Trends in group 7
Flourine is the most electronegative and the electronegativity decreases down the group.
Their boiling points increase down the group as the IMF's between molecules (Van der Waals) increase as the atoms get bigger, as their are more electrons in the shells.
They become less reactive as you move down the group, therefore halogens higher up the group will displace halides from lower down.
Their reducing power increases down the group, as the outer electrons are further away (and also experience more shielding) from the nucleus so are easier to donate.
Reactions of halide…