Chem 4:4 - Nomenclature and Isomerism Flashcards
What are structural isomers?
Structures with the same molecular formula but different structural arrangements of atoms
What are the 3 types of structural isomers?
Chain isomers
Positional isomers
Functional Group Isomers
What are chain isomers ?
Different arrangement of the carbon skeleton,
some straight chains and some branched chains
What are positional isomers?
Same skeletons and atoms but FG in different place
What is a functional group isomer?
Same atoms arranged into different functional groups
What is steroisomerism?
Same structural formula but a different arrangement of atoms in space
In terms of rotation around bonds, how do single and double bonds work?
There is rotation around a single bond but no rotation round a double bond
What does this no rotation round a double bond mean?
This means that some alkene are steroisomers
When does stereoisomerism occur in an alkene
When the carbon atoms in the double bond hand 2 different groups attatched.
What do you get with stereoisomerism in alkenes
an E and Z isomer
What is optical isomerism?
A type of stereoisomerism
A chiral carbon has 4 different groups attatched to it
It is possible to make 2 different molecules around this carbon to make OPTICAL ISOMERS or ENANTIOMERS.
What shape will an optical isomer be?
Tetrahedral
In terms of light,, what do optical isomers do ?
Rotate the plane of polarised light
What do the positive and negative isomers do to the light
And what does normal light do ?
+ve isomer rotates it in the clockwise direction
-ve isomers rotate light in the anticlockwise direction
Normal light vibrates it in all directions
What is a racemate or racemic mixture ?
Contains equal quantities of each enantiomer of an optically active compound
What don’t racemantes show and why
They don’t show optical activity bc they cancel eachothers light rotating affect
What do chemists usually do in terms of a-chiral molecules
React them together because there will be an equal chance of forming the enantiomers.
