Question

Justify that the fifth period of the periodic table should have 18 elements on the basis of quantum numbers.(with full explanation).

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Answer 1

Answer:

In 5th period n = 5, and l = 0, 1, 2, 3. The order in which the energy of the available orbitals 4d, 5s and 5p increases is 5s < 4d < 5p. The total number of orbitals available is 9. The maximum number of electrons that can be accommodated is 18, and therefore 18 elements are there in the 5th period.