Structural isomerism in the alkanes
2 marks · EasyExplain why it is not possible to convert one structural isomer of pentane directly into another simply by rotating bonds.
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Because structural isomers have different connections between their atoms. Changing from one to another requires breaking and forming covalent bonds, not just rotating them.
Also accept: Bonds must be broken and new ones made to change from one isomer to another
Common mistakes: Think they can be changed by simple rotation; Confuses with stereoisomerism
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Marking points
M1 · 1 mark · States that isomers have different atom connectivity or bonding
A1 · 1 mark · Explains that changing from one isomer to another needs bond breaking and forming
Worked solution
Structural isomers have their atoms joined up differently. To change from one to the other, you must break and remake bonds, not just rotate parts of the molecule.