Unit 14 Assignment C
Understand types, structures, reactions, uses and properties of isomers
The summary chart above shows the five different types of isomerism.
For each type of isomerism, you will build models and draw the displayed structural
formulae of the compounds.
You will describe the difference in chemical or physical properties between the
isomers.
Provide appropriate references for your sources of information and use correct
scientific terminology.
What is an isomer?
Isomers are molecules that have the same molecular formula, but have different arrangement of
the atoms in space. That excludes any different arrangements which are simply due to the molecule
rotating as a whole or rotating about particular bonds. For example, both of the following are the
same molecule. They are not isomers. Both are butane. There are also endless other possible ways
that this molecule could twist itself. There is completely free rotation around all carbon-carbon
single bonds.
What are structural isomers?
Structural isomers are compounds with the same molecular formula but different structural
formulae. They can occur with all functional groups. There are three types of structural isomer:
chain, positional and functional group.
,Part 1
1. Chain isomerism- have differences in chain length. Examples include:
Butane and methyl propane
Make models of the 2 chain isomers of the compound with molecular formula C 4H10.
Give the structural formulae of the two isomers.
Isomer A- butane Isomer A – butane
(structural formula) (photograph of 3-D model)
Isomer B –2- methyl propane Isomer B –2- methyl propane
(structural formula) (photograph of 3-D model)
, The boiling point of the linear isomer, butane, is higher than the boiling point of the
branched isomer, 2-methyl-propane.
Explain this fact with reference to the intermolecular forces between the molecules.
The straight chain isomers have the most extended structure and larger surface area
in comparison to branched chain isomers, which have compact structure. Thus, the
intermolecular forces are weaker in branched chain isomers. Hence, they have lower
boiling point compared to straight chain isomers and they need more energy to break
these weak forces. The boiling point of butane is -0.5 oC and the boiling point of 2-
methylpropane is -12oC this shows that it has lower boiling point.
Make models of the chain isomers of a larger alkane. Name each isomer and give its
structural formulae.
Name of Isomer C: Isomer C - pentane
(structural formula) (photograph of 3-D model)
Name of Isomer D: Isomer D 2-methyl- butane
(structural formula) (photograph of 3-D model)
Understand types, structures, reactions, uses and properties of isomers
The summary chart above shows the five different types of isomerism.
For each type of isomerism, you will build models and draw the displayed structural
formulae of the compounds.
You will describe the difference in chemical or physical properties between the
isomers.
Provide appropriate references for your sources of information and use correct
scientific terminology.
What is an isomer?
Isomers are molecules that have the same molecular formula, but have different arrangement of
the atoms in space. That excludes any different arrangements which are simply due to the molecule
rotating as a whole or rotating about particular bonds. For example, both of the following are the
same molecule. They are not isomers. Both are butane. There are also endless other possible ways
that this molecule could twist itself. There is completely free rotation around all carbon-carbon
single bonds.
What are structural isomers?
Structural isomers are compounds with the same molecular formula but different structural
formulae. They can occur with all functional groups. There are three types of structural isomer:
chain, positional and functional group.
,Part 1
1. Chain isomerism- have differences in chain length. Examples include:
Butane and methyl propane
Make models of the 2 chain isomers of the compound with molecular formula C 4H10.
Give the structural formulae of the two isomers.
Isomer A- butane Isomer A – butane
(structural formula) (photograph of 3-D model)
Isomer B –2- methyl propane Isomer B –2- methyl propane
(structural formula) (photograph of 3-D model)
, The boiling point of the linear isomer, butane, is higher than the boiling point of the
branched isomer, 2-methyl-propane.
Explain this fact with reference to the intermolecular forces between the molecules.
The straight chain isomers have the most extended structure and larger surface area
in comparison to branched chain isomers, which have compact structure. Thus, the
intermolecular forces are weaker in branched chain isomers. Hence, they have lower
boiling point compared to straight chain isomers and they need more energy to break
these weak forces. The boiling point of butane is -0.5 oC and the boiling point of 2-
methylpropane is -12oC this shows that it has lower boiling point.
Make models of the chain isomers of a larger alkane. Name each isomer and give its
structural formulae.
Name of Isomer C: Isomer C - pentane
(structural formula) (photograph of 3-D model)
Name of Isomer D: Isomer D 2-methyl- butane
(structural formula) (photograph of 3-D model)
