627 articles
All articles — Page 10
Every article in the chemistry library, newest first.
Concentrated vs Strong: Two Words Students Mix Up
Strength is about how completely an acid ionises; concentration is about how much is dissolved. Clear definitions, a four-way comparison, pH examples and exam-ready wording.
Conductometric Titrations
How following electrical conductivity during a titration reveals the end point without an indicator: why H⁺ and OH⁻ conduct so well, the V-shaped graphs for strong and weak acids, precipitation titrations, and practical tips.
How to Identify Conjugate Acid–Base Pairs
A reliable four-step method for finding conjugate acids and bases in any equation, how to write the conjugate of a given species, polyprotic ladders, and 20 practice questions with answers.
Core Electrons vs Valence Electrons
The difference between core and valence electrons: definitions, how to count each for main-group and transition elements, why valence electrons control bonding and reactivity while core electrons shield the nucleus, links to group number, Lewis symbols and ionisation energy jumps, and worked examples.
Dalton's Atomic Theory: Five Ideas That Launched Modern Chemistry
The story of John Dalton, the Quaker schoolteacher from Manchester whose atomic theory of 1803–1808 turned atoms from philosophy into science: the laws that inspired it, his five key ideas, his symbols and early atomic weights, what he got wrong, and why his theory still shapes chemistry.
The de Broglie Wavelength with Worked Examples
Worked examples using λ = h/mv: wavelengths of electrons, protons, neutrons, atoms and everyday objects, electrons accelerated through a voltage, comparing with atomic spacings, finding speed from wavelength, why large objects show no wave behaviour, and the link to Bohr's orbits.
Democritus and the Ancient Greek Idea of the Atom
Twenty-four centuries ago, Leucippus and Democritus argued that everything is made of tiny, uncuttable pieces moving through empty space. Here is how the idea began, why it was rejected, and how it survived.
Protein Denaturation: Why Eggs Turn White When Cooked
What happens when proteins lose their shape: how heat, pH, salts, heavy metals, solvents and mechanical stress denature proteins, which bonds break and which survive, reversibility, and everyday examples from cooking eggs to perming hair.
Disaccharides: Sucrose, Lactose and Maltose
How two sugars join through a glycosidic bond: the condensation and hydrolysis reactions, sucrose, lactose and maltose compared, α and β linkages, why sucrose is non-reducing, invert sugar and lactose intolerance.
DNA Replication: The Chemistry
DNA replication from a chemist's point of view: semiconservative copying, the Meselson–Stahl experiment, helicase and topoisomerase, why polymerases only build 5′→3′, the phosphodiester-forming reaction and its energy, leading and lagging strands, proofreading and PCR.
The Structure of DNA: The Double Helix
The chemistry of the DNA double helix: antiparallel strands, complementary base pairs, the sugar–phosphate backbone, major and minor grooves, dimensions, what holds the helix together, and how Franklin, Watson and Crick worked it out.
DNA vs RNA
DNA and RNA compared side by side: sugar, bases, strands, stability, location, types and jobs, with the chemistry behind each difference, why RNA is less stable, the RNA world idea and a quick-check quiz.
Dopamine: Chemistry and Function
A chemical profile of dopamine: its catecholamine structure, how it's made from tyrosine and broken down, its pathways in the brain, its real role in movement, motivation and reward prediction, Parkinson's disease and L-DOPA, and how drugs affect it.
How Drug Tests Work: Immunoassays and GC-MS
The chemistry behind workplace, sports and roadside drug tests: why labs look for metabolites, how antibody-based immunoassay screens work, cut-off levels, false positives, and why every positive screen is confirmed by GC-MS or LC-MS/MS.
Effective Nuclear Charge and Shielding: The Engine Behind Periodic Trends
An advanced explanation of effective nuclear charge (Zeff) and shielding: why outer electrons feel less than the full nuclear charge, how penetration makes s electrons feel more, how Zeff changes across periods and down groups, and how it explains atomic radius, ionisation energy, electronegativity, the 4s–3d order and the lanthanide contraction.
Electron Configurations of Ions: Cations, Anions and Transition Metals
Worked examples for writing electron configurations of ions: main-group cations and anions, isoelectronic species, why transition metals lose 4s electrons before 3d, Fe²⁺ and Fe³⁺, Cu⁺ and Cu²⁺, Cr³⁺, counting unpaired electrons, and linking configurations to ion stability and colour.
Electron Configuration Practice Questions with Full Answers
Thirty electron configuration practice questions in five graded sets, from writing configurations for light elements to transition metal ions, exceptions, identifying elements from configurations, excited states and exam-style explanations, each with a full worked answer.
Electron Clouds and Probability: Why Orbitals Aren't Orbits
Why modern chemistry describes electrons as clouds of probability rather than particles on tracks: the wavefunction and ψ², dot-density pictures, 90% boundary surfaces, radial probability and the most probable distance, how the cloud picture explains atomic size, bonding and electronegativity, and common misconceptions.
Electron Shells: The 2, 8, 8 Rule and Where It Comes From
A beginner's guide to electron shells: how to fill shells for the first 20 elements with the 2, 8, 8 pattern, drawing shell diagrams, why the third shell 'pauses' at 8, how shells explain groups and periods, valence electrons and reactivity, and when the simple shell model stops working.
Electron Shell Diagrams Practice (First 20 Elements)
Practice drawing and interpreting electron shell diagrams for the first 20 elements: 2,8,8,2 arrangements, ions, groups and periods, with a complete answer key and a reference table.
The Electron Transport Chain
How mitochondria turn NADH into ATP: the four complexes, ubiquinone and cytochrome c, redox potentials and the energy released, proton pumping and Mitchell's chemiosmotic theory, ATP synthase as a rotary motor, ATP yields, poisons and uncouplers.
Gel Electrophoresis: Separating DNA and Proteins
How gel electrophoresis separates molecules by size and charge in an electric field: why DNA moves towards the positive electrode, agarose vs polyacrylamide gels, DNA ladders, SDS-PAGE for proteins, staining, reading a gel, and uses in forensics, medicine and research.
Elemental (CHN) Analysis
How a CHN analyser burns a milligram sample to measure carbon, hydrogen, nitrogen and sulfur, how oxygen is found, the classic Pregl and Liebig methods, worked calculations to an empirical formula, the ±0.4% purity rule, and the limits of the technique.
Emission vs Absorption Spectra: How Atoms Reveal Themselves
A comparison of emission and absorption spectra: continuous vs line spectra, bright lines on a dark background vs dark lines in a rainbow, why the lines appear at the same wavelengths, Kirchhoff's laws, Fraunhofer lines in sunlight, the discovery of helium, and uses in chemical analysis and astronomy.
Endorphins: The Body's Natural Painkillers
What endorphins are: peptides that act on the same receptors as morphine, how they were discovered, how they're made and work, when the body releases them, the truth about the 'runner's high', and how opioid drugs and naloxone relate to them.
Measuring the Enthalpy of Neutralisation
A complete practical guide to measuring the enthalpy change when an acid neutralises an alkali: method, results table, extrapolation graph, calculation, why strong acids all give about −57 kJ/mol, and how to improve accuracy.
Investigating Enzyme Activity: Catalase and Amylase
Two school-lab-safe enzyme practicals with full methods: measuring catalase activity from oxygen gas volume, and timing amylase digestion of starch with iodine, including variables, results tables, rate calculations and sources of error.
Competitive vs Non-competitive Inhibition
How enzyme inhibitors work: competitive, non-competitive and uncompetitive inhibition compared, their effects on Km and Vmax, Lineweaver–Burk patterns, irreversible inhibitors, feedback inhibition, and real drugs and poisons.
Enzyme Kinetics: Michaelis–Menten Explained
Michaelis–Menten kinetics made clear: the reaction scheme, the saturation curve, deriving v = Vmax[S]/(Km + [S]), what Km, Vmax and kcat mean, catalytic efficiency, Lineweaver–Burk plots and a fully worked example.
Enzymes: How They Work
A beginner's guide to enzymes: what biological catalysts are, how active sites and substrates fit, how enzymes lower activation energy, specificity, naming, the factors that affect activity, and enzymes at work in the body and industry.