Question #8510a

1 Answer
Aditya Banerjee.
Oct 5, 2017

Aufbau Principle is one of the pillars of the Quantum Theory. Let's see what it means :)

Explanation:

Aufbau Principle is related to atomic orbitals. It states that, "when a certain atom is in it's ground state or lowest energy state, electrons enter the atomic orbitals in a sequence from low energy orbitals to high energy orbitals".

Now, the relative energy of an atomic orbital is given by the following expression:

#color(green)(E=n+l)#. #larr# where, #color(red)("n")# is the Principle Quantum number & #color(blue)("l")# is the Azimuthal Quantum number.

Now, we have got #color(red)(7)# Principle Quantum numbers and #color(blue)(4)# Azimuthal Quantum numbers.

Now, the four Azimuthal quantum numbers are :
#o.##0 (s)#.
#o.##1 (p) #.
#o. ##2(d)#.
#o. ##3(f)#.

Now, more the #color(red)("n+l")# value higher the magnitude of energy of the atomic orbital.

An additional knowledge: if #color(blue)(""l"")# of two atomic orbitals are same, the atomic orbital with higher #color(red)(""n"")# value is assumed to have higher energy.

Accordingly, all the atomic orbitals are arranged according to the increasing order of their energies & electrons enter accordingly #rarr#

#color(red)(1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p)#

Hope it Helps :)

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