Describe the 3 types of isomers?

Definition: Isomerism is when 2 molecules have the same molecular structure but a different structural arrangement (structural isomerism) or a different arrangement in space (stereoisomerism). 

Structural isomerism occurs when the structure of the molecules are different but they have the same overall chemical formula. This can be due to branching in a hydrocarbon chain. For example, if we have 2 molecules with formula C4H10,  we can have one structured as CH3CH2CH2CH3 and the other as CH3CH(CH3)CH3.

Stereoisomerism comes in two forms; geometric isomerism and optical isomerism. Both of these occur because of different arrangements of atoms in space. These are easier to visualise with diagrams.

Geometric isomerism (aka cis/trans or E/Z isomerism) occurs when there is a carbon-carbon double bond with a H and a different functional group on each carbon in the double bond. For example, a molecule that would show this kind of isomerism is CH3CH2CH=CHCH3. On the first carbon, we have a H and an ethyl group and on the second carbon we have a H and a methyl group. 

Optical isomerism is when we have a central carbon atom with 4 different functional groups attached, forming tetrahedral bonding from this carbon. These isomers are mirror images of each other and are called enantiomers and the central carbon is known as the asymmetrical carbon.

An example of a molcule that would form enantiomers is CH3CH2CH(OH)CH3. The asymmetrical carbon is underlined, and you can see that is an ethyl group (CH3CH2-), a H, and OH group and a methyl group attached (-CH3).

JC
Answered by Julia C. Chemistry tutor

31298 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

How would you find out whether a reaction is feasible?


How to answer the question: How does a bicarbonate buffer solution control pH when either an acid or a base is added?


i)Give the Correct full electronic configuration for the Mg2+ ion, ii) and state why it is easier to form the 2+ state for Mg than Ben


What is a dynamic equilibrium?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences