So, we were talking about R and S-carvone, but what do R and S stand for? We also have D and L, and we also plus and minus. Why are there all these different letters?
Steven - There are simply different systems that have come about for naming them. So, for example, the D and the L, they refer to the way in which certain substances rotate the plane of polarisation of polarised light. So, D is dextrorotatory, L is levorotatory, so right and left. That's one of them. Another of them is another set of arbitrary rules for the order in which bonds are substituted.
Harriet - Thanks and the R is recto and S is sinister, I think.