1. The problem statement, all variables and given/known data I just had my textbook tell me ethylene is a planar molecule. Not wanting to regurgigate crammed information, I'm trying to understand why the molecule has to be planar. Why can't two hydrogen atons located on one side be oriented in a perpendicular way to the two other hydrogen atoms located on the other side? I don't see why this model wouldn't be more stable. 2. Relevant equations Theory of orbitals.