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 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 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 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 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 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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