Sir why afte filling 6s we start filling electrons in 5d although 5d has higher energy than 4f

for both 4f and 5d n+l value is 7

But 4f has lower n value than 5d

So 4f is filled first before 5d

for unexpected behaviour read this

yes sir

thanku so much

you're welcome shweta😊

show me your you saw it

You might have mistaken something

use (n+l) rule.

you will get the explanation

sir

I am asking unexpected configuration for 6 th period

this

Sahi to hai. 4f me 14 element hai kyoki 4f can accommodate 14 eletron. After 14 eletron we have to fill 5d. We have no choice.

ni

CS ,ba fill krne Ke baad la aata ..so according to aufbau rule 4 f fill krna chahiye but HM 5 d krte hai sir

ok I got it 👍 . lanthanum you are asking right

Orbitals fill in order of energy. So 5D fills before 4F in some cases simply because the 5D energy levels are lower than the 4F levels for some. This does not occur for all the lanthanides. Cerium, where the increase in effective nuclear charge after Lanthanum is not sufficient to stabilize the 4F2 5D0 configuration compared to 4F1 5D1. The nuclear charge is insufficient to contract the 4F orbitals and lower their energy well below the 5D. 4F then fills first until Gadolinium is reached. Gadolinium has the F7 D1 configuration, consistent with a stabilized half-filled f shell

See this

use n+ l rule to fill electrons

check it sweta, 4f will fill first then, 5d

sir

I am asking that electronic configuration 6 th period ki unexpected kyin hai

this

??