Bromoethene vs Bromopropene

Question: Suggest an explanation for e unreactivity of Br in bromoethene as compared to 3-bromo-propene - passerby

My reply: Okay, firstly i would assume that you're asking about electrophilic addition for both reactions involving Bromine. Bromine as you know is an electrophile, which is also an electron withdrawing atom. Hence, Br in bromoethene will "spread" the electrons out from the electron rich C=C and stabilises bromoethene. In 3-bromopropene (i'm assuming it's 3-bromo-prop-1-ene), the Br atom is too far away from C=C and hence it does not really "spread" the electrons from the pi bond across the molecule. In this way, the C=C pi bond in 3-bromopropene will be more susceptible to a bromine attack compared to bromoethene.