Transition Metals & Coordination Chemistry – Exam Review Vocabulary

A set of vocabulary flashcards covering definitions and key terms about transition metals, their electronic structure, coordination chemistry, furnace iron extraction, and crystal field concepts for exam preparation.

Transition Metal

An element whose atoms form ions with partially filled d-orbitals, displaying properties such as variable oxidation states and colored compounds.

d-Block

The block of the periodic table containing groups 3–12 where the (n–1)d orbitals are being filled.

General Electron Configuration of Transition Metals

(n–1)d¹–¹⁰ ns¹–², with 4s electrons filled before 3d but removed first upon ionisation.

Variable Oxidation States

Characteristic of transition metals; ability to form ions in several oxidation numbers due to similar energies of 4s and 3d subshells.

Colored Compound

A substance that absorbs specific wavelengths of visible light, often produced by d–d transitions in transition-metal complexes.

Catalytic Activity

Ability of transition metals or their compounds to speed up reactions by providing alternative pathways with lower activation energy.

Magnetic Behavior

Paramagnetism or diamagnetism arising from unpaired or paired d-electrons in transition-metal ions/complexes.

Ligand

An electron-pair donor that forms a coordinate covalent bond with a metal center.

Monodentate Ligand

Ligand that binds through a single donor atom, e.g., Cl⁻, NH₃, H₂O, CN⁻.

Bidentate Ligand

Ligand that binds through two donor atoms, e.g., ethylenediamine (en), oxalate (C₂O₄²⁻).

Polydentate Ligand

Ligand possessing multiple donor atoms; example: EDTA⁴⁻ (hexadentate).

Coordination Complex

Species consisting of a central metal atom/ion bonded to surrounding ligands via coordinate covalent bonds.

Coordination Number

Total number of ligand donor atoms bonded directly to the metal center (common values: 4, 6).

Oxidation State (in Complexes)

Charge on the metal determined by: metal oxidation state = overall complex charge − sum of ligand charges.

Hexacyanidoferrate(III) Ion

[Fe(CN)₆]³⁻; Fe is in the +3 oxidation state with six cyanide ligands (coordination number 6).

Tetraamminecopper(II) Ion

[Cu(NH₃)₄]²⁺; copper(II) complex with four ammonia ligands (coordination number 4).

Hexaaquachromium(III) Chloride

[Cr(H₂O)₆]Cl₃; neutral octahedral complex cation balanced by three chloride anions.

Isomerism (in Complexes)

Existence of coordination compounds with the same formula but different structures or spatial arrangements.

Geometric Isomerism

cis/trans or fac/mer arrangements of ligands in octahedral (and square-planar) complexes.

Optical Isomerism

Presence of non-superimposable mirror-image (enantiomeric) complexes, often with bidentate ligands.

Linkage Isomerism

Isomers where the same ambidentate ligand binds through different atoms (e.g., nitro-N vs. nitrito-O).

Crystal Field Theory (CFT)

Model describing d-orbital splitting (t₂g/e_g) in a metal ion under the influence of surrounding ligands.

Crystal Field Splitting Energy (Δ)

Energy gap between t₂g and e_g sets in an octahedral complex; size depends on ligand field strength.

Spectrochemical Series

Order of ligands from weak-field (small Δ) to strong-field (large Δ), influencing spin states and color.

High-Spin Complex

Complex where Δ is small; electrons occupy higher e_g orbitals before pairing, giving more unpaired electrons (paramagnetic).

Low-Spin Complex

Complex where Δ is large; electrons pair in lower t₂g orbitals first, often resulting in fewer unpaired electrons (possibly diamagnetic).

Paramagnetism

Magnetic property arising from one or more unpaired electrons; attracted to an external magnetic field.

Diamagnetism

Magnetic property of substances with all electrons paired; weakly repelled by an external magnetic field.

d–d Transition

Electron promotion between split d-orbitals (t₂g ↔ e_g) absorbing specific light wavelengths, producing color.

Jahn–Teller Distortion

Structural distortion of non-linear complexes (notably d⁹) to remove degeneracy and lower energy, common in Cu²⁺ octahedral complexes.

Blast Furnace

Industrial reactor for extracting iron from hematite using coke and limestone at high temperatures.

Hematite

Fe₂O₃; principal iron ore fed into a blast furnace.

Coke

Carbon fuel and reducing agent in iron extraction, generating CO and heat.

Limestone

CaCO₃; decomposes to CaO, which forms slag by reacting with SiO₂ impurities.

Slag

CaSiO₃; molten waste layer formed from CaO and silica, removed separately from molten iron.

Fac/Mer Notation

Describes arrangement of three identical ligands in octahedral [MA₃B₃] complexes: facial (fac) or meridional (mer).

t₂g Orbitals

Lower-energy d-orbitals (dxy, dxz, d_yz) in an octahedral crystal field.

e_g Orbitals

Higher-energy d-orbitals (dx²–y², dz²) in an octahedral crystal field.

Unpaired Electron Count

Number of singly occupied orbitals in a complex, deduced from electron filling and used to predict magnetic properties.