627 articles
All articles — Page 3
Every article in the chemistry library, newest first.
Teaching Chemical Nomenclature: A Lesson Sequence That Sticks
A teaching guide to naming compounds: two timed lessons, ion-card and sorting activities, the naming errors students make and graded questions to check them.
Teaching Molecular Shapes with VSEPR
A VSEPR teaching guide: lesson timings, balloon and model-kit activities, the misconceptions students bring (flat drawings, ignored lone pairs) and graded questions.
Four Types of Solids: Ionic, Molecular, Covalent Network and Metallic
Ionic, molecular, covalent network and metallic solids compared side by side: particles, forces, melting points, conductivity and how to tell them apart.
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.
Alloys: Why Mixing Metals Makes Them Stronger
What alloys are, substitutional vs interstitial alloys, why different-sized atoms stop layers sliding, and the chemistry of steel, bronze, brass, solder, duralumin, gold alloys and shape-memory metals.
Amylase and Starch: Timing Digestion
A school practical timing how fast amylase digests starch using iodine and a spotting tile — the chemistry, a full method, rate calculations, graphs and sources of error.
ATP vs ADP
ATP vs ADP compared: structure, phosphoanhydride bonds, why hydrolysis releases energy, the ATP–ADP cycle, how ATP is regenerated, AMP as a signal and common misconceptions.
Blood Sugar Regulation: A Chemical Feedback Loop
How the body holds blood glucose near 5 mmol/L: negative feedback, insulin and glucagon, the liver as a glucose buffer, cell signalling, amplification, and what goes wrong in diabetes.
Ranking Boiling Points Using Intermolecular Forces
A step-by-step method for ranking boiling points, with seven worked examples covering hydrocarbons, isomers, alcohols vs ethers, halogens, hydrides, ionic and covalent substances.
Bond Angles: Why Water Is Bent at 104.5°
Why bond angles take the values they do: electron-pair repulsion, lone pairs, electronegativity, atom size and multiple bonds — explained through water, ammonia, methane and more.
Bond Enthalpy Calculations with Worked Examples
Six fully worked bond enthalpy calculations — from hydrogen and chlorine to combustion of methane and ethanol, a reverse calculation and a comparison with Hess's law data.
Bond Length and Bond Strength: How They Relate
What bond length and bond strength (bond enthalpy) mean, how they're measured, why shorter bonds are usually stronger, the trends down a group and across bond orders, and the exceptions.
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.
Bond Polarity: Using Electronegativity Differences
How to decide whether a bond is non-polar, polar covalent or ionic using Pauling electronegativity differences, with partial charges, worked examples, percent ionic character and effects.
Chemical Bonding Misconceptions (Including "Breaking Bonds Releases Energy")
Ten stubborn chemical bonding misconceptions — breaking bonds releases energy, atoms want full shells, NaCl molecules, boiling breaks bonds and more — each corrected with the real chemistry.
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.
The Chemistry of Muscle Contraction
Muscle contraction at the molecular level: actin and myosin, the sliding filament model, the ATP-driven cross-bridge cycle, calcium, troponin and tropomyosin, rigor mortis and cramps.
Nerve Impulses: Sodium, Potassium and Membrane Potential
The electrochemistry of nerve impulses: ion gradients, the Nernst equation, resting potential, voltage-gated channels, the action potential, myelin, synapses and toxins.
Separating Leaf Pigments by Chromatography
A school lab guide to separating chlorophylls and carotenoids from spinach by paper or thin-layer chromatography, with the chemistry, method, Rf values and sources of error.
Common Ions and Their Charges: A Reference List
A reference list of common cations and anions with charges — main-group ions, transition metal ions, polyatomic ions and oxyanions — with patterns from the periodic table that make them easy to remember.
Dative (Coordinate) Covalent Bonds Explained
What a dative covalent bond is, how to recognise and draw one, and key examples: ammonium, hydronium, NH₃BF₃, aluminium chloride dimers, carbon monoxide and metal complexes.
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.
Counting Sigma and Pi Bonds in Molecules
Worked examples for counting σ and π bonds — from ethene and CO₂ to benzene, aspirin and caffeine — with a fast method, a formula-based shortcut and common traps.
Covalent Bonding: Sharing Electrons Explained
Covalent bonding for beginners: why non-metals share electrons, how many bonds each atom forms, single, double and triple bonds, lone pairs, simple vs giant structures and properties.
The Criss-Cross Method for Ionic Formulas
How the criss-cross (swap and drop) method writes ionic formulas quickly, why it works, how to simplify, how to handle polyatomic ions, worked examples, and the cases where it goes wrong.
How to Determine the Hybridisation of Any Atom
A reliable step-by-step method for finding the hybridisation of any atom — count sigma bonds and lone pairs — with 12 worked examples and the tricky cases involving resonance.
Dipole–Dipole Forces Explained
How permanent dipole–dipole forces arise between polar molecules, how they compare with London forces and hydrogen bonds, worked boiling-point comparisons, and where they matter.
Dipole Moments: Why Some Molecules Are Polar
What a dipole moment is, how it's calculated and measured in debyes, how bond dipoles add as vectors, why shape decides polarity, and how dipole moments affect boiling points and solubility.
How to Draw Dot-and-Cross Diagrams
A step-by-step method for dot-and-cross diagrams of covalent molecules and ionic compounds, with worked examples from H₂ to CO₂, NaCl and MgO, and the most common mistakes.
Electron Geometry vs Molecular Geometry
The difference between electron-domain geometry and molecular shape, with a complete comparison table, worked examples from CH₄ to XeF₄, and the most common exam mistakes.