Question

Consider the following elements:
₂₀Ca, ₈O, ₁₈Ar, ₁₆S, ₄Be, ₂He
Which of the above elements would you expect to be:

(i) very stable?
(ii) in group 2 of the periodic table?
(iii) in group 16 of the periodic table?

Answer 1

(i) ₁₈Ar and ₂He are very stable elements, as their valance shells are completely filled. They belong to the group of inert or noble gases.

(ii) ₂₀Ca and ₄Be are the two elements that belong to group 2 of the periodic table. This is because their valency is 2 and they are electropositive.

(iii) ₈O (2,6) and ₁₆S (2,8,6) are the two elements that belong to group 16 of the periodic table.
      Group number = Valence shell + 10
                               = 6 + 10 = 16