Consider the following sets of problems:

enter image description here

I was hoping someone could clarify what each checkbox means exactly. All of these answers are incorrect (except the first one with the check marks signifies the correct answers).

For example, why are the first pair different molecules? What makes something a conformation/constitution/structural isomer?

What does it mean to say something is an "identical conformation of the same molecule" vs "different conformation of the same molecule?"

When can I definitiviely tell if something is an enantiomer or just a diastereomer? It seems like (for an enantiomer) you can't just do the check of "switch all dashes to wedges and all wedges to dashes" because, as in the third pair of newman projections, they are enantiomers of each other but I don't understand why that is.

  • 1
    $\begingroup$ This isn't an answer as I can't summarize it, but this site is really useful for that: Isomers explained via metaphor with cats. masterorganicchemistry.com/2010/11/11/… $\endgroup$
    – Canageek
    Nov 29, 2013 at 3:31
  • $\begingroup$ Which book is this ?? $\endgroup$ Feb 19, 2016 at 18:45
  • $\begingroup$ Can you mention the right answers to the questions in the picture? $\endgroup$
    – user28867
    Apr 13, 2016 at 4:53

1 Answer 1


I'm going to assume that you don't need an explanation for the checkboxes the same molecule and difference molecules, so that leaves the following:

The terms constitutional isomers and stereoisomers make up two broad categories of isomers (molecules with the same chemical formula). Constitutional isomers typically have different connectivities and stereoisomers have the same connectivities but differ in spatial arrangements.

enantiomers are stereoisomers that are non-superimposeable mirror images of one another. Your hands are (roughly) enantiomers. both are optically active is true of enantiomers.

diastereomers also known as geometric isomers are also stereoisomers that are not mirror images of one another. cis- and trans-dichloroethene are diastereomers.

If you do a web image search of isomer flowchart you'll see a lot of informative information on isomers. Linked below is the public domain version from Wikipedia which is an example (although not the best in my opinion.)

enter image description here


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.