Folks,

Unless I am mistaken, there are gross disagreements between Miessler & Tarr (5th ed) and the analyses by W. H. Eugen Schwarz (J. Chem. Ed. 2000, 435-443 and 444-448) about the energy levels of the valence orbitals in early transition metals and, subsequently, whether there are any electrons in 4s for the M⁺ ions.

A popular diagram (Figure 2.12) on p. 35 of M&T shows 4s below 3d up through vanadium and 1 electron in the 4s orbitals for each of Sc⁺, Ti⁺, Mn⁺, and Fe⁺.

Consistent with what is shown, the figure caption states "As a consequence, transition-metal ions with 2+ or greater charges have no s electrons, only d electrons in their outer levels."

On the following page (36), an italicized sentence is more general: "Transition metal cations have no s electrons, only d electrons in their outer levels."  Unless there is a typo here (missing 'with 2+ or greater charges'[?]), by itself this seems to be a contradition.

Page 438 of the first Schwarz reference includes the sentence "The d shell becomes the lowest, dominant valence shell of the transition metals from group 3 onward; the so-called d-orbital collapse is complete in group 3."

On page 436 of the same (in the Table 1 Q&A), it states "(n-1)d is always occupied first in transition metal cations.  The leading configuration of cations M^q+ of charges q from G [group number] through 0 is (n-1)d^G-qns⁰.  Only the chemically less important free neutral atoms in vacuum have an exceptional ns occupation."

In the subsequent Schwarz paper, on page 444 the energetic sequence of atomic orbitals is listed for K, Ca, and "Sc and subsequent":

K: 3p<<4s<4p<<3d<...

Ca: 3p<<4s<3d<4p<<...

Sc and subsequent: 3p<<3d<4s<4p<<...

A diagram on the same page, similar to that in M&T, shows 3d lower than 4s starting with Sc.  

And I am remembering now a similar diagram in my old Shriver and Atkins - I am finding it on page 20 of the 4th edition (showing 3d lower than 4s beginning at Sc).

Am I missing something here?  Does it have something to do with the fact that, in the p. 35 diagram, M&T is attempting to further show energy differences based on single vs. double occupancy?

I am currently looking a review from a POGIL activity I submitted for feedback that states "The titanium ground state energy diagram is incorrect. The 4s orbital should be lower than 3d in the ground state (Meissler + Tarr, 35)."

I would LOVE IT if someone who understands this material better than I do could straighten me out here.

Thanks as always.

- Joe