Structural isomers Flashcards
What are structural isomers?
Molecules that have the same molecular formula but different structural formula (different structural arrangement of atoms)
3 types of structural isomers
Chain
Positional
Functional group
Chain isomers
Where the carbon chain can be arranged differently, by having branches in different places or being linear
How similar are the chemical properties of chain isomers?
Similar because they contain the same functional group
How similar are the physical properties of chain isomers
Different because they have differences in branching, which affects the points of contact between molecules thus weakens intermolecular forces. This can heavily effect physical properties
What doesn’t count as a chain isomer?
When the ‘branch’ is on the last carbon because then it’s not a branch
Since the carbon chain is still the same length
Positional isomers
Where the carbon chain/skeleton is the same but the functional group is attached to a different carbon
How similar are the chemical properties of positional isomers?
Different
How similar are the physical properties of positional isomers?
Different
What is important about positional isomers?
That the functional group is attached to A DIFFERENT CARBON ATOM
And not just the same one at a different angle
Functional group isomers
Molecules which have the same molecular formula but the atoms are arranged into different functional groups
How similar are the chemical properties of functional group isomers?
Very different because they contain different functional groups thus undergo different mechanisms
How similar are the physical properties of functional group isomers?
Very different because they contain different functional groups thus form different types of intermolecular forces
So varying amounts of energy required to melt/boil
How can we know if molecules are actually isomers or just the same but looks different?
By naming the molecule using nomenclature
If the name is different = an isomer
