CHEMISTRY 3.5 ANSWERSWORKSHEET TWO ORGANIC Isomerism1. Isomers have the same molecular formula but different structural formula.2. pentane CH3CH2CH2CH2CH3 2-methylbutane CH3CH(CH3)CH2CH3 2,2-dimethylpropane (dimethylpropane) CH3 C(CH3)2CH33. but-1-ene CH2CHCH2CH3 but-2-ene CH3CHCHCH3 2-methylpropene CH2C(CH3)CH34. propanal CH3CH2CHO propanone CH3COCH35. (a) The molecule will have a chiral carbon atom, ie a carbon atom with four different groups on it. (b) Two enantiomers have identical chemical properties, but in biochemical systems they behave differently. They also have the same physical properties except for their effect on plane-polarised light. One enantiomer will rotate the plane of polarisation clockwise and the other anticlockwise. (c) Many biological molecules such as amino acids are optically active. Often only one of the isomers is able to function properly in living things.6. (a) (b) CH2 CH3 CH3CH2 CH3CH2 H2C CH CH CH3 C C CH3 CH3 H Cl Cl H7. (a) NH2CH2CH2CH2CH(CH3)COOH (b) CH3CHClCH2CHClCH2CH3 (c) CH3CHO (d) CH3CH2CHBrCH3 (e) (CH3)2CHCH(CH3)COOH (f) Any of the above arranged as in answer 6(a) above.