Hi, this is a sterechemistry problem. If you have a fisher projection problem with Ch3 at the top, Cl on the left, ethyl group on the right, and a CH double bonded to a CH2 (CH=CH2)on the bottom, it is an S nomenclature correct?

I figured out that Cl is 1st priority, and CH3 is 4th priority....but can you explain to me why the ethyl group is of higher priority than the CH=CH2?