Question

(a) What is the usual number of valence electrons and valency of group 18 elements of the periodic table?
(b) What happens to the number of valence electrons in the atoms of elements as we go down in a group of the periodic table?

Answer 1

◾ There is no valence electron in group 18 and therefore the valency of group 18 is 0 I.e they are stable.

◾When we go down the group the valency of all elements in that group remains same i.e the valency of whole group remains same but just the number of shells increases.

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Answer 2

a) A noble gas-H,P

Noble gases are neon, Argon

b)A halogen-GO

Halogns are flourine, chlorine

c)An alkali metal-A,I

Alkali metals are lithium and sodium

d)An element with valency 4-D,L

Element with tetravalency are carbon and silicon.