Question

1.An element X belongs to third period and seventeenth group, state :
a) Name of the element.
b) The number of valence electrons in it.
c) The family to which it belongs. ​

Answer 1

Answer:

a) Chlorine(Cl)

b) 7 valence electrons

c) Halogen group

Explanation:

Group seventeenth groups are called halogen group because all the elements of this group are coloured.

Halogens are Fluorine(F), Chlorine(Cl), Bromine(Br), Iodine(I)

Chlorine is the third period element of this group and electronic distribution is 2,8,7

There is 7 elections in outermost shell(i.e. valence shell).Thus number of valence electron is 7.