Halogen Group Elements – importance
Halogen group or Group 17 of the periodic table consists of five elements which play a significant role in our daily lives as fluorine is used in toothpaste or chlorine is used as a disinfectant to clean the water.
The five members of Group 17 are:
These elements are collectively known as halogens. The word halogen has been derived from a Greek descent in which ‘halo’ means salt and ‘genes’ mean born. Therefore, halogens in Greek mean salt producers. Astatine is placed in the halogen group since its behaviour is similar to that of iodine although it is a radioactive element.
The below table lists the properties of halogen group elements.
|Melting point||−219.62 °C||−101.5 °C||−7.3 °C||113.7 °C||302 °C|
|Boiling point||−188.12 °C||−34.04 °C||58.8 °C||184.3 °C||337 °C|
|Density||0.0017 g/cm3||0.0032 g/cm3||3.1028 g/cm3||4.933 g/cm3||6.2–6.5 g/cm3|
Fluorine is a chemical element which is represented with a symbol F and has an atomic number 9. It takes the first position in group 17 of the periodic table. In the year, 1530 fluorine was discovered by Georgius Agricola. It is abundantly found in the earth’s crust. Fluorine is mainly found in cryolite (Na3AlF6), fluorspar(CaF2) and fluorapatite (3Ca3(PO4)2.CaF2) deposits. For commercial purposes, fluorspar is the most common source fluorine.
Chlorine is a chemical element which is represented with the symbol Cl and has an atomic number 17. It is abundantly found in the lithosphere. It is never found in the free state due to its strong chemical affinity except in rare cases. It is a minor constituent of products from volcanic eruptions. The most common minerals containing chlorides are rock salt (NaCl), sylvite (KCl) and carnallite (MgCl2.KCl.6H2O).
Bromine is a chemical element which is represented with symbol Br and has an atomic number 35. It takes the twenty-fifth position in an order of abundance in nature. It is always found as a halide with other elements due to its high chemical reactivity. Bromine is majorly produced by the United States, Germany, and Israel. Ocean water is a primary natural source of this halogen.
Iodine is a chemical element which is represented with the symbol I and has an atomic number 53. It is found in nature as iodides or iodates. Iodine is usually found in rocks, underground brines and soil. Seawater is also a source of iodine.
Astatine is a radioactive chemical element which is represented with the symbol At and has an atomic number 85. It occupies the last position of the halogen group. It derives its name from Greek which means unstable. It is a very rarely found element and at any given time the concentration of this component is less than one gram in the earth’s crust. However, this element can be produced by bombarding bismuth-209 with an alpha particle.
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