Bond Lengths and Angles -Pi overlap brings carbon atoms closer. -Bond angle with pi orbital increases. ·Angle C=C-His121.7°；Angle H-C-His116.6 -Cis and trans isomers cannot be interconverted -No rotation around the carbon-carbon 1.33 116.6° H ethylene ethaneBond Lengths and Angles Pi overlap brings carbon atoms closer. Bond angle with pi orbital increases.  Angle C=C-H is 121.7° ;Angle H-C-H is 116. 6° Cis and trans isomers cannot be interconverted. No rotation around the carbon—carbon