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Isolation and storage is the winning task of Noble Prize Isolation and storage is the winning task of Noble Prize Elemental (pure) fluorine is the most reactive substance known to man. It is difficult to isolate and store pure fluorine such that almost anything placed in the path of a stream of fluorine gas will spontaneously burst into flame at ordinary temperature.Henry Moissan is the man who first celebrated the isolation of fluorine with less expensive copper equipment coated with copper fluoride. He also constructed especially corrosion‐resistant containers crafted from a mixture of platinum and iridium with fluorite stoppers.In 1906, two months before his death, Moissan received the Nobel Prize in chemistry for his fluorine isolation as well as the invention of the electric arc furnace.

Learning Objectives

After completing the topic, the student will be able to:

  • List the elements present in group 17(VIIA) or halogen family in periodic table.
  • Write the electronic configurations of group 17(VIIA) elements.
  • Discuss the details of occurrence and abundance of halogens.
  • Give the preparation methods of halogens.
  • Discuss the physical and chemical properties of halogens.
  • Examine the anomalous behavior of fluorine and give the reasons for its peculiarity.
  • Compare the nature of fluorine and oxygen.
  • Describe the general properties of compounds of halogens.
  • Identify the structures of oxyacids of chlorine and bromine.
  • Give the important uses of halogens.
Halogens Halogens The elements of group VII of the periodic table are called halogens, which means "salt formers".
Group 17 elements - Halogens

Gases form very important components of many chemical reactions. In the periodic table of elements gases are mainly found in Group 17 and Group 18. The Group 17 gases are known as halogen gases and the Group 18 or zero group gases are known as the noble gases. Let us discuss the chemical properties of Group 17 in detail. The halogen family in the Group 17 of the modern periodic table has elements Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and Astatine (At). Mnemonic: First Class Bakery In Austria.

Halogens exist in the elemental form as diatomic molecules. At room temperature fluorine and chlorine exist as ‘gas’ bromine is liquid and Iodine is a solid. The final member of the group, namely astatine, is intensely radioactive. Its most stable isotope has a half‐life of only 8.3 hours. Fluorine is the most electronegative element found in nature ‐ it loves to attract an electron and fill its shell.

Halogen elements are found in salts present in sea water Halogen elements are found in salts present in sea water There are three different halogens found in seawater. They are chlorine, bromine, and iodine. The other halogen elements are fluorine and astatine. Halogens are very reactive and are found in many minerals as well as seawater.
Salts of Halogens

The term ‘halogen’ is derived from Greek origin hals (sea) and halos(salt). It means ‘salt producing’ since these elements are found in the salts present in seawater. The natural salt that we obtain from evaporation of seawater, is known as common salt or table salt. It is predominantly sodium chloride. It has small amounts of other chlorides and iodides (such as NaI, MgI2, MgCl2 etc.).

Iodized salt is a modern day commercially available salt‐which is NaCl mixed with NaI. Iodine is necessary, in trace amounts, for our thyroid glands to function properly; it regulates our growth and body temperature. Chlorine gas is used as a disinfectant and bleaching agent. In swimming pools mild chloric acid HOCl is mixed in water ‐ the nascent oxygen released is useful for killing bacteria in the water. This is the reason why swimming pools always smell of chlorine.