Families halogens

Chlorine, a member of the halogen family, is a greenish yellow gas having a pungent odor at ambient temperatures and pressures and a density 2.5 times that of air. In Hquid form it is clear amber SoHd chlorine forms pale yellow crystals. The principal properties of chlorine are presented in Table 15 additional details are available (77—79). The temperature dependence of the density of gaseous (Fig. 31) and Hquid (Fig. 32) chlorine, and vapor pressure (Fig. 33) are illustrated. Enthalpy pressure data can be found in ref. 78. The vapor pressure P can be calculated in the temperature (T) range of 172—417 K from the Martin-Shin-Kapoor equation (80) ... 

Iodine [7553-56-2] I, atomic number 53, atomic weight 126.9044, is a nonmetaUic element belonging to the halogen family in Group 17 (VIIA) of the Periodic Table. The only stable isotope has a mass number of 127. There are 22 other iodine isotopes having masses between 117 and 139 14 of these isotopes yield significant radiation. 

Recall that, because of the strong H-F bond, hydrofluoric acid is a weak acid with a small acid dissociation constant Ka of 6.8 x 10-4. In contrast, the other binary acids of the halogen family—HC1, HBr, and HI—are strong acids that completely dissociate in water.) The fluorosilicic acid produced, H2SiF6, is a water-soluble substance with a structure as in Fig. 6.3.1. 

Moving down halogen family, shielding effect and greater distance from nucleus would cause easier polarization of electron cloud. 

Elemental fluorine, which is a member of the halogen family, is a pale yellow-green, irritating gas with a sharp odour and atomic mass of 18.998. Fluorine is chemically most reactive of all the elements and does not therefore occur naturally in the free state. In combination it comprises 0.065% of the earth s crust, being the 13th element in abundance [1], and is an inevitable part of the biosphere and human life. The term fluorine is, in this report, used to denote the element in any of its forms and fluoride to denote free inorganic fluoride to which a fluoride ion-selective electrode (ISE) responds. 

The halogen family, fluorine, chlorine, bromine, and iodine has only recently been introduced into atmospheric chemistry.9 The catalytic cycle, with an atom such as Cl in the presence of its monoxide CIO, can... 

This section summarizes the chemical and physical properties which are shared in some degree by all of the nonmetallic elements, and the following sections briefly delineate the chemistry of several additional nonmetallic elements—carbon, silicon, nitrogen, phosphorus, and sulfur. A later section discusses the properties of the elements of the halogen family. 

All the elements of the halogen family except astatine occur in nature in the form of their compounds. Because of their marked chemical activity, they are never found in nature in the uncombined state. 

A review of the means whereby the elements of the halogen family may be prepared either in the laboratory or on an industrial scale provides further insight into the interrelationships of these elements. 

Chlorine is by far the most useful of the elements of the halogen family. This fact becomes evident when one learns that the annual production of chlorine in the United States alone amounts to approximately 250,000 tons. Much of this chlorine is used in the bleaching of fabrics, wood pulp, and so forth. Considerable quantities of this element are used in treating water supplies for the purpose of destroying harmful bacteria. Many of the poisonous gases used in the world wars were chlorine compounds, such as mustard gas [(C1C2H4)2S], chloropicrin... 

Each member of the halogen family combines with hydrogen to form a compound of the type HX, where X represents a halogen. 

In 1940, Corson, Mackenzie, and Segre announced the production of an isotope of element 85, astatine (At), which is the last member of the halogen family. This synthesis involved bombardment of bismuth with alpha particles in a cyclotron ... 

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