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In describing chemical substances, we are dealing with a need for effective communication using as appropriate language. In a sense chemical nomenclature is as much a language as is Greek or Mandarin, albeit a restricted one with a very specific purpose; it has an organizational structure. "rules of grammar", conventions and undergoes continuous evolution.

Chemical nomenclature may be considered to be a language. As such, it is made up of words, and it should obey the rules of syntax. Generally, nomenclature systems use a base on which the name is constructed. This base can be derived from a parent compound name in substitutive nomenclature or from a central atom name such as cobalt in additive nomenclature.

Define Nomenclature

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Definition of Nomenclature:

The name of a chemical compound usually contains information about its molecular composition. The naming of things or choosing the names of compounds especially in science or chemistry called nomenclature of chemical compounds.

Binomial Nomenclature Definition


Binomial nomenclature is the scientific method of giving names to all the organisms so that they can be easily distinguished from one another. It is the system of nomenclature using two terms, the first one indicating the genus and the second the species.

Binomial nomenclature examples are the mango tree is scientifically known as Mangnifera indica.

Nomenclature Rules

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How to name chemical compounds?

The rules for naming the chemical compound is also based on the type of the compound. A set of rules given below to name a chemical compound.
  1. Name the first element using the exact element name.
  2. Name the second element by writing the stem name of the element with the suffix -ide.
  3. Add prefixes to each element name to denote the subscript of the element in the formula. Generally the prefix mono is used only on the second element in the binary compound to distinguish from other examples containing multiple atoms.
  4. For metals that can have more than one stable charge, report the charge as part of the name. Write the charge in roman numeral form in parentheses immediately after the metals name.

Chemical Nomenclature Chart

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The word nomenclature simply means naming. There are many times when having names for chemicals is more convenient than having their formulas. Chemical naming falls into two main groups: that for ionic compounds formed of positive and negative ions, and that for non ionic compounds.

S.No
Group nomenclature
Formula
Nomenclature
Ester nomenclature  RCOOR
  1. The name for the alkyl part of the ester appears first and is followed by a separate word giving the name for the acyl part of the ester.
  2. The name for the alkyl part is simply the name of the R group present.
  3. The name of the alkyl part of the ester is obtained by dropping the -ie acid ending for the acid's name and adding the suffix -ate.
2
Fatty acid nomenclature  CH3(CH2)nCOOH
  1. Each has a common or trival name, which has been used for many years.
  2. A systematic way which is more recent and has the advantage of describing the structure of the fatty acid to which it belongs.
  3. The omega system which classifies fatty acids according to the position of the first double bond, counting from the methyl end of the molecule.
3
Ether nomenclature  R-O-R 
  1. Select the longest carbon chain and use its name as the base name.
  2. Change the -yl ending of the other hydrocarbon group to -oxy to obtain the alkoxy group name; methyl becomes methoxy, ethyl becomes ethoxy etc.
  3. Place the alkoxy name, with a locater number, in front of the base. 
4
Amine nomenclature  R-NH2, R-NH-R', R'-NR-R"
  1. Select the parent chain the longest chain to which the nitrogen atom is attached.
  2. Name the parent chain by changing the -e ending of the corresponding alkane name to -amine.
  3. Number the parent chain from the end nearest the nitrogen atom.
  4. the position of attachment of the nitrogen atom is indicated by a number in front of the parent chain name.
  5. The identity and location of any substituents are appended to the front of the parent chain name. 
5
Carboxylic acid nomenclature 
CnH2n+1COOH
The IUPAC nomenclature of carboxylic acid have ac -oic acid suffix. In common nomenclature the suffix is usually -ic acid. For example, stearic acid and octadecanoic acid.
Alcohol nomenclature CnH2n+1OH
Alcohol nomenclature follow these steps.
  1. Identify the parent chain.
  2. Number the parent chain.
  3. Name the substituents and place them alphabetically in front of the parent chain.
  4. Assign stereo chemistry if applicable. 
7
Benzene nomenclature C6H6 
  1. Benzene derivatives are named by adding the name of substituent as prefix to the benzene ring.
  2. Some derivatives possess common or trivial names.
8
Enzyme nomenclature ES (E = enzyme, S = substrate)
  1. Enzyme nomenclature is based on the reaction an enzyme catalyzes. The suffix "-ase" identifies an enzyme.
  2. The IUB established a commission on enzyme nomenclature to systematize, categorize and catalog enzymes. 
9
Aldehyde nomenclature RCHO The IUPAC system aldehydes are named by replacing "e" from the corresponding name of alkane by suffix "al". Therefore aldehydes are called alkanals. 
10
Ketone nomenclature R-CO-R The name of the ketone is obtained by replacing "e" of the parent alkane by "one". The positions of the carbonyl group and substituents are indicated by numbers.
11
Amide nomenclature RC(O)NHR'
  1. The ending of the name of the carboxylic acid is changed from -ic acid or -oic acid to -amide. For example, benzoic acid becomes benzamide.
  2. The names of groups attached to the nitrogen are appended to the front of the base name, using an N- prefix as a locator. 
12 Oxyanions AxOyz (A = chemical element and O = oxygen) Oxyanions are named with -its or -ate, for a leaser or greater quantity of oxygen.

Alkane Nomenclature

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The alkanes are considered to be parent compounds by chemists as they are used to produce a huge variety of organic chemicals. Moreover, the naming of different organic compounds is based on alkane nomenclature.

The IUPAC rules for naming alkanes are as follows.
  1. Choose the longest carbon chain and name this.
  2. Name all groups which are attached to the longest chain as alkyl groups.
  3. Number the longest carbon chain beginning at the end that is closest to an alkyl group.
  4. Write the name of the alkane by naming all the substituent first in alphabetical order, followed by alkane name for the longest carbon chain in the compound.


Naming Cycloalkanes


The IUPAC rules for naming cycloalkanes are as follows.

  1. The name of an unsubstituted cycloalkane is obtained by attaching the prefix cyclo- to the name of the corresponding normal alkane having the same number of carbon atoms as in the ring.
  2. Substituents on the ring are named and numbers indicate their positions. The ring is numbered so that the carbons bearing the substituents will have the lowest numbers.


Naming Branched Alkanes


The key to naming branched alkanes is knowing the name of the branch or branches that are attached to the main carbon chain. These branches are formally called substituents. A substituent is an atom or group of atoms attached to a chain of carbon atoms. For branched chain alkanes, the substituents are specifically called alkyl groups.

Alkene Nomenclature

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The following steps are followed for the nomenclature of simple alkenes.
  1. Determine the longest continuous carbon chain that contains the double bond, and name it with the appropriate root and the suffix -ene.
  2. Assign the first carbon atom of the double bond the lowest possible number.
  3. Name substituent branches as alkyl groups with their positions indicated by numbers.
  4. Indicate multiple substituents with the appropriate Greek prefix.

Alkyne Nomenclature

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The rules for naming alkynes are identical to those used to name alkenes except the ending -yne is used instead of -ene. The steps are given below..
  1. Locate the parent chain.
  2. Number the chain to give the alkyne the lowest possible number.
  3. Name the substituents.
  4. Place the substituents in alphabetical order in front of the parent name.

Inorganic Nomenclature

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Systematic procedures have been agreed upon for naming inorganic compounds based on their molecular and structural formulas. It is essential to translate quickly between the name and the structural formula.

Naming inorganic compounds is usually quite straightforward because small numbers of atoms are involved. Inorganic compounds are classified into four categories in order to simplify the nomenclature.
  1. Ionic compounds
  2. Molecular compounds
  3. Acids and bases
  4. Hydrates


Naming Hydrates


Hydrates are ionic compounds that have absorbed water. They are named as the ionic compound followed by a numerical prefix and -hydrate. For example, CuSO4.5H2O is named as copper (II) sulfate pentahydrate.

Nomenclature Practice

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The existing nomenclature system was established by International Union of Pure and Applied Chemistry (IUPAC). Chemistry nomenclature practice problems are given below.

Solved Examples

Question 1: Assign both common and IUPAC names for the following amide compounds.

 Amide Compounds
Solution:
 
  1. The parent acid for this amide is butyric acid (common) or butanoic acid (IUPAC). The common name for this amide is butyramide and the IUPAC name is butanamide.
  2. In both the common and IUPAC system of nomenclature the name of the parent acid is the same benzoic acid. The name of the amide is N,N-diphenylbenzamide.

 

Question 2: Find the IUPAC name for the following benzene derivatives.
  1. Benzene Compound
  2. Compounds of Benzene

Solution:
 
  1. This is something we draw on board. Thia is the hood ornament of a Mercedes, so this is Mercedes Benzene.
  2. The highest priority functional group is the alcohol. The longest chain contain the OH is nine, so it is a nonenol of some sort. Numbering from the right to give the OH the lower number gives us 1-methoxy-5-phenylnon-8-en-2-ol.