prefix

Physics

(noun)

That which is prefixed; especially one or more letters or syllables added to the beginning of a word to modify its meaning; as, pre- in prefix, con- in conjure.

Chemistry

(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:

  • Prefixes and Other Systems of Units

    • SI prefixes precede a basic unit of measure to indicate a multiple or fraction of the unit.
    • A metric prefix, or SI prefix, is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit.
    • Each prefix has a unique symbol that is prepended to the unit symbol.
    • Because multiple prefixes may not be used, in the case of the kilogram the prefix names are used with the unit name "gram" and the prefix symbols are used with the unit symbol "g. " With this exception, any SI prefix may be used with any SI unit, including the degree Celsius and its symbol °C.
    • Apply prefixes to units and distinguish between SI and customary units

  • 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:

  • Understanding Medical Terms

    • This systematic approach to word building and term comprehension is based on the concept of: (1) word roots, (2) prefixes, and (3) suffixes.
    • The prefix can be added in front of the term to modify the word root by giving additional information about the location of an organ, the number of parts, or time involved.
    • Prefixes do not normally require further modification to be added to a word root because the prefix normally ends in a vowel or vowel sound, although in some cases they may assimilate slightly and an in- may change to im- or syn- to sym-.
    • One approach involves breaking down the word by evaluating the meaning of the suffix first, then prefix, and finally the word root.

  • 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.