yl)octadeca-1,3,5,7,9,11,13,15,17-nonaenyl]cyclohexene.[19] However, the trivial name can be potentially confusing. Based on its name, one might come to the conclusion that the molecule theobromine contains one or more bromine atoms. In reality it is an alkaloid similar in structure to caffeine.


Several organic molecules have semitrivial names where the suffixes -ane (for an alkane) or -ene (for an alkene) are added to a name based on the shape of the molecule.[7]:xi Some are pictured below. Other examples include barrelene (shaped like a barrel),[7]:58 fenestrane (having a window-pane motif),[7]:55 ladderane (a ladder shape), olympiadane (having a shape with the same topology as the Olympic rings) and quadratic acid (also known as squaric acid).

Based on fiction

Rodolfo from La Boheme (1896)
The antibiotic Rudolphomycin is named after the character Rodolfo from the opera La Bohème.

The Bohemic acid complex is a mixture of chemicals obtained through fermentation of a species of actinobacteria. In 1977 the components were isolated and have been found useful as antitumor agents and anthracycline antibiotics. The authors named the complex (and one of its components, bohemamine) after the opera La bohème by Puccini, and the remaining components were named after characters in the opera: alcindoromycin (Alcindoro), collinemycin (Colline), marcellomycin (Marcello), mimimycin (Mimi), musettamycin (Musetta), rudolphomycin (Rodolfo) and schaunardimycin (Schaunard).[7]:64[20] However, the relationships between the characters do not correctly reflect the chemical relationships.[21]

A research lab at Lepetit Pharmaceuticals, led by Piero Sensi, was fond of coining nicknames for chemicals that they discovered, later converting them to a form more acceptable for publication. The antibiotic Rifampicin was named after a French movie, Rififi, about a jewel heist. They nicknamed another antibiotic "Mata Hari" before changing the name to Matamycin.[21]

See also


  1. ^ a b c d Leigh 2012
  2. ^ Smith, Peter A. S. (1992). "Trivial names for chemical substances: Will they be taught or forgotten in the twenty-first century?". Journal of Chemical Education. 69 (11): 877. Bibcode:1992JChEd..69..877S. doi:10.1021/ed069p877.
  3. ^ a b c d Davis, Raymond E.; Stanley, George G.; Peck, Larry M. (2007). "Names of the elements". In Whitten, Kenneth W. (ed.). Chemistry (8th ed.). Belmont: Thomson Brooks/Cole. pp. 64–65. ISBN 9780495011965.
  4. ^ a b Koppenol, W. H. (2002). "Naming of new elements (IUPAC Recommendations 2002)". Pure and Applied Chemistry. 74 (5): 787–791. doi:10.1351/pac200274050787.
  5. ^ Jensen, William B. (2004). "Why Helium Ends in "-ium"" (PDF). Journal of Chemical Education. 81: 81–82. Bibcode:2004JChEd..81..944J. doi:10.1021/ed081p944. Retrieved 4 November 2013.
  6. ^ a b c d Enghag, Per (2004). "7.1. Element names". Encyclopedia of the Elements Technical Data - History - Processing - Applications. Weinheim: Wiley-VCH. pp. 71–78. ISBN 9783527612345.
  7. ^ a b c d e Nickon & Silversmith 1987
  8. ^ Chatt, J. (1979). "Recommendations for the Naming of Elements of Atomic Numbers Greater than 100". Pure and Applied Chemistry. 51: 381–384. doi:10.1351/pac197951020381. Retrieved 4 November 2013.
  9. ^ Damhus, Ture (July–August 2005). "Reply to 'Wolfram vs. Tungsten' by Pilar Goya and Pascual Román". Chemistry International. 27 (4). Retrieved 4 November 2013.
  10. ^ Goya, Piler; Román, Pascual (July–August 2005). "Wolfram vs. Tungsten". Chemistry International. 27 (4). Retrieved 4 November 2013.
  11. ^ Hao, Chang (January–February 2004). "Chinese Terms for Chemical Elements: Characters Combining Radical and Phonetic Elements". Chemistry International. 26 (1). Retrieved 4 November 2013.
  12. ^ a b c d Crosland, Maurice P. (2004). Historical studies in the language of chemistry (First published in 1978; 2004 reprint ed.). Mineola, N.Y.: Dover Publications. ISBN 9780486438023.
  13. ^ Lower, Stephen. "Naming chemical substances". General Chemistry Virtual Textbook. Retrieved 6 November 2013.
  14. ^ Harper, Douglas (2001–2013). "lime (n.1)". Online etymology dictionary. Retrieved 4 November 2013.
  15. ^ Kruszelnicki, Karl S. (17 May 2006). "Mysterious killer chemical". ABC Science. America Broadcasting Corporation. Retrieved 5 November 2013.
  16. ^ Craig Jackson (1994), Ban Dihydrogen Monoxide!, Coalition to ban DHMO, archived from the original on 1996-10-31. Coalition to ban DHMO officers, Coalition to ban DHMO, archived from the original on 1997-01-25.
  17. ^ Dalmeijer, GW; Olthof, MR; Verhoef, P; Bots, ML; van der Schouw, YT (2008). "Prospective study on dietary intakes of folate, betaine, and choline and cardiovascular disease risk in women". European Journal of Clinical Nutrition. 62 (3): 386–94. doi:10.1038/sj.ejcn.1602725. PMID 17375117.
  18. ^ Gobley, Nicolas Theodore (1874). "Sur la lécithine et la cérébrine". Journal de Pharmacie et de Chimie: t20, 98–103, 161–166.
  19. ^ "beta Carotene - Compound Summary". PubChem Compound. National Center for Biotechnology Information. Retrieved 10 November 2013.
  20. ^ Nettleton, Donald E.; Balitz, David M.; Doyle, Terrence W.; Bradner, William T.; Johnson, David L.; O'Herron, Frances A.; Schreiber, Richard H.; Coon, Alonzo B.; Moseley, John E.; Myllymaki, Robert W. (1980). "Antitumor Agents From Bohemic Acid Complex, III. The Isolation of Marcellomycin, Musettamycin, Rudolphomycin, Mimimycin, Collinemycin, Alcindoromycin, and Bohemamine". Journal of Natural Products. 43 (2): 242–258. doi:10.1021/np50008a003. PMID 7381507.
  21. ^ a b Aronson, Jeff (1999). "That's show business". British Medical Journal. BMJ Group. 319 (7215): 972. doi:10.1136/bmj.319.7215.972. PMC 1116803. PMID 10514162.

Further reading

  • Andraos, John. "Glossary of Coined Names & Terms Used in Science" (PDF). Retrieved 3 November 2013.
  • Irving, H. M. N. H. (1978). "Guide to trivial names, trade names and synonyms for substances used in analytical nomenclature" (PDF). Pure and Applied Chemistry. 50: 338–370. doi:10.1016/b978-0-08-022382-7.50003-6. Archived from the original (PDF) on 4 March 2016. Retrieved 3 November 2013.
  • Koppenol, W. H. (2002). "Naming of new elements (IUPAC Recommendations 2002)". Pure and Applied Chemistry. 74 (5): 787–791. doi:10.1351/pac200274050787.
  • Leigh, G. J. Principles of chemical nomenclature : a guide to IUPAC recommendations (2011 ed.). Cambridge: Royal Society of Chemistry. ISBN 9781849730075.
  • Leigh, Jeffrey (2012). "Systematic and Trivial Nomenclature". Chemistry International. 34 (5). Retrieved 3 November 2013.
  • May, Paul W. (2008). Molecules with silly or unusual names. London: Imperial College Press. ISBN 978-1-84816-207-5.
  • Nickon, Alex; Silversmith, Ernest F. (1987). Organic Chemistry, the Name Game: Modern Coined Terms and Their Origins. Pergamon. ISBN 0-08-034481-X.
  • Sonneveld, W. B.; Loening, K. L. (1988). "A terminologist's and a chemist's look at chemical neologisms". In Strehlow, Richard A. (ed.). Standardization of technical terminology : principles and practices (second volume). Philadelphia, PA: ASTM STP 991. pp. 23–28. ISBN 9780803111837.

External links

ARPA Host Name Server Protocol

The ARPA Host Name Server Protocol (NAMESERVER), is an obsolete network protocol used in translating a host name to an Internet address. IANA Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) port 42 for NAMESERVER; this port is more commonly used by the Windows Internet Name Service (WINS) on Microsoft operating systems.


Asafoetida (; also spelled asafetida) is the dried latex (gum oleoresin) exuded from the rhizome or tap root of several species of Ferula (F. foetida and F. assa-foetida), perennial herbs growing 1 to 1.5 m (3.3 to 4.9 ft) tall. They are part of the celery family, Umbelliferae. Notably, asafoetida is thought to be in the same genus as silphium, a North African plant now believed to be extinct, and was used as a cheaper substitute for that historically important herb from classical antiquity. The species are native to the deserts of Iran and mountains of Afghanistan, but are mainly cultivated in nearby Pakistan and India.Asafoetida has a pungent smell, lending it the trivial name of stinking gum, but in cooked dishes it delivers a smooth flavour reminiscent of leeks or other onion relatives. Asafoetida is also known variously as "food of the gods", "devil's dung", jowani badian, hing, hengu, inguva, kayam, and ting.


Benzidine (trivial name), also called 1,1'-biphenyl-4,4'-diamine (systematic name), is an organic compound with the formula (C6H4NH2)2. It is an aromatic amine. It is a component of a test for cyanide. Related derivatives are used in the production of dyes. Benzidine has been linked to bladder and pancreatic cancer.


In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula HCO−3.

Bicarbonate serves a crucial biochemical role in the physiological pH buffering system.The term "bicarbonate" was coined in 1814 by the English chemist William Hyde Wollaston. The prefix "bi" in "bicarbonate" comes from an outdated naming system and is based on the observation that there is twice as much carbonate (CO2−3) per sodium ion in sodium bicarbonate (NaHCO3) and other bicarbonates than in sodium carbonate (Na2CO3) and other carbonates. The name lives on as a trivial name.

Common name

In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, trivial name, trivial epithet, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; this kind of name is often contrasted with the scientific name for the same organism, which is Latinized. A common name is sometimes frequently used, but that is by no means always the case.Sometimes common names are created by authorities on one particular subject, in an attempt to make it possible for members of the general public (including such interested parties as fishermen, farmers, etc.) to be able to refer to one particular species of organism without needing to be able to memorise or pronounce the Latinized

scientific name. Creating an "official" list of common names can also be an attempt to standardize the use of common names, which can sometimes vary a great deal between one part of a country and another, as well as between one country and another country, even where the same language is spoken in both places.


Corrinoids are a group of compounds based on the skeleton of corrin, a cyclic system containing four pyrrole rings similar to porphyrins. These include compounds based on octadehydrocorrin, which has the trivial name corrole.The cobalamins (vitamin B12) are the best known members of the group. Other prominent examples include cobyrinic acid and its hexaamide cobyric acid; cobinic acid and its hexaamide cobinamide; cobamic acid and cobamide.

Compounds containing the "Cob-" prefix (not corrin) are cobalt derivatives, and may include an oxidation state, as in "Cob(II)alamin". When cobalt is replaced by another metal or hydrogen, the name changes accordingly, as in ferrobamic acid or hydrogenobamic acid.


Dicoronylene is the trivial name for a very large polycyclic aromatic hydrocarbon. Its formal name is benzo[10,11]phenanthro[2',3',4',5',6':4,5,6,7]chryseno[1,2,3-bc]coronene (IUPAC name) or benzo[1,2,3-bc:4,5,6-b'c']dicoronene (name sometimes used in Chemical Abstracts). It has 15 rings and is a brick-red solid. Its formula is C48H20. Dicoronylene sublimes under high vacuum, 0.001 torr, between 250 °C and 300 °C.

Docosahexaenoic acid

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. In physiological literature, it is given the name 22:6(n-3). It can be synthesized from alpha-linolenic acid or obtained directly from maternal milk (breast milk), fish oil, or algae oil.DHA's structure is a carboxylic acid (-oic acid) with a 22-carbon chain (docosa- derives from the Ancient Greek for 22) and six (hexa-) cis double bonds (-en-); with the first double bond located at the third carbon from the omega end. Its trivial name is cervonic acid, its systematic name is all-cis-docosa-4,7,10,13,16,19-hexa-enoic acid, and its shorthand name is 22:6(n−3) in the nomenclature of fatty acids.

Most of the DHA in fish and multi-cellular organisms with access to cold-water oceanic foods originates from photosynthetic and heterotrophic microalgae, and becomes increasingly concentrated in organisms the further they are up the food chain. DHA is also commercially manufactured from microalgae: Crypthecodinium cohnii and another of the genus Schizochytrium. DHA manufactured using microalgae is vegetarian.In organisms that do not eat algae containing DHA nor animal products containing DHA, DHA is instead produced internally from α-linolenic acid, a shorter omega-3 fatty acid manufactured by plants (and also occurring in animal products as obtained from plants). Limited amounts of eicosapentaenoic and docosapentaenoic acids are possible products of α-linolenic acid metabolism in young women and men. DHA in breast milk is important for the developing infant. Rates of DHA production in women are 15% higher than in men.DHA is a major fatty acid in brain phospholipids and the retina. While the potential roles of DHA in the mechanisms of Alzheimer's disease are under active research, studies of fish oil supplements, which contain DHA, have failed to support claims of preventing cardiovascular diseases.

Eicosapentaenoic acid

Eicosapentaenoic acid (EPA; also icosapentaenoic acid) is an omega-3 fatty acid. In physiological literature, it is given the name 20:5(n-3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid with a 20-carbon chain and five cis double bonds; the first double bond is located at the third carbon from the omega end.

EPA is a polyunsaturated fatty acid (PUFA) that acts as a precursor for prostaglandin-3 (which inhibits platelet aggregation), thromboxane-3, and leukotriene-5 eicosanoids. EPA is both a precursor and the hydrolytic breakdown product of eicosapentaenoyl ethanolamide (EPEA: C22H35NO2; 20:5,n-3). Although studies of fish oil supplements, which contain both docosahexaenoic acid (DHA) and EPA, have failed to support claims of preventing heart attacks or strokes, a recent multi-year study of Vascepa (ethyl eicosapentaenoic acid), a prescription drug containing only EPA, was shown, with incredibly high statistical significance (p<.00000001), to reduce heart attack, stroke, and cardiovascular death by 26% relative to a placebo.

Enzyme Commission number

The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. As a system of enzyme nomenclature, every EC number is associated with a recommended name for the respective enzyme.

Strictly speaking, EC numbers do not specify enzymes, but enzyme-catalyzed reactions. If different enzymes (for instance from different organisms) catalyze the same reaction, then they receive the same EC number. Furthermore, through convergent evolution, completely different protein folds can catalyze an identical reaction and therefore would be assigned an identical EC number (these are called non-homologous isofunctional enzymes, or NISE). By contrast, UniProt identifiers uniquely specify a protein by its amino acid sequence.


Ethers are a class of organic compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula R–O–R′, where R and R′ represent the alkyl or aryl groups. Ethers can again be classified into two varieties: if the alkyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether" (CH3–CH2–O–CH2–CH3). Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin.

Group (periodic table)

In chemistry, a group (also known as a family) is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table, and the f-block columns (between groups 3 and 4) are not numbered. The elements in a group have similar physical or chemical characteristics of the outermost electron shells of their atoms (i.e., the same core charge), as most chemical properties are dominated by the orbital location of the outermost electron.

There are three systems of group numbering for the groups, that often assign the same number to different groups. The modern numbering "group 1" to "group 18" has been recommended by the International Union of Pure and Applied Chemistry (IUPAC) since about 1990. It replaces two older incompatible naming schemes, used by the Chemical Abstract Service (CAS, more popular in the U. S.), and by IUPAC before 1990 (more popular in Europe).

Groups may also be identified by their topmost element or have a specific name. For example, group 16 is variously described as the "oxygen group" and as the "chalcogens". However, iron group usually does not mean "group 8". In chemistry it may mean either iron, cobalt, and nickel, or some other set of elements with similar chemical properties. In astrophysics and nuclear physics, it usually means those three plus chromium and manganese.

Group 4 element

Group 4 is a group of elements in the periodic table.

It contains the elements titanium (Ti), zirconium (Zr), hafnium (Hf) and rutherfordium (Rf). This group lies in the d-block of the periodic table. The group itself has not acquired a trivial name; it belongs to the broader grouping of the transition metals.

The three Group 4 elements that occur naturally are titanium, zirconium and hafnium. The first three members of the group share similar properties; all three are hard refractory metals under standard conditions. However, the fourth element rutherfordium (Rf), has been synthesized in the laboratory; none of its isotopes have been found occurring in nature. All isotopes of rutherfordium are radioactive. So far, no experiments in a supercollider have been conducted to synthesize the next member of the group, either unpenthexium (Uph, element 156) or unpentoctium (Upo, element 158), and it is unlikely that they will be synthesized in the near future.

Group 5 element

Group 5 (by IUPAC style) is a group of elements in the periodic table. Group 5 contains vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). This group lies in the d-block of the periodic table. The group itself has not acquired a trivial name; it belongs to the broader grouping of the transition metals.

The lighter three Group 5 elements occur naturally and share similar properties; all three are hard refractory metals under standard conditions. The fourth element, dubnium, has been synthesized in laboratories, but it has not been found occurring in nature, with half-life of the most stable isotope, dubnium-268, being only 29 hours, and other isotopes even more radioactive. To date, no experiments in a supercollider have been conducted to synthesize the next member of the group, either unpentseptium (Ups) or unpentennium (Upe). As unpentseptium and unpentennium are both late period 8 elements it is unlikely that these elements will be synthesized in the near future.

IUPAC nomenclature of organic chemistry

In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry (informally called the Blue Book). Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry.

To avoid long and tedious names in normal communication, the official IUPAC naming recommendations are not always followed in practice, except when it is necessary to give an unambiguous and absolute definition to a compound. IUPAC names can sometimes be simpler than older names, as with ethanol, instead of ethyl alcohol. For relatively simple molecules they can be more easily understood than non-systematic names, which must be learnt or looked up. However, the common or trivial name is often substantially shorter and clearer, and so preferred. These non-systematic names are often derived from an original source of the compound. In addition, very long names may be less clear than structural formulae.


Lipoamide is a trivial name for 6,8-dithiooctanoic amide. It is the functional form of lipoic acid, i.e the carboxyl group is attached to protein via an amine with an amide linkage. Illustrative of the biochemical role of lipoamide is in the conversion of pyruvate to acetyl lipoamide.

Lipoamide itself is not naturally occurring.

Methylene (compound)

Methylene (systematically named methylidene, and dihydridocarbon), also called carbene is an organic compound with the chemical formula CH2 (also written [CH2]). It is a colourless gas that fluoresces in the mid-infrared range, and only persists in dilution, or as an adduct.

Methylene is the simplest carbene. It is usually detected only at very low pressures, very low temperatures, or as a short-lived intermediate in chemical reactions.


Mollicutes is a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin mollis (meaning "soft" or "pliable"), and cutis (meaning "skin"). Individuals are very small, typically only 0.2–0.3 μm (200-300 nm) in size and have a very small genome size. They vary in form, although most have sterols that make the cell membrane somewhat more rigid. Many are able to move about through gliding, but members of the genus Spiroplasma are helical and move by twisting. The best-known genus in the Mollicutes is Mycoplasma.

Mollicutes are parasites of various animals and plants, living on or in the host's cells. Many cause diseases in humans, attaching to cells in the respiratory or urogenital tracts, particularly species of Mycoplasma and Ureaplasma. Phytoplasma and Spiroplasma are plant pathogens associated with insect vectors.

Whereas formerly the trivial name "mycoplasma" has commonly denoted any member of the class Mollicutes, it now refers exclusively to a member of the genus Mycoplasma.


Paraquat (trivial name; ) or N,N′-dimethyl-4,4′-bipyridinium dichloride (systematic name) is an organic compound with the chemical formula [(C6H7N)2]Cl2. It is classified as a viologen, a family of redox-active heterocycles of similar structure. Paraquat was manufactured by Chevron. This salt is one of the most widely used herbicides. It is quick-acting and non-selective, killing green plant tissue on contact. It is also toxic to human beings and animals due to its redox activity, which produces superoxide anions. It has been linked to the development of Parkinson's disease and is banned in several countries.

Paraquat may be in the form of salt with chloride or other anions; quantities of the substance are sometimes expressed by cation mass alone (paraquat cation, paraquat ion).

The name is derived from the para positions of the quaternary nitrogens.

Periodic table forms
Sets of elements
See also

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.