What is the reactivity trend of halides?

1 Answer


Halogens increase in reactivity from the bottom to the top of their Group.


Fluorine is the most reactive of the halogens. It is also the smallest of the halogens.

Fluorine has the highest electronegativity. Electronegativity is a measure of the attraction an atom has for the electrons in a shared bond.

Halogens have an electron structure of #s^2 p^5#.

To reach the stable structure of the noble gases (#s^2 p^6#), the halogens need only one more valence electron. The halogens react by gaining that electron.

The smaller the atom, the easier it is for the protons in the nucleus to attract another electron.

The larger the atom, the further the valence electrons are from the nucleus. This means that the nucleus in a large atom has less attraction for the valence electrons.

So, the larger the atom, the less reactive the halogen is, and the smaller the atom, the more reactive the halogen is.