(a) What is meant by a functional group? Explain with an example.
(b) Write three common functional groups present in organic compounds. Give their symbols/formulae.
(c) Name the functional groups present in the following compounds:
(i) CH3COOH (ii) CH3CH2CHO (iii) C2H5OH (iv) CH3COCH2CH3
(d) Name the functional group which always occurs in the middle of a carbon chain.
(e) Draw the structures for the following compounds:
(i) Ethanal (ii) Propanal (iii) Butanal (iv) Pentanal
(a) An ‘atom’ or ‘a group of atoms’ which makes a carbon compound (or organic compound) reactive and decides its properties (or functions) is called a functional group. The alcohol group, -OH, present in ethanol, C2H5OH, is an example of a functional group.
(b) (i) Halo group: -X
(ii) Alcohol group: -OH
(iii) Aldehyde group: -CHO
(c) (i) Carboxylic acid group
(ii) Aldehyde group
(iii) Alcohol group
(iv) Ketone group
(d) Ketone group, -CO-
(e) (i) Ethanal
\(H-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{O}{\overset{||}{C}}-H\)
(ii) Propanal
\(H-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{O}{\overset{||}{C}}-H\)
(iii) Butanal
\(H-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{O}{\overset{||}{C}}-H\)
(iv) Pentanal
\(H-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{H}{\overset{|}{\underset{H}{\underset{|}{C}}}}-\overset{O}{\overset{||}{C}}-H\)