Probably the most important generalization that can be made about the halogen elements is that they are all oxidizing agents i.e., they raise the oxidation state, or oxidation number, of other elements-a property that used to be equated with combination with oxygen but that is now interpreted in terms of transfer of electrons from one atom to another. Ionic bond: sodium chloride, or table salt Fluorine is the most reactive of the halogens and, in fact, of all elements, and it has certain other properties that set it apart from the other halogens. There is, however, a progressive change in properties from fluorine through chlorine, bromine, and iodine to astatine-the difference between two successive elements being most pronounced with fluorine and chlorine.
The halogen elements show great resemblances to one another in their general chemical behaviour and in the properties of their compounds with other elements. Astatine and tennessine do not occur in nature, because they consist of only short-lived radioactive isotopes. The percentages of the halogens in the igneous rocks of Earth’s crust are 0.06 fluorine, 0.031 chlorine, 0.00016 bromine, and 0.00003 iodine. In combined form, fluorine is the most abundant of the halogens in Earth’s crust. They were given the name halogen, from the Greek roots hal- (“salt”) and - gen (“to produce”), because they all produce sodium salts of similar properties, of which sodium chloride-table salt, or halite-is best known.īecause of their great reactivity, the free halogen elements are not found in nature.
The halogen elements are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). Halogen, any of the six nonmetallic elements that constitute Group 17 (Group VIIa) of the periodic table.
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