What is aryl halide?

Answer 1

Members of the HalogensThere are six elements in Group 17 (old-style: VII or VIIA) of the Periodic Table: fluorine, chlorine, bromine, iodine, astatine and the as yet undiscovered ununseptium. The term halogen was coined to mean elements which produce salt in union with a metal. It comes from 18th century scientific French nomenclature based on erring adaptations of Greek roots.PropertiesThese elements are diatomic molecules (Fl2, Cl2, Br2 etc.) in their natural form. They require one more electron to fill their outer electron shells, and so have a tendency to form a singly-charged negative ion. This negative ion is referred to as a halide ion; salts containing these ions are known as halides.Halogens are highly reactive, and as such can be harmful or lethal to biological organisms in sufficient quantities. Fluorine is the most reactive element in existence, even attacking glass, and forming compounds with the heavier noble gases. It is a corrosive, highly toxic gas. Chlorine and iodine are both used as disinfectants for such things as drinking water, Swimming Pools, fresh wounds, dishes, and surfaces. They kill bacteria and other potentially harmful microorganisms, a process known as sterilization. Their reactive properties are also put to use in bleaching. Chlorine is the active ingredient of most fabric bleaches and is used in the production of most paper products.There are several trends that exist when moving down the group; increasing melting point, increasing boiling point, decreasing electronegativity and increasing reactivity.ReactionsHalide ions combined with single hydrogen atoms to form the hydrohalic acids (i.e., HF, HCl, HBr, HI), a series of particularly strong acids.UsesChlorine is by far the most abundant of the halogens, and the only one needed in relatively large amounts (as chloride ions) by humans. For example, chloride ions play a key role in brain function by mediating the action of the inhibitory transmitter GABA and are also used by the body to produce stomach acid. Iodine is needed in trace amounts for the production of thyroid hormones such as thyroxine. On the other hand, neither fluoride nor bromine are believed to be really essential for humans, although small amounts of fluoride can make tooth enamel resistant to decay.