Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Why does 4s have a lower energy level than the 3d?

    thanks
    Offline

    19
    ReputationRep:
    (Original post by Patience12)
    Why does 4s have a lower energy level than the 3d?

    thanks
    The ordering of 4s vs 3d depends very much on the atom in question. The 4s orbital has an inner node, which means that there is electron density close to the nucleus. However, as you go across the fourth period, the 3d energy falls much faster than the 4s — the inner node in 4s screens the increasing Zeff somewhat from the outer electron density, leading to reduced orbital contraction.

    So for the transition metals, the 3d orbital is lower in energy than 4s, but the greater electron repulsion associated with sticking electrons in the smaller 3d orbitals outweighs this and the 4s is filled first.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: October 8, 2013

University open days

  • Southampton Solent University
    All faculties Undergraduate
    Sun, 18 Nov '18
  • University of Bradford
    All faculties Undergraduate
    Wed, 21 Nov '18
  • Buckinghamshire New University
    All Faculties Postgraduate
    Wed, 21 Nov '18
Poll
Black Friday: Yay or Nay?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.