metalloid element in 7th (viia) race of the period is always called halogen which consists of five elements, fluorine, chlorine, bromine, iodine and astatine. the halogen element, as a representative and the liveliest metalloid, mostly exists in form of halogenated in nature (iodine in forms of iodated & astatine is a radioelement).
damage of halogen
the organic halide can cause cancer in the body of human, and its low degradation leads to hazardous accumulation in the biogeocenose. some volatile organic halides destroys the ozonosphere seriously, and causes grate effect on the environment and human being’s health, therefore some halide is defined as a chemical which is harmful to human beings and environment, and is forbidden or limited in use. at present, the halogen exists and is being applied in each field in form of various compound. and though thw special laws and regulations on halogen have not yet been issued around the world, many non-governmental environmental protection organizations worldwide is driving halogen-free act actively.
application of halogen
most organic halide is man-made product, and some kinds of commodity --hydrocarbons are more than 15000. because of some outstanding functions, such as flame-retardant, easy-dissolvable, high reactivity, they are widely used in every field, for example, retardant, refrigerants, menstruum, raw material of organic chemical industry, pesticide, bleaching, degreaser of wool etc.
