Isomerism
Isomerism is when organic compounds consist of the same number of atoms of each element, but
they are arranged differently. So, in other words, an isomer is a version of an organic compound
which has the same molecular formula but a different displayed /3D formula.
There are types and subtypes of isomerism that can occur. The types are structural and stereo:
Structural Isomers are when the same atoms exist within the compound, but they are
connected differently. This isomerism is caused by the movement of an R group (chemical
species).
Stereoisomers are when the same atoms exist within the compound, but they have a
different spatial arrangement. This isomerism is caused by the rotation of the bonds so that
specific atoms occupy a different position within 3-dimensional space.
The subtypes of structural isomers are chain, positional and functional:
Chain isomerism is when the carbon chain bonds are rearranged to form a different structure. A
chain isomer has similar chemical properties but can slightly differ in their physical properties. Chain
isomers can result in more/less branching.
Two examples of chain isomerism:
Butane and 2-methylpropane both have the molecular formula, C 4 H 10 but butane has a
carbon chain of 4 carbons while 2-methylpropane has a carbon chain of 3 carbons with the
4th bonded to the main carbon chain at the 2 nd position as a methyl group.
Butane’s structural and 3D formulae:
2-methylpropane's structural and 3D formulae:
, Difference of chemical properties Difference of physical properties
2-methylpropane is less reactive. The 2-methylpropane has a lower boiling
hyper conjugated resonance structure point. The more branching, the lower
of butane involves a primary the boiling point because branching
carbocation while the hyper conjugated weakens the intermolecular forces that
resonance structure of 2- exist between linear carbons and
methylpropane involves a more stable decreases the surface area.
secondary carbocation. 2-methylpropane is slightly more
soluble in water. The more branching,
the higher the solubility of the
molecule because of the decreased
surface area.
2-methylpropane has a lower density.
The more branching, the lower the
density.
Pentane and 2-methylbutane both have the molecular formula, C 5 H 12 but pentane has a
carbon chain of 5 carbons while 2-methylbutnane has a carbon chain of 4 carbons with the
5th carbon bonded at the 2nd position of the main chain as a methyl group.
Pentane’s structural and 3D formulae:
2-methylbutane's structural and 3D formulae:
Difference of chemical properties Difference of physical properties
2-methylbutane is less reactive. 2-methylbutane has a lower boiling
point.
2-methylbutane is slightly more soluble
in water.
2-methylbutane has a lower density.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller DelilahDevi. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.64. You're not tied to anything after your purchase.