Cis isomer : Two identical atoms or groups in double bond Those on the same side are cis isomers, also represented by cis -. Trans isomer The trans isomers of two identical atoms or groups on both sides of the double bond are also expressed by trans. ⑴ The molecule cannot rotate freely (otherwise it will become another molecule)
⑵ double bond The same carbon cannot have the same Group ； Note: Isomerism The molecular formula is the same, Structural Different, Cis trans isomerism It is the different spatial conformation. But cis trans isomerism belongs to isomerism. If two carbon atoms on the double bond are connected with four completely different atoms or groups, press“ Sequential rule ”Compare two atoms or groups connected to each carbon atom, if two Better group stay pi bond The homolateral plane isomer is Z-type isomer, and the heterolateral plane isomer is E-type isomer. Properties of cis trans isomers
Cis trans isomer, atomic or Atomic cluster The connection order and double bond position of are the same, but the spatial arrangement is different. Therefore, the chemical properties are basically the same, but biological activity Different, there are some differences in physical properties: generally, trans has a higher melting point, a lower solubility, and is relatively stable. 
