prefix

(noun)

One or more letters or syllables added to the beginning of a word to modify its meaning; for example, kilo can be added to gram to create kilogram

Related Terms

Examples of prefix in the following topics:

  • SI Unit Prefixes

    • The basic SI units can be expressed as fractions and multiples of basic units by using a set of simple prefixes.
    • Briefly review the basic SI units before you study the prefixes.
    • There are 20 accepted prefixes.
    • Keep in mind that prefixes should never be combined.
    • The prefixes redefine the measurement as either a multiple or a fraction of the basic unit.

  • Naming Molecular Compounds

    • Molecular compounds are named using a systematic approach of prefixes to indicate the number of each element present in the compound.
    • When naming molecular compounds prefixes are used to dictate the number of a given element present in the compound. " mono-" indicates one, "di-" indicates two, "tri-" is three, "tetra-" is four, "penta-" is five, and "hexa-" is six, "hepta-" is seven, "octo-" is eight, "nona-" is nine, and "deca" is ten.
    • If there is only one of the first element, you can drop the prefix.
    • If there are two vowels in a row that sound the same once the prefix is added (they "conflict"), the extra vowel on the end of the prefix is removed.

  • Naming Hydrates

    • The name of a hydrate follows a set pattern: the name of the ionic compound followed by a numerical prefix and the suffix -hydrate.
    • The name of a hydrate follows a set pattern: the name of the ionic compound followed by a numerical prefix and the suffix "-hydrate."
    • The prefixes are the same Greek prefixes used in naming molecular compounds.
    • The Greek prefixes used in naming hydrates for numbers 1/2 through 10 are as follows:

  • Naming Alkenes and Alkynes

    • Substituents are added to the name as prefixes to the longest chain.
    • Rotation is restricted around the double bond, so prefixes can be added to differentiate stereoisomers.
    • If the compound is cyclic, this information is noted by adding the "cyclo-" prefix.

  • Naming Acids and Bases

    • As acids, these compounds are named starting with the prefix "hydro-," then adding the first syllable of the anion, then the suffix "-ic."
    • When you have a polyatomic ion with one more oxygen than the "-ate" ion, then your acid will have the prefix "per-" and the suffix "-ic."
    • With two fewer oxygen than the "-ate" ion, the prefix will be "hypo-" and the suffix will be "-ous."

  • Benzen Derivatives

    • A few mono-substituted compounds are named by using a group name as a prefix to "benzene", as shown by the combined names listed below.
    • In the case of disubstituted benzenes, the prefixes ortho, meta & para are commonly used to indicate a 1,2- or 1,3- or 1,4- relationship respectively.
    • Some disubstituted toluenes have singular names (e.g. xylene, cresol & toluidine) and their isomers are normally designated by the ortho, meta or para prefix.

  • SI Units of Pressure

    • Since the quantities measured can have such a wide range, a standardized prefix system has been set in place.
    • Pressure can be represented by many different units and prefixes.
    • A prefix may be added to a unit's name to describe a multiple of the original unit.

  • Nomenclature of Alkene Stereoisomers

    • Configurational stereoisomers of the kind shown above need an additional nomenclature prefix added to the IUPAC name, in order to specify the spatial orientations of the groups attached to the double bond.
    • Thus far, the prefixes cis- and trans- have served to distinguish stereoisomers; however, it is not always clear which isomer should be called cis and which trans.
    • Assignment of a cis or trans prefix to any of these isomers can only be done in an arbitrary manner, so a more rigorous method is needed.
    • In order to assign a configurational prefix the priority order of substituents at each double bond carbon must be determined.

  • Nomenclature

    • An easy to remember, but limited, nomenclature system makes use of an elemental prefix for the heteroatom followed by the appropriate carbocyclic name.
    • A short list of some common prefixes is given in the following table, priority order increasing from right to left.
    • It makes use of the same hetero atom prefix defined above (dropping the final "a"), followed by a suffix designating ring size and saturation.
    • Systems having a lesser degree of unsaturation require an appropriate prefix, such as "dihydro"or "tetrahydro".
    • Note that when a maximally unsaturated ring includes a saturated atom, its location may be designated by a "#H " prefix to avoid ambiguity, as in pyran and pyrrole above and several examples below.

  • Alkanes

    • Alkanes are named with the suffix "-ane" following the hydrocarbon prefixes.
    • For carbon chains with length of 6, 7, 8, 9, and 10 atoms, the prefixes are "hex-," "hept-," "oct-," "non-," and "dec-," respectively.
    • The prefix "n-," for normal, is reserved for the linear, unbranched forms of these alkanes .