question_answer 19)

               The position of three elements A, B and C in the periodic table are shown below : Group 16                             Group 17                 -                                              -                 -                                              A                 -                                              -                              B                                             C (a) State whether A is metal or non-metal. (b) State whether C is more reactive or less reactive than A. (c) Will C be largeror smaller in size than B ? (d) Which type of ion, cation or anion will be formed by the element A ? 

Answer:

(a)Group 17 represents halogen family. All the elements included in the family are non-metals. Therefore, element A is a non-metal.                            (b) Reactivity of non-metals is generally due to the electron accepting tendency of their atoms. Down the group, the atomic size increases. Therefore, the attraction of the nucleus for the outside electrons decreases. This means that down the group of non-metals,  reactivity decreases. Thus, the element C is less reactive than the element A.              (c) Atomic size of the elements decreases along a period. The elements B and C are present in the same period. Since C is placed after B, the size of the element C is less than that of B. (d) The elements A, as pointed out earlier is a non-metal which belongs to group 17. It has seven valence electrons (2, 8, 7). In order to have the configuration of the nearest noble gas element, it will take up one electron and change to anion i.e., A- ion.