Question

Halogens are meta directing or para directing group

Answer 1

: Halogens are group seventeen elements lying just left to the noble gases in the periodic table. Halogens include five elements which are fluorine (F), chlorine (Cl), bromide (Br), iodine (I), and astatine (At).

Complete step by step answer:
Halogens include five toxic, non-metallic, electronegative elements.
Since halogens are electronegative elements, it’s electronegativity causes them to be electron withdrawing groups.
An electron withdrawing group takes away electron/s from the central atom.
An atom or a group of atoms that donate carbon easily to a carbocation ( ${{C}^{+}}$) will be an ortho-, para- directing group.
Usually, the meta product is favoured in electron withdrawing groups (EWG) because they form secondary carbocation at meta position but halogens are an exception they are electron withdrawing though they are electron withdrawing groups.
Halogens are weakly deactivating.
Hence, due to electronegativity and electron withdrawing ability halogens withdraw electrons via inductive effect.
Due to polarization of sigma bonds inductive effect takes place.
Resonance is caused due to interaction between a lone pair and pi bond or two pi bonds of adjacent atoms.
Inductive effect is more important than resonance.
Now due to resonance, the carbocation forms at ortho and para positions due to which it is easy for atoms to join at ortho para positions.
Therefore, halogens are para directing.

Note: The para product is slightly more common than ortho product due to steric hindrance. (Due to steric bulk it poses a hindrance or it slows down the chemical reaction known as steric hindrance).