Chemical Reactivity in Group 17 elements

Trends of chemical properties in group 17 elements

1. Oxidizing property of halogens

Group 17 elements are highly electronegative and hence they have strong tendency to accept electrons. Thus halogens act as strong oxidizing agents. F₂ is the strongest oxidizing halogen. A halogen can oxidizes halide ions of higher atomic number.

F₂ + 2X^- ----------> 2F^- + X₂

[X = chlorine (Cl), Bromine (Br) or Iodine (I)]


The oxidising ability of halogens decreases as we go down the Group.


2. Formation of Halides

Halogens combine with metals, nonmetals and even noble gases to form halides. Metal halides are ionic and their ionic character decreases as M-F > M-Cl > M-Br > M-I

Halogens combine with nonmetals and form covalent halides whose bond strength decreases as M-F > M-Cl > M-Br > M-I


3. Hydrides (Hydrogen halides)

Halogens combine with hydrogen to form covalent halides of the type HX and are regarded as hydrides. Their acidic and reducing character increase as we go down the group as HF < H-Cl < HBr < HI
The thermal stability decreases down the group HF > HCl > HBr > HI

Aqueous solution of hydrogen halides are known as hydrohalic acids.
Hydrogen chloride is prepared by heating sodium chloride with concentrated H₂SO₄.

2NaCl + H₂SO₄ ----------> Na₂SO₄ + 2HCl



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