Can we go over why halogens are ortho, para-directing but a deactivating group again? (F is so electronegative that it overrides even the resonance donating effect of its lone electron pairs. For Cl, Br, and I, the lone electron pairs are taking too much space, which makes their overlap with the pi-system of the benzene ring less efficient, so the donating resonance effect is outcompeted by the inductive withdrawing effect. Also, empty d-orbitals of Cl, Br, and I account for additional resonance withdrawing effect. -GS).