627 articles
All articles — Page 4
Every article in the chemistry library, newest first.
Enzyme Misconceptions
Nine common misconceptions about enzymes — that they're alive, get used up, only work at 37 °C, or change the equilibrium — each corrected with the real chemistry.
Enzymes vs Hormones
Enzymes vs hormones compared: catalysts vs messengers, where they act, chemical types, speed, specificity, how they're controlled and how the two work together in the body.
Fats vs Oils
Fats vs oils side by side: the same triglyceride chemistry, why chain shape decides solid or liquid, sources, stability, cooking, hydrogenation and health.
Fermentation Biochemistry: Alcoholic and Lactic
The biochemistry of fermentation: why cells ferment, NAD⁺ recycling, the alcoholic pathway in yeast and the lactic pathway in muscle and bacteria, yields, and uses in food.
Fibrous vs Globular Proteins
Fibrous vs globular proteins compared: shape, sequence, solubility, bonding, stability and function, with collagen, keratin, haemoglobin and enzymes as worked examples.
How to Calculate Formal Charge (and Pick the Best Lewis Structure)
Step-by-step method for formal charge, with worked examples for CO₂, SCN⁻, NH₄⁺, CO, SO₄²⁻ and N₂O, the rules for choosing the best Lewis structure, and common mistakes.
Giant Covalent Structures: Diamond, Graphite and Silica
How diamond, graphite, graphene and silicon dioxide are built, and how their networks of covalent bonds explain their hardness, melting points, conductivity and uses.
Hybridisation: sp, sp2 and sp3 Orbitals Explained
Why carbon forms four equal bonds: the idea of hybrid orbitals, sp³, sp² and sp hybridisation with methane, ethene and ethyne, lone pairs in NH₃ and H₂O, and the limits of the model.
Hydrogen Bonding in DNA and Proteins
How hydrogen bonds hold DNA's base pairs together and shape proteins: donors and acceptors in A–T and G–C, why strands can separate, α-helices and β-sheets, and why weak bonds are ideal for biology.
Intermolecular Forces Practice Questions
15 exam-style questions on London forces, dipole–dipole forces, hydrogen bonds and ion–dipole forces — identifying forces, ranking boiling points and explaining solubility — with full answers.
Intramolecular vs Intermolecular Forces
Intramolecular forces (bonds within molecules) vs intermolecular forces (attractions between molecules): definitions, types, strengths, what each controls, and worked examples with water and iodine.
Ion–Dipole Forces and Why Salt Dissolves in Water
How ion–dipole forces let water pull ions out of a crystal: hydration shells, hydration enthalpy, the energy balance of dissolving, why charge and size matter, and why some salts don't dissolve.
Ionic Bonding: Transferring Electrons Step by Step
Ionic bonding step by step: electron transfer, ion charges from the periodic table, the energy balance and lattice energy, crystal lattices, properties, and how to work out formulas.
Ionic Lattices: The Structure of Sodium Chloride
Inside a salt crystal: the rock-salt lattice of NaCl, coordination numbers, unit cells, how ion size sets the structure (CsCl, zinc blende, fluorite), and how X-rays revealed it.
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.
Lewis Structures Practice: 20 Molecules and Ions with Answers
20 Lewis structure practice problems — from H₂O and CO₂ to SO₄²⁻, XeF₄ and ozone — with electron counts, full answers described step by step, formal charges and shapes.
"Like Dissolves Like": Solubility and Polarity
What 'like dissolves like' really means: polar and non-polar solvents, the energy and entropy of dissolving, why oil and water don't mix, how soap works, and exceptions to the rule.
How Molecules Cross Cell Membranes
The chemistry of membrane transport: why the lipid bilayer blocks ions, simple and facilitated diffusion, channels, carriers, pumps, co-transport, osmosis, and vesicles, with Fick's law.
London Dispersion Forces: The Weakest Force That Matters Most
What London dispersion forces are, how temporary dipoles form, why they grow with electron count, surface area and shape, and how they explain boiling points, geckos and why iodine is a solid.
How Lone Pairs Change Molecular Shape
What lone pairs are, why they take up more space than bonding pairs, and how they turn tetrahedral, trigonal bipyramidal and octahedral arrangements into bent, pyramidal, seesaw, T-shaped and square planar molecules.
How Metallic Bonding Explains Conductivity, Lustre and Malleability
The sea-of-electrons model of metallic bonding and how it explains why metals conduct electricity and heat, shine, bend without breaking, and have high melting points — with data and trends.
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.
How to Tell If a Molecule Is Polar
A four-step method to decide whether a molecule is polar: check bond polarity, find the shape, test for symmetry, and look for lone pairs — with 12 worked examples and quick shortcuts.
How to Name Acids: Binary Acids and Oxyacids
A step-by-step guide to naming acids: binary acids (hydro-…-ic acid), oxyacids from -ate and -ite ions, per- and hypo- prefixes, organic acids, and IUPAC vs traditional names, with practice.
Naming Compounds Practice: 40 Questions with Answers
40 naming and formula-writing practice questions — ionic, polyatomic, transition metal, covalent, acids and hydrates — graded from easy to hard, with a full answer key and explanations.
How to Name Hydrates
How to name hydrates and write their formulas: Greek number prefixes, the dot notation, anhydrous salts, worked examples like CuSO₄·5H₂O, finding x by experiment, and molar mass calculations.
Naming Compounds with Transition Metals (Roman Numerals)
How to name compounds of metals with variable charges using Roman numerals (Stock system): working out the metal's charge, worked examples, old -ous/-ic names, and common pitfalls.
Naming Oxyanions: -ate, -ite, per- and hypo-
How to name oxyanions using -ate, -ite, per- and hypo-, the chlorine series, patterns across the periodic table, hydrogen-containing oxyanions, oxidation states and the matching acid names.
Prions: Misfolded Proteins That Spread
How a protein can be infectious: the prion protein PrP, α-helix to β-sheet refolding, templated conversion, amyloid fibres, BSE and CJD, why prions resist sterilisation, and links to other diseases.
Properties of Covalent Compounds
The properties of covalent substances explained: low melting points and volatility of simple molecules, poor conductivity, solubility patterns, softness, and the very different giant covalent structures.