TM Flashcards
How do you determine the ground state orbital angular momentum, L, of an electron config?
Disregard full subshells as no contribution to am
Add ml values for each e- (if two in same orbital then add twice) following Hunds rule
The highest L value is the ground state
Where |L|=0,1,2,3,4,5 is S,P,D,F,G,H
How can you evaluate the spin quantum number, S?
Add the unpaired spins of e-
What is the spin multiplicity of a term?
2S+1
Where S is the spin quantum number
What are the J-values of a term and ground state?
J = L+S, L+S-1,…|L-S|
When < half full orbital then Jmin is the lowest energy
When > half full orbital then Jmax is the lowest energy
How does spin multiplicity correspond to energy level?
Largest spin multiplicity is the most stable
What is the ground state when there is a half-filled orbital?
L = 0, and therefore J=S
Filled, 1/2 filled, or empty orbitals represent orbital singlets
How does the sublimation/energies change across the first TM period?
s has metallic band structure (s&d), no nodes in band
Ca → Cr there is an increase as fills the band and therefore more bonding
After this generally decreases as fills antibonding orbitals so bonding strength in solid decreases
Cr, Mn, Fe (lesser extent) low as no exchange energy in solid, spin energy gained in gas
Why is exchange energy available in gas and not in solid metallic band structure?
Valence e- in metallic bonding randomises relative spin and so increases e- e- repulsion relative to the exchange energy in free atom
Most relevant for d4, d5, d6 where most repulsion and exchange energy
What orbitals are stabilised and raised in energy in CFT theory for octa?

How does CFT fail?
Doesn’t describe true nature of chemical bonding or some effects
By how much are the t2g and eg stabilised/destabilised?
t2g stabilised by -2/5 ΔO
eg destabilised by 3/5 ΔO
What is the Barycentre?
Energy when there is a spherically uniform distribution of negative charges
In the MO picture, what orbitals are filled in the ligand field?
Bonding and non-bonding filled by ligand electrons
Valence e- from metal are in the eg* and t2g* which are mainly d orbital character
If the 3d orbital is lower E than 4s, why is 4s occupied in Sc and beyond?
3d orbital is compact, and outermost 4s lobe contains most of e- density so 4s is diffuse
e- e- repulsions are significant in the contracted 3d orbitals, so more favourable to be in slightly higher 4s
How does 4s, 3d and 4p change going from group 1 to 3?
3d lowers in energy across the groups as is more contracted so higher Zeff affects it more
3d lowers to less than 4s by Sc
What is the relation between orbtial energy and Zeff?
(revision)
Orbital energy ≈ -Zeff2/n2
What are the factors a 4s experiences across a period?
Innermost lobe experiences slow increase in nuclear charge
Outermost lobe effectively screened from increase in nuclear charge by 3d e- density
Why do neutral atoms in the 1st row of TM have 3dn-2 4s2 (or 3dn-1 4s1)?
Strong 3d electron repulsion
What occurs to 3d and 4s orbitals as ionisation occurs?
3d orbital has increased Zeff and contracts more rapidly than 4s
3d orbital contracts and penetrates core more
What are the microstates with L values?
2L+1 microstates with values from L,L-1,L-2, … -L+1,-L
Gives rise to 2J+1 microstates
How well do the 4s orbitals overlap with ligands?
Can overlap even better with ligands and make v stable bonding & v destabilised antibonding (compared to 3d)
Due to 4s being more diffused than the 3d
What symmetry do the eg and t2g orbitals overlap with?
eg - σ symmetry
t2g - π symmetry
What occurs to bonding strength as electrons are put into t2g* or eg*?
t2g* π* weakens bonding less than eg* σ*
What is the change of hydration enthalpies of M2+?
Hydration/lattice enthalpies should scale as 1/r (predict increase approx linearly)
Ca2+, Mn2+, Zn2+ are linear, others are more negative than expected
Due to LFSE from water in aq.
