Question

Explain why elements in group 1 and 7 of the periodic table have same valency?

Answer 1

Answer:

The valency of an element is determined by the number of valence electron in the outermost shell of an atom of an element. (2) All the elements in a group have the same number of valence electrons. Therefore, elements in the same group should have the same valemcy

Answer 2

Answer:

Group 1 loses 1 electron from outer most shell and become +1 ion, Group 7 of the periodic table gains 1 electron and form -1 valency. Both groups gain or tend to gain electronic configuration of nobel gases. That's why group 1 and 7 have the same va