Going from fluorine to chlorine to bromine and then to iodine, the electronegativity:

1. These are halogens going down Group 17. 2. Down a group, atomic size increases and the nucleus holds bonding electrons less tightly. 3. Hence electronegativity decreases from fluorine to iodine. _Source: RRB Group D CEN-02/2018 PYQ, Q.18._