Question | Answer |
What are stereoisomers? | Molecules with the same structural formula but a different arrangement in space |
Why are alkenes able to form stereoisomers but alkanes cannot? | There's a lack of rotation around the C=C double bond and so can form stereoisomers |
How do you differentiate between an E-isomer and a Z-isomer? |
Each of the groups linked to the double-bonded carbons is given a priority. If the two carbon atoms have their 'higher priority groups' on opposite sides, then it's an E-isomer. If they're on the same side, then it's a Z-isomer
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According to the Cahn-Ingold-Prelog priority rules, how is the highest priority group on each of the C=C carbons determined? | The highest priority group is the one which has the atom with the highest atomic number directly bonded to the carbon atom |
Is this molecule an E-isomer or a Z-isomer?
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Z-isomer The higher priority groups are on the same side |
How would you determine the higher priority group when the atoms directly bonded to the carbon are the same? | You look at the next atom along in each group |
Is this molecule an E-isomer or a Z-isomer?
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E-isomer On the left, the atoms directly bonded to the carbon are the same, but the next atom along the top group is higher than the next atom along on the bottom group. |
Complete the sentences: Cis-trans isomerism is a special type of E/Z isomerism where the two carbon atoms either side of the __________ bond have at least ______ group(s) in common. You can't use the cis-trans system if there are more than _____ different groups (other than ____________ atoms) attached around the double bond because you can't tell which isomer is which. | Cis-trans isomerism is a special type of E/Z isomerism where the two carbon atoms either side of the DOUBLE bond have at least ONE group in common. You can't use the cis-trans system if there are more than TWO different groups (other than HYDROGEN atoms) attached around the double bond because you can't tell which isomer is which. |
What is the difference between a cis- and a trans-isomer | The cis-isomer has the two identical groups on the same side of the C=C double bond. The trans-isomer has the two identical groups on opposite sides of the C=C double bond. |
Is this a cis- or a trans-isomer?
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Cis-isomer The groups that the carbon atoms have in common (H) are on the same side |
Is this a cis- or a trans-isomer?
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Trans-isomer The groups that the carbon atoms have in common (H) are on opposite sides |
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