627 articles
All articles — Page 16
Every article in the chemistry library, newest first.
Rutherford's Gold Foil Experiment: How the Nucleus Was Found
The story of the Geiger–Marsden experiment in Manchester: why alpha particles were fired at gold foil, what Thomson's model predicted, the shock of particles bouncing back, Rutherford's 1911 nuclear model, how the results were analysed, what the model couldn't explain, and why this experiment still matters.
The Rydberg Equation with Worked Examples
How to use the Rydberg equation 1/λ = R(1/n₁² − 1/n₂²) for hydrogen and one-electron ions: the Rydberg constant, calculating wavelengths of Lyman, Balmer and Paschen lines, finding the upper level from a wavelength, series limits, ionisation energies and common mistakes.
How to Read a Safety Data Sheet (SDS)
A section-by-section guide to the 16-part Safety Data Sheet: hazard classification, H and P statements, first aid, firefighting, spill response, handling and storage, exposure limits and PPE, physical properties, stability, toxicology and disposal, with a worked example for a common lab chemical.
What Is a Salt in Chemistry?
Salt means far more than table salt. The chemical definition, how salts form, their structure and properties, soluble vs insoluble salts, hydrated salts and the salts you meet every day.
Salt Hydrolysis: Why Some Salts Are Acidic or Basic
Why dissolving a salt can change the pH of water: how cations and anions react with water, the four salt types, hydrated metal ions, and how to predict whether a salt solution is acidic, neutral or basic.
Salt Hydrolysis Practice Problems
12 practice problems on the pH of salt solutions: classifying salts, calculating pH with Ka and Kb, metal ion hydrolysis, amphiprotic salts, finding Ka from a salt's pH, and equivalence-point pH in titrations.
Sampling: Why the First Step of Analysis Matters Most
Why a perfect measurement on a bad sample gives a wrong answer: representative samples, heterogeneity, random, systematic and composite sampling, how much sample to take, subsampling by coning and quartering, preservation, chain of custody, and worked examples from soil, water and food.
The Schrödinger Equation: What Chemists Actually Need to Know
A chemist's guide to the Schrödinger equation without heavy mathematics: what Ĥψ = Eψ means, the Hamiltonian and wavefunction, why solutions give quantised energies, the particle in a box, what the hydrogen atom solutions produce (orbitals and quantum numbers), approximations for many-electron atoms and molecules, and computational chemistry.
Serotonin: Structure and Roles
A chemical profile of serotonin (5-hydroxytryptamine): its indole structure, how it's made from tryptophan, why most of it is in the gut, its roles in mood, sleep, appetite and blood clotting, how SSRIs and psychedelics act on it, and its conversion to melatonin.
Shells vs Subshells vs Orbitals: Untangling the Terminology
A clear comparison of electron shells, subshells and orbitals: what each term means, how they nest inside each other, how many electrons each holds, how they relate to quantum numbers and the periodic table, and a worked example taking one atom through all three levels of description.
Slater's Rules: Calculating Effective Nuclear Charge Step by Step
Worked examples of Slater's rules for estimating shielding and effective nuclear charge: grouping orbitals, shielding contributions for s/p and d/f electrons, calculations for nitrogen, sodium, chlorine, zinc and potassium, using Zeff to explain 4s vs 3d and ionisation trends, and the rules' limitations.
Term Symbols and Spectroscopic Notation for Beginners
What does ³P₀ or ⁵D₄ mean? A step-by-step method for writing the ground-state term symbol of any atom using Hund's rules, with worked examples from carbon to iron and practice questions.
Spectroscopy Misconceptions
Eleven misconceptions students hold about spectroscopy and mass spectrometry, corrected with clear explanations: why coloured solutions absorb the opposite colour, what IR bands really measure, why the tallest mass spectrum peak isn't always the molecular ion, what NMR splitting counts, and more.
Spectroscopy: How Light Reveals Structure
An overview of spectroscopy for chemistry students: the electromagnetic spectrum, what each type of radiation does to atoms and molecules, and how UV–visible, infrared, NMR, mass spectrometry and atomic spectroscopy are used.
Spectroscopy Practice Questions
Advanced practice problems combining mass spectrometry, infrared, ¹³C NMR and ¹H NMR to deduce structures, from single-technique questions to full combined-data problems, each with a step-by-step worked answer and the reasoning behind every deduction.
Electron Spin: What the Spin Quantum Number Really Means
What electron spin is and isn't: the Stern–Gerlach experiment, the values +½ and −½, why spin is an intrinsic quantum property rather than literal rotation, its role in the Pauli principle, Hund's rule and magnetism, spin pairing in bonds, and applications in NMR, MRI, ESR and spintronics.
Standard Deviation in Chemistry Data
Worked examples of standard deviation for chemistry: calculating sample standard deviation step by step, relative standard deviation, standard error of the mean, 95% confidence intervals with t-values, comparing two methods, and the Q-test and Grubbs' approach for outliers.
The Iodine Test for Starch
A school-lab guide to the iodine test for starch: why iodine turns blue-black inside the amylose helix, a safe method for foods and solutions, testing leaves for photosynthesis and following starch digestion by amylase, with sources of error.
Steroids: The Four-Ring Molecules
The chemistry of steroids: the four fused rings, numbering, how cholesterol becomes cortisol, testosterone and oestradiol, how steroid hormones act on genes, vitamin D, steroid drugs, and the yam chemistry that made the contraceptive pill possible.
Stomach Acid: How Strong Is It Really?
The real chemistry of gastric acid: how the stomach makes hydrochloric acid, its concentration and pH, why it doesn't digest the stomach, what heartburn is, and how antacids and acid-reducing medicines work.
The Strong Acids (and Why There Are So Few)
The complete list of common strong acids, their formulas, estimated pKa values and uses, why hydrofluoric acid isn't on it, and how water levels them all to the same strength.
The Strong Bases: A Complete Guide
Which bases count as strong, why the Group 1 and heavier Group 2 hydroxides fully dissociate, the solubility catch with calcium hydroxide, superbases, and safe handling.
How to Interpret Successive Ionization Energy Graphs
A step-by-step guide to reading successive ionisation energy data and graphs: why each ionisation energy is larger than the last, how big jumps reveal the group and the number of outer electrons, using log graphs to see shells and subshells, worked examples for sodium, aluminium, silicon and an unknown element, and exam tips.
Superacids: Acids Stronger Than Pure Sulfuric Acid
What superacids are, how the Hammett acidity function measures acids beyond pH, famous examples from triflic acid to magic acid and fluoroantimonic acid, how they work, and why chemists use them.
Superbases: The Strongest Bases Known
What makes a base 'super', why hydroxide is the limit in water, and the chemistry of organolithiums, metal amides, hydrides, phosphazenes and the 'ortho-diethynylbenzene dianion', with their uses in synthesis.
Teaching Acids and Bases: Practical Ideas
A teacher's guide to acids and bases: a lesson sequence, practicals and demonstrations that work, the misconceptions to expect, questioning strategies and differentiated activities for mixed-ability classes.
Teaching the History of Atomic Models
A teacher's guide to the history of atomic models: a lesson sequence built around evidence, the Rutherford scattering simulation, black-box activities, misconceptions to expect and questions that test scientific reasoning.
Teaching Atomic Structure: A Lesson Plan and Activities
A practical guide for teachers on teaching atomic structure: a five-lesson sequence, hands-on activities (the mystery box, scale models, modelling the gold foil experiment, isotope 'beans'), questioning strategies, common misconceptions to target, assessment ideas and differentiation.
Teaching Buffers Conceptually
A teacher's guide to buffers: building intuition before equations, a demonstration that makes buffering visible, the particle-level story, common misconceptions, Henderson–Hasselbalch scaffolding and biological contexts.
Teaching Chromatography
A teacher's guide to chromatography lessons: a hook activity, explaining separation with analogies, running reliable paper and TLC practicals, common student misconceptions, Rf calculations, linking to GC and HPLC, differentiation ideas and assessment questions.