Determining cis, z, trans, or e [ENDORSED]

[Nathan Sanchez 1F]

Is cis always Z and is trans always E? If not, why?

[Jenny2G]

Cis means same side which is the same as Z while trans means the opposite side which means E. So cis is always Z and trans is always E.

[Chem_Mod]

Cis means same side which is the same as Z while trans means the opposite side which means E. So cis is always Z and trans is always E.

Incorrect.

[Vincent Tse 2B]

The E/Z naming system is used particularly for naming alkenes, determined by identifying the priority group bonded to the carbons: if the priority groups are on the same side, it is Z; if opposite, it is E.

Cis and trans refer to conformations and the direction of substituents in either axial or equatorial bonds. If the substituents point in the same direction (e.g. axial down and equatorial down) then it is cis. Note, that the type of bond does not matter, only the direction. If the substituents point in opposition (e.g. axial up and axial down), then it is trans.