Question
Give scientific Reason :
The third period contains only eight elements even though the electron capacity of the third shell is 18.

Answer

(i) Period 3 of the periodic table consists of elements whose atom has three shells occupied by electrons.
(ii) As per the electron holding capacity of shells, 2 elements are present in the first period, and 8 elements in the second period.
(iii) The third period also contain only eight elements due to the law of electron octet and also electrons will fill orbitals in increasing order of energy, i.e. the lowest energy orbital first.

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