Position of halogens in periodic table

1.Chlorine is placed second after fluorine in group VIIA.

2. Other members of this group are fluorine, bromine, iodine and astatine (the last member is radioactive).

3. Members of this group are called 'halogens' meaning salt producers.

4. Atoms of halogens have seven electrons in their valence shell, thus show -1 valency.

5. Halogens may be solid, liquid or gas.

Halogen	Fluorine	Chlorine	Bromine	Iodine
State	Gas	Gas	Liquid	Solid
Colour	Yellow	Greenish yellow	Reddish brown	Deep purple

6. The color of halogens becomes darker as we move down the group from fluorine to iodine.

7. The reactivity of halogens decreases as we move down the group. Fluorine is the most reactive element of this group.

8. Halogen acids

All the members of the group VII A form binary haloacids.

Examples:

HF - Hydrofluoric acid

HCl - Hydrochloric acid

HBr - Hydrobromic acid

HI - Hydroiodic acid

9. Oxy-acids

All the members of the group VII A also form oxy-acids.

Examples:

HClO - Hypochloric acid

HClO₂ - Chlorus acid

HClO₃ - Chloric acid

HClO₄ - Perchloric acid

10. All the members of the group VII A are strong oxidising agents since they have a strong tendency to accept one electron in order to attain an octet.