Cis-trans isomerism Also referred to as geometric isomers, these compounds have different configurations due to the inflexible structure of the molecule. (wikipedia.org)
Two requirements must be met for a molecule to present cis-trans isomerism: 1. (wikipedia.org)
A simple, but not always accurate test whether a molecule is achiral or not is the presence of a mirror plane (equal to a plane of reflection or plane of symmetry , symmetry element s ) in the structure of a molecule. (tu-darmstadt.de)
The ultimate criterion for chirality ( handedness ) of a molecule is the non-superimposability of a structure with its mirror image geometry through pure translation and/or rotation only. (tu-darmstadt.de)
Compounds1
Compounds possessing mirror symmetry are always optically inactive, such as, for example, cis - and trans -1,4-disubstituted cyclohexane derivatives, or symmetrically cis -1,2-disubstituted cyclohexanes (see also the 3D structures at 'Cycloalkanes' ). (tu-darmstadt.de)
Optical2
This property, the only physical property in which the two types of tartrate salts differed, is due to optical isomerism. (wikipedia.org)
whereas the non-superimposability of a structure with its mirror image results in chirality ( optical activity , see below). (tu-darmstadt.de)