Molecules are not static. Single bonds can rotate causing the shape of a molecule to change. This is known as changing the conformation of a molecule. Some conformations are more favourable than others, these are sometimes called conformers. Other conformations are disfavoured. They are the barrier to rotation or a transition state between conformers. This summary looks at the conformations of simple alkanes.

The classic, what kind of isomer do I have here flowchart. There are a number of these online but it is useful. Surprisingly, hard to fit onto one page (nicely).

The name of a molecule must describe its structure including any elements of stereochemistry. This post introduces stereochemical descriptors for alkenes and simple stereocentres. Although I no longer teach this at undergraduate level, it should be useful for those that do. I’ve also thrown in some tips on manipulating drawings containing stereochemistry.

The shape of molecules is vital to understanding their chemistry and properties. The simple geometry of each atom is only half the picture, and you must also consider stereoisomers. These are compounds that have all the same atoms and bonds yet are different due to their shape. Students often find this a daunting topic. This introduction just lays out the basics. Sometime in the future, I’ll go into more detail (as I do teach a postgraduate course on this topic!)