Isomerism Flashcards
What is structural isomerism?
Molecules which have the same molecular formula but different structural formula.
What are the three types of structural isomerism?
-Chain isomerism
-Positional isomerism
-Functional group isomerism
What is chain isomerism!
Molecules with the same molecular formula but a different arrangement of carbon atoms.
What is positional isomerism?
Molecules with the same molecular formula but which have the functional group in different positions in the molecules. e.g. butan-1-ol and butan-2-ol. Both have OH group but just on a different carbon.
What is functional group isomerism?
Molecules with the same molecular formula but different functional groups.
Functional groups include: OH groups of alcohol. NH2 group of amines. COOH group of carboxylic acids
What can show functional isomerism?
Cycloalkanes and alkenes.
What are stereoisomers?
Molecules with the same structural formula but a different arrangement of atoms in space.
Why do stereoisomers occur?
The C=C bond restricts rotation
Each C on C=C has two different groups.
Draw the Cis trans / EZ isomers for CHCl=CHCl
Cis isomer: Trans isomer:
Cl- -Cl Cl- -H
C=C C=C
H- -H H- -Cl
Draw the cis trans E/Z isomers for CHF=CHF
Cis isomer: Trans isomer:
H- -H H- -F
C=C C=C
F- -F F- -H
Draw the cis trans E/Z isomers for CFBr=CFBr
Cis isomer: Trans isomer:
F- -F. F- -Br
C=C. C=C
Br- -Br. Br- -F
What happens in Sp3 hybridisation for Methane? CH4. 1s2 2s2 2p2
-One s and 3p orbitals combine
-The s orbital moves up (increase energy)
-The 3 p orbitals all decrease in energy
-All orbitals have 1 electron in at the end
-Makes four single bonds.
-This makes 4 sp3 orbitals
-No double bonds because there are no electrons in the P orbital (top row)
What is the bond angle and molecular shape for Sp3 hybridisation?
109.5 degrees
Tetrahedral
What happens during sp2 hybridisation in Ethene C2H4.
-1s and 2p orbitals combine
-The s orbital moves up (increase energy)
-The 2 orbitals move down (decrease energy)
-All orbitals contain one electron
-This makes three sp2 hybrid orbitals
-there are 3 sigma bonds and 1pi bond because there was 1 spare P orbital
What happens during Sp hybridisation?
-1s and 1p orbital combine.
-This makes 2 sp hybrid orbitals so 2 sigma (single) bonds are formed.
-But there are 2 spare p orbitals on the top
row so this forms 2 Pi bonds.
-TRIPLE BOND IS FORMED
