Isomerism Flashcards
two compounds can have the same molecular formula but different……, making them………..
structural formulae, making them structural isomers
the two types of structural isomerism are
chain isomerism and position isomerism
chain isomerism refers to molecules with
different carbon chains
butane and methylpropane are examples of what kind of isomerism
chain isomerism
butane and methylpropane are chain isomers because
their carbon chains are different
position isomerism refers to molecules with
the same functional group attached in different positions on the same carbon chain
propan-1-ol and propan-2-ol are examples of what kind of isomerism
position isomerism
true or false: two molecules can be both chain and position isomers?
true
in organic chemistry, we use ‘stereo’ to mean
the different ways to arrange atoms or groups of atoms
stereoisomers have the same….. and same……. but different……..
molecular formula and structural formula, but different arrangements
when showing stereoisomers, we have to (specific way of drawing bonds)
draw the bonds at 120 degree angles around the carbon atoms in question, having two groups of atoms or atoms bonded on each carbon of the double C=C
by drawing the bonds at 120 degree angles in stereoisomers, we can see……and…….notation
trans- (opposite) and cis- (same side)
trans means
the same groups of atoms or single atoms are on opposite sides of the C=C bond and opposite sides of the molecule
cis means
the same groups of atoms or single atoms are still on opposite side of the C=C bond, but on the same side of the molecule
compounds which require cis- and trans- to name them are called
geometric isomers
geometric isomerism is a kind of
stereoisomerism
geometric isomerism exists in…..but not……
alkenes but not alkanes
geometric isomerism cannot occur in alkanes as
there is no double bond which stops groups attached to the double C=C bond from rotating
what causes geometric isomerism?
the double C=C bond in alkenes prevent groups attached to the carbons in the double C=C from rotating, so restricted rotation is created
the three steps for E-Z notation are
1) Use the part of the name that can be used for both isomers using normal nomenclature
2) Use priority rules to decide which of the two atoms or groups of atoms on each side will be used to compare with the other side. Use the atomic number of the atoms to decide, the highest atomic number is used
3) Now decide whether the highest priority atoms are on the same side (Z) or opposite (E) sides of the molecule
