In discussing stereochemistry, we will learn more different types of isomers. To clarify the concepts, it is a good idea to have a summary of the isomers in organic chemistry. There are two major types of isomers: constitutional isomers and stereoisomers. We had detailed discussions of constitutional isomers in Chapter 2 and will focus on stereoisomers in this chapter. Stereoisomers are molecules with the same bonding, but groups are in different spatial arrangements. At beginning of this chapter, we will learn more about geometric isomers in alkenes and the E/Z naming system. Then, we will move on to a brand-new category of stereoisomers – isomers with a chirality center. The flowchart here (Fig. 5.1a) shows the correlations and differences between different types of isomers (pay attention to the definitions included) and provides a useful guideline.