Nomenclature | Chemistry | CSEC CXC lessons online – Study Guide

The Functional Group

The Functional Group is the atom or group of atoms in a compound whose reactions determine the chemical properties of the compound, i.e ‘how the compound behaves.’

Eg. Propanoic acid and butanoic acid have similar chemical properties because they contain the same functional group. 

Propanoic acid – ( C2H5COOH)            Butanoic acid – (C3H7COOH) they both contain the COOH group. 

 

 

Naming Organic Compounds - Nomenclature

 

When naming organic compounds the first thing one must do is identify the longest carbon chain in the compound.

This is the number of carbon atoms that form a continuous chain ( the chain could be straight or bent)

The number of carbon atoms in the main chain determines the first part of the name.

  • with 1 carbon atom- the name of the compound starts with meth
  • with 2 carbon atom- the name of the compound starts with eth
  • with 3 carbon atoms- the name of the compound starts with prop

The second part of the name is determined by the functional group

eg. (ane – if it’s an alkane)

 

Assign numbers to the carbon atoms in the main chain so that the branches attached to the main chain would attain the lowest possible number.

The name of the branch is determined by the number of carbon atoms in the branch

eg. if the branch is CH3 the name of the branch is methyl (one carbon atom)

Methyl is an alkyl which is of the general formula CNH2N + 1