Question
Wed December 12, 2012 By: R Praveen
how is nth shell and penultimate (n-1)th shell incomplete in "D" block elements ? give example....
the electronic configuration of scandium (atomic no 21)  is 

about F block elements

Expert Reply
Fri December 14, 2012

Orbital Order

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 8s.

Although this looks confusing, there is an easy way to remember.

As 3d is filled first, it is more appropriate to write 3d first and then 4s.

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