Generally the trans isomer is more stable than the corresponding cis isomers. This is because in the cis isomer, the bulky groups are on the same side of the double bond. The steric repulsion ofthe groups makes the cis isomers less stable than the trans isomers in which  bulky groups are on the opposite side.

Propene does not exhibit geometrical isomerism.
All alkenes with identical substrate do not show geometrical isomerism. Geometrical isomerism is possible only when each double bonded C atom is attached to two different atoms or groups. Eg. In propene no geometrical isomers are possible because one of the double bonded carbon has two identical H atoms.

The cis-isomer can be converted to trans isomer or vice versa is only if either isomer is heated to a high temperature or absorbs light. The heat supplies the energy (about 62kcal/mole) to break the \(\pi \) bond so that rotation about o bond becomes possible, Upon cooling, the reformation of the 1t bond can take place in two ways giving a mixture both cis and trans forms of trans- 2-butene and cis- 2-butane.

The isomers which have same bond connectivity but different arrangement of groups or atoms in space are known as stereo isomers. This branch of chemistry dealing with the study of three-dimensional nature (spactial arrangement) of molecules is known as stereo chemistry. The metabolic activities in living organisms, natural synthesis and drug synthesis 1 involve various stereoisomers.

(i) Lewis structure or dot structure,
(ii) Dash structure or line bond structure,
(iii) Condensed structure
(iv) Bond line structure