Halogens-Position in periodic table

The elements placed in group 7 (VIIA) of the periodic table are called halogens or salt producers. All these elements form salts called halides, e.g. NaCl, NaI, KCl, KI etc. Halogen is an ancient Greek word meaning 'salt producer'. Halogens have seven electrons in their valence shell and so are monovalent.

Element	Atomic number	Electronic configuration	Valency	State	Colour
Fluorine	9	2, 7	-1	Gas	Greenish but more yellow
Chlorine	17	2, 8, 7	-1	Gas	Greenish yellow
Bromine	35	2, 8, 18, 7	-1	Liquid	Dark red liquid
Iodine	53	2, 8, 18, 18, 7	-1	Solid	Dark purple
Astatine	85	2, 8, 18, 32, 18, 7	-1	-	-

Remember

Bromine is the only Liquid non-metal. Iodine when heated undergoes sublimation. 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.