Question

An element belongs to 3rd period and 17th group of periodic table find its size with comparison to its neighbouring elements?

Answer 1

Since element X' belongs to 3rd period, it means that the element X has three valence electrons. Also, it belongs to group 17 which means that it has 7 valence electrons as Valence electrons = 17 - 10 = 7 So, the electronic configuration of the element X is 2, 8, 7

 (1) Since the outermost shell has 7 electrons in its outermost shell means that it requires one more electron to acquire noble gas configuration. So, the valency of X is 1.