Mono- prefix

Note that the absence of a prefix from the first named element in a molecular compound implies that there s only one atom of that element. In other words, the prefix mono- is unnecessary for the first element only. You still have to attach a mono- prefix, when appropriate, to the names of subsequent elements. 

A. Dinitrogen monoxide, sulfur hexafluoride, and dichlorine octoxide. Notice that none of these compounds contain any metals, which means that they re most certainly molecular compounds. The first compound contains two nitrogen atoms and one oxygen atom, so it s called dinitrogen monoxide. The second compound contains one sulfur and six fluorines. Because sulfur is the first named element, you don t need to include a mono- prefix. You simply name the compound sulfur hexafluoride (rather than monosulfur hexafluoride ). Using the same methods, the third compound is named dichlorine octoxide. 

The mono- prefix is usually not used unless it is important to distinguish between compounds of the same two elements. 

There are exceptions to using the prefixes shown in Table 8.3. The first element in the compound name never uses the mono- prefix. For example, CO is carbon monoxide, not monocarbon monoxide. Also, if using a prefix results in two consecutive vowels, one of the vowels is usually dropped to avoid an awkward pronunciation. For example, notice that the oxygen atom in CO is called monoxide, not monooxide. 

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. 

Step 2 Add Greek prefixes to indicate the number of atoms of each element. Mono- is usually omitted. 

These examples show that when information is not needed to identify the compound, it is omitted from the name. In the first name, for instance, it is not necessary to tell how many sodium ions are present, because we can deduce the number from the name of the complex anion. In the second name, the oxidation state of zinc is omitted because it is always +2. In the fourth name, the single bromo ligand is not preceded by the prefix mono. 

Using the same logic, the chemical compound H20 can also be named using the prefixes mono- and di-. Because there is only one oxygen atom in water and the oxygen is the second element in the compound, the prefix mono- is used. The scientific name for H20 is dihydrogen monoxide. Of course, this compound is also much better known by its common name—water. 

The final o or a may be dropped if the name of the element begins with a vowel. The prefix mono is being used less often, so you may only see it in a very small number of compounds such as carbon monoxide, CO. 

Carbon monoxide is one of the very few cases where the prefix mono is used. In general, you should not use mono in any other compound. 

Figure 12.15 Gangliosides. The prefix mono-, di, tri- or tetra- denotes the number of sialic acid W-acetyl neuraminic acid, NANA) residues present in the molecule. The many different gangliosides have complex structures and for convenience shorthand notations are used. The two commonest were introduced by Svennerholm, who named the parent compound GM1, and Wiegnandt, who named it Ggnti. The latter system gives enough information for the structures to be worked out from the shorthand form once the symbols have been learnt. GalNAc represents N-acetyl galactosamine in the above structure.

Graft copolymers with known numbers of graft chains are named using numeric prefixes (mono, bis, tris, etc). 

In the other method, the ending -ane is changed to -ene or -yne to indicate the presence of a double or triple bond. This is used for alkanes and mono- and polycyclic alkane parent hydrides. In alkanes and cycloalkanes, the change of the -ane ending to -ene or -yne indicates the presence of one double or triple bond. Multiplicative prefixes di-, tri-, tetra-, etc. are used to signal the multiplicity of unsaturated bonds. Locants placed immediately in front of the endings -ene and -yne are used as needed. 

Using Table 6-2, translate the subscripts into prefixes. Omit the prefix mono- on the first named element in a compound where applicable. 

Molecular Formula A method of representing a molecule by a written formula, listing which atoms and how many of them are in the molecule, without showing how they are bonded to each odier. Monitor The measurement of the environmental factors which may adversely affect health. "Mono-" The prefix that means one. 

GUIDELINE 2 When two or more compounds have different numbers of the same elements, prefixes are added to remove the ambiguity. The first four prefixes are mono- ( one ), di- ( two ), tri- ( three ), and tetra- ( four ). The prefix mono-, however, is commonly omitted from the beginning of the first word of the name ... 

Saccharide Another term for carbohydrate. The prefixes mono-, di-, and poly- are used before this term to indicate the length of the carbohydrate. 

The prefix mono- is always omitted unless its presence is necessary to avoid confusion. 

Name of an element or elementary substance of definite motneutar formula or strut ture. These are named by adding the appropriate numerical prefix [see above] to the name of the atom to designate the number of atoms in the molecule. The prefix mono is not used except when the element does not normally exist in a monoatonuc state. 

Use of nmftlpBcative prefixes. The proportions of the constituents, be they mono-atomic or polyatomic, may be indicated by numerical prefixes (mono-, di-. tri-. lelra-, penta-. etc.) as detailed in [Table 1-3]. These precede the names they modify. Joined... 

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