ch19 gcii

What is the general order of orbital filling in atoms?

s→p→d→f. 'In general, the order that orbitals fill… s → p → d → f.'

Why are orbitals degenerate in hydrogen but not in multielectron atoms?

Hydrogen has only one electron; in multielectron atoms, shielding destabilizes orbitals differently. 'Inner electrons shield the outer electrons… leading to different energies.'

Why is 4s lower in energy than 3d?

4s penetrates closer to the nucleus, lowering its energy relative to 3d. '4s allows for closer actual approach… therefore 4s is energetically preferred.'

Which electrons are lost first when forming transition‑metal cations?

4s electrons are removed before 3d electrons. '4s orbitals also empty first; all transition metal ions lose their 4s electrons first.'

What stabilizes half‑filled and fully filled subshells?

Reduced electron–electron repulsion and increased exchange energy. 'Full shells and half‑full shells are unexpectedly stable.'

Why is Cr = [Ar] 4s¹ 3d⁵ instead of [Ar] 4s² 3d⁴?

Moving one electron to 3d gives a half‑filled d⁵ configuration, lowering energy. 'Cr is more stable with the 4s electrons unpaired.'

Why is Cu = [Ar] 4s¹ 3d¹⁰?

A filled d¹⁰ subshell is unusually stable. 'The same concepts apply for group 11…'.

Example: What is Fe²⁺ electron configuration?

[Ar] 3d⁶. 'Fe²⁺ → [Ar]3d⁶.'

Example: What is Fe³⁺ electron configuration?

[Ar] 3d⁵. 'Fe³⁺ → [Ar]3d⁵.'

Why are transition metals harder, denser, and have higher melting points than s‑block metals?

They form stronger metallic bonds due to involvement of d electrons. 'Sharing of d, as well as s, electrons results in stronger bonding.'

What causes the lanthanide contraction?

Poor shielding by 4f electrons → increased Zeff → smaller radii. 'Electrons added to the same shell only partially shield… effective nuclear charge increases.'

Why are 3rd‑row transition metals extremely dense?

Very high mass + radii similar to 2nd row (due to lanthanide contraction). '3rd series… similar atomic radii… therefore MUCH larger densities.'

Why do ionization energies increase across a transition series?

Increasing Zeff and decreasing atomic radius. 'Correlated with the increase in effective nuclear charge…'.

Why do transition metals show many oxidation states?

Similar energies of 3d and 4s orbitals allow variable electron loss. '3d and 4s orbitals have similar energies…'.

Which oxidation state is most common for first‑row metals?

+2 (loss of two 4s electrons). 'All the first‑series transition metals (except Sc) form a 2+ cation.'

What stabilizes high oxidation states?

Bonding with electronegative ligands like O and F. 'In highest oxidation states… combine with the most electronegative elements (F and O).'.

Which ions are strong oxidizing agents?

High‑oxidation‑state ions like Cr₂O₇²⁻, MnO₄⁻. 'Transition metal ions in high oxidation states tend to be good oxidizing agents.'

Which ions are strong reducing agents?

Early transition metals in low oxidation states (e.g., V²⁺, Cr²⁺). 'Early transition metal ions in low oxidation states tend to be good reducing agents.'

Define ligand.

A Lewis base that donates an electron pair to a metal center. 'Ligands… have one or more electron pairs to donate.'

Define coordination number.

Number of donor atoms bonded to the metal. 'Coordination Number: The number of ligand donor atoms…'.

Monodentate vs. polydentate?

Mono = one donor atom; poly = multiple donor atoms. 'Monodentate… single donor atom… Polydentate… two or more donor atoms.'

What is a chelate?

A complex containing polydentate ligands that 'claw' the metal. 'A chelating ligand holds the metal ion like a crab’s claw.'

Order of naming in a complex ion?

Ligands (alphabetical) → metal → oxidation state. 'Name ligands first then the metal… alphabetical order.'

When do you use bis-, tris-, tetrakis-?

When ligand names already contain Greek prefixes. 'If the name of a ligand contains a Greek prefix… use bis-, tris-, tetrakis-…'.

How do you name an anionic complex?

Add '‑ate' to the metal name (often Latin). 'When the complex is an anion, add the suffix -ate…'.

Ionization isomers?

Differ by which ion is inside vs. outside the coordination sphere. '(A free bromide ion)… (A free sulfate ion).'.

Cis vs. trans isomers?

Cis = adjacent; trans = opposite. '(adjacent – cis)… (opposite – trans).'.

What makes a complex chiral?

No plane of symmetry; non‑superimposable mirror images. 'Chiral… nonidentical mirror images.'

What is a racemic mixture?

1:1 mixture of enantiomers with no net optical rotation. 'Racemic mixture – a 1:1 mixture… produces no net optical rotation.'

What causes color in transition‑metal complexes?

d–d transitions between split d orbitals. 'Colors… attributed to electronic transitions between the eg and t2g orbitals.'

Relationship between Δ and λ?

λ=hcΔE. 'λ = hc/ΔE.'

What determines the complementary color observed?

The color not absorbed. 'Light that isn’t absorbed… this is the complementary color you see.'

In valence bond theory, how do ligands bond?

Ligand lone pairs overlap metal hybrid orbitals. 'Bonding… arises when a filled ligand orbital… overlaps a vacant hybrid orbital.'

Hybridization for octahedral complexes?

d2sp3 or sp3d2. 'Octahedral → d²sp³ or sp³d² hybrids.'

High‑spin vs. low‑spin?

High‑spin = weak field, small Δ, paramagnetic; low‑spin = strong field, large Δ, diamagnetic. 'Weak field → high‑spin… Strong field → low‑spin.'

What is the core assumption of crystal field theory?

Purely electrostatic interactions; no covalent bonding. 'NO covalent bonds, NO shared electrons…'.

Which d orbitals are raised in octahedral fields?

dx2−y2 and dz2 (the eg set). 'Better overlap… dx²–y² and dz².'

What determines the magnitude of Δ?

Ligand strength (spectrochemical series). 'Crystal field splitting increases across a spectrochemical series.'

Given λ = 499 nm, how do you compute Δ?

Use Δ=hcλ, then convert J → kJ/mol. 'Absorption maximum at 499 nm… calculate Δ.'