Give reasons: (i) The elements of group 18 are called zero valent. (ii) Group 17 elements form uninegative anions.
Answer – (i) Group 18 elements have their outermost shells completely filled and the atoms of these elements have no tendency to gain or lose electrons. Thus, the elements of this group are zero valent and almost unreactive.
(ii) Group 17 elements have 7 valence electrons, one electron less than the maximum number of electrons that can be accommodated in the outermost shell. Therefore, it is easier for these elements to gain an electron and form uni-negative anions, so as to attain noble gas configuration.