Prefixes Greek numerical

Stoichiometric Proportions. The stoichiometric proportions of the constituents in a formula may be denoted by Greek numerical prefixes mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- (Latin), deca-, undeca- (Latin), dodeca-,. . . , icosa- (20), henicosa- (21),. . . , tri-conta-(30), tetraconta-(40),. . . , hecta-(100), and so on, preceding without a hyphen the names of the elements to which they refer. The prefix mono can usually be omitted occasionally hemi-(1/2) and sesqui- (%) are used. No elisions are made when using numerical prefixes except in the case of icosa- when the letter i is elided in docosa- and tricosa-. Beyond 10, prefixes may be replaced by Arabic numerals. 

Names.—The names of the different hydrocarbons are similar and are in harmony with the idea of an homologous series. The common termination ane is given to all and, above the fourth member, a Greek numerical prefix indicates the number of carbon atoms in the molecule. The five-carbon compound is pent-ane, the six carbon hex-ane, etc. The first four members have special non-numerical prefixes as methane, eth-ane, prop-ane and but-ane. Similarly the radicals of each hydrocarbon simply take the termination yl in place of ane, thus, but-yl, pent-yl, hex-yl, etc. 

Covalent compounds have Greek numerical prefixes (see Table 2.6) to indicate the number of atoms of each element in the compound. The first word has a prefix only when more than one atom of the element is present the second word usually has a numerical prefix. 

Replacement of oxygen by sulfur is denoted by thio-, with a Greek numeral prefix except that, with mono-substituted acids, mono is usually not expressed (e.g., H2S2O3, thiosulfuric add H2CS3, tritkiocarbonic. add). 

So-called solvates containing molecules of H2O, H2O2, and NHj are called hydrates, peroxyhydrates, and ammoniates, respectively, in accordance with the I.U.C. rules. The number of such molec iles present is indicated by Arabic figimes rather than Greek numerical prefixes (both methods are given in the I.TJ.C. rules) e.g., gal-lium III) perchlorate 6-hydrate (rather than hexahydrate). 

Since the I.U.C. rules and the Chemical Abstracts indexes do not provide any assistance in naming carbonyls and nitrosyls, the names used in the literature, in which Greek numerical prefixes are used, have been retained e.g.,... 

The numbers of ligands are indicated by Greek numerical prefixes (di, tri, tetra, penta, hexa, etc.). Where these would create ambiguity, multiplicative prefixes (bis, tris, tetiakis, pentakis, hexakis, etc.) and brackets are used, e.g. bis(methylamine). 

Proportions of the various parts are expressed by Greek numerical prefixes but there are extremely important qualifications that mono (for unity) is usually omitted and that other numerical prefixes may also be omitted if no ambiguity results. Multiplicative numerical prefixes (bis, tris, tetrakis, etc,) are used when followed directly by another numerical prefix and may be used whenever ambiguity might otherwise be caused and prefixes may be delimited by parentheses to aid clarity further (examples are on pp. 28, 29). The terminal a of tetra, penta, etc., has normally been elided in English before another vowel in inorganic chemistry, but this is now expressly forbidden by the lUPAC 1965 revision. 

Many of the other workers in this field call these complexes methinyltricobalt enneacarbonyls. However, we are not Greek scholars and prefer the more prosaic Latin numerical prefixes. 

By now you have noticed that names of alkanes end in -ane. Also, alkanes with five or more carbons in a chain have names that use a prefix derived from the Greek or Latin word for the number of carbons in each chain. For example, pentane, has five carbons just as a pentagon has five sides, and octane has eight carbons just as an octopus has eight tentacles. Because methane, ethane, propane, and butane were named before alkane structures were known, their names do not have numerical prefixes. Table 22-1 shows the names and structures of the first ten alkanes. Notice the underlined prefix representing the number of carbon atoms in the molecule. 

When, as frequently happens, two elements unite with each other to form more thsin one compound, these are usually distinguished from each other by prefixing to the name of the element varying in amount the Greek numeral corresponding to the number of atoms of that element, as compared with a fixed number of atoms of the other element. 

As nuclear is a Latin word, it should properly have Latin numerical prefixes. However, the use of Greek prefixes is well established in this context (contrast multinuclear NMR). lUPAC also use Greek prefixes with dentate ( didentate , etc ). 

Incidentally, valent (valency) is of Latin origin, and so should be used with Latin numerical prefixes— univalent, bivalent, tervalent (or trivalent), quadrivalent, quinquevalent, sexivalent, not the Greek mono-, di-, tetra-, penta-, or hexa-. 

Modified Forms in Common Use. There are numerous situations in which the foregoing system does not meet all requirements. In the formation uf binary compounds, several elements exhibit more Ilian two states of oxidation. One method, recommended by the IUPAC, of handling these situations is the use of prefixes derived from Greek to indicate stoichiometric composition, e.g., titanium dichloride, TiCL and dinitrogen oxide (nitrous oxide) N 0. Other accepted methods ofindicating proportions of constituents are the Stock system (oxidation number) and the Ewens-Bassett (charge number) system. 

The prefix multipliers are given in Table 1.2. It is crucial that you learn all the multipliers, as well as their numerical meanings and abbreviations. Notice some abbreviations are capital letters, while others are lower case letters. It is important that you not confuse these. The letter m is particularly overused as an abbreviation. Notice that the abbreviation for micro is the Greek letter mu (p), which is equivalent to the English letter m. 

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