(solved)Question 3.4 of NCERT Class XI Chemistry Chapter 3

On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
(Rev. 05-May-2025)

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Question 3.4
NCERT Class XI Chemistry

On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.

Solution in Detail
(video solution below this)

The orbitals start filling from 6s1\displaystyle 6s^1 and continue till 6p6\displaystyle 6p^6.

the aufbau order is 6s<4f<5d<6p\displaystyle 6s \lt 4f \lt 5d \lt 6p

total orbitals 6s(1) + 4f(7) + 5d(5) + 6p(3) = 16.

by Pauli Exclusion Principle each orbital can have a maximum of 2 electrons.

\displaystyle \therefore total electrons = 16 x 2 = 32.

which justifies that period 6 can have 32 elements.

Video Explanation

Please watch this youtube video for a quick explanation of the solution:

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