Q. Study of Elements of group 16?

We shall discuss Group 16 elements, viz., oxygen, sulphur, selenium, tellurium and polonium. These elements are called chalcogens or the ore forming elements. This name was derived from the Greek name for copper, since most of the copper ores contain members of this group. Compared to Groups 14 and 15 elements, the elements of this group are even more non- metallic in their behaviour. These also exhibit a gradual change towards metallic characteristics down the group. Thus polonium, the last member of the group, is almost metallic. We will describe the occurrence and extraction of these elements and also their allotropic modifications. Uses of these elements and some of their compounds will also be described. We shall then go on to discuss the-general behaviour of these elements and their important compounds like hydrides. Halides oxides and oxoacids.