122 Unsaturated hydrocarbons(不饱和烃) contain multiple bonds saturated hydrocarbon Unsaturated hydrocarbon CH3-CH2-CH2-CH3 CH3 CH=CH--CH3 n-butane 2-butene12.2 Unsaturated hydrocarbons (不饱和烃) contain multiple bonds CH3 CH CH CH3 2-butene saturated hydrocarbon Unsaturated hydrocarbon CH3－CH2－ CH2 － CH3 n-butane