135 articles
Bonding & Molecular Structure
Ionic, covalent and metallic bonds, molecular shapes, intermolecular forces and naming compounds.
Estimating Percent Ionic Character: Six Worked Examples
Six worked problems on percent ionic character: Pauling's electronegativity formula, working backwards to Δχ, and the dipole-moment method for HCl, HF and NaCl.
Ionic Crystal Structures: Rock Salt, Caesium Chloride, Zinc Blende and Fluorite
The four classic ionic lattices, grouped by coordination: what each looks like, its coordination numbers, which compounds adopt it, and why.
Isomerism in Coordination Complexes: Structural and Stereoisomers
Why one formula can give several different complexes: ionisation, hydrate, linkage and coordination isomers, cis–trans, fac–mer and optical isomers explained.
Lewis Structure of Sulfate: Octet vs Formal Charge
Six worked problems on SO₄²⁻: the all-single-bond and expanded-octet Lewis structures, formal charges, resonance, shape, and what modern bonding theory says.
Common Ligands: Monodentate, Bidentate and Chelating
A grouped list of 20 common ligands, from water and ammonia to en, oxalate, bipy, porphyrins and EDTA, with donor atoms, charges, denticity and why each matters.
How to Name Coordination Compounds (IUPAC Method)
A step-by-step IUPAC method for naming coordination compounds: ligand names, prefixes, alphabetical order, oxidation states, -ate endings and bridging ligands.
Pi Stacking and Aromatic Interactions
How flat aromatic rings attract each other: face-to-face, parallel-displaced and T-shaped geometries, the role of quadrupoles, and why the name is debated.
Unit Cells: Counting Atoms and Calculating Density
What a unit cell is, how to count atoms shared at corners, edges and faces, how to link cell size to atomic radius, and how to calculate density from a lattice.
Bond Order from Molecular Orbital Diagrams
Six worked examples calculating bond order from MO diagrams — H₂⁺, N₂, O₂ and its ions, NO, CN⁻ and C₂ — with electron configurations, magnetism predictions and bond length trends.
Born–Haber Cycles with Worked Examples
How to build and solve Born–Haber cycles step by step, with worked examples for NaCl, KCl, MgO and CaCl₂, finding lattice energy, electron affinity or enthalpy of formation.
Coordination Compounds: An Introduction to Complex Ions
An introduction to coordination compounds: central metal ions, ligands and dative bonds, coordination number and shape, chelates, naming complexes, colour, isomerism and uses in medicine and biology.
Lattice Energy: What Controls the Strength of Ionic Solids
What lattice energy is, sign conventions, how ion charge and size control it, trends with real data, theoretical vs experimental values and covalent character, and links to melting point and solubility.
Molecular Orbital Theory for Beginners
An accessible introduction to molecular orbital theory: combining atomic orbitals, bonding and antibonding orbitals, MO diagrams for H₂, He₂ and period 2 molecules, bond order and magnetism.
Valence Bond Theory vs Molecular Orbital Theory
Valence bond theory vs molecular orbital theory side by side: core ideas, how each describes H₂, O₂, benzene and methane, strengths, failures, and when chemists use each one.
Why Is Oxygen Paramagnetic? The MO Theory Answer
Liquid oxygen sticks to a magnet, but its Lewis structure says it shouldn't. How molecular orbital theory explains O₂'s two unpaired electrons, triplet and singlet oxygen, and why it matters for life.