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Development of practical skills in chemistry
1.1 - Practical skills assessed in a written examination
1.1.1 - Planning practical investigationsGood practical chemistry starts before any chemicals are mixed. In this lesson you will learn how to turn a practical problem into a method that can answer the question, using suitable apparatus, controlled variables and chemical reasoning. The aim is not to memorise one perfect method for every...
1.1.2 - Implementing measurements and observationsGood practical chemistry is not just "doing the experiment". It means choosing apparatus that matches the measurement, using it safely and correctly, recording observations precisely, and presenting raw data so that another chemist can understand what was actually measured. This lesson builds the...
1.1.3 - Analysis, graphs and significant figuresThis lesson is about turning practical results into evidence. You will learn how to process qualitative and quantitative results, choose sensible significant figures, draw and interpret graphs, and use gradients, intercepts and tangents to support a valid conclusion.
1.1.4 - Evaluation, uncertainty and improvementsGood practical chemistry does not end when the readings have been recorded. You need to decide what the results show, how much confidence the evidence deserves, and how the method could be made stronger. This lesson teaches the language for evaluating data: anomalies, limitations, accuracy, preci...
1.2 - Practical skills assessed in the practical endorsement
1.2.1 - Practical endorsement skillsPractical chemistry is not only about getting a result. It is about planning a sensible method, using equipment safely, making reliable observations, keeping records that someone else can understand, processing data correctly, and acknowledging where information came from. These skills are assess...
1.2.2a-c - Core measurement, heating and pH techniquesThis lesson is about choosing apparatus because it fits the measurement, not because it is familiar. You will learn how to record mass, time, volumes and temperature, how to heat mixtures using water baths, electric heaters and sand baths, and how to measure pH with charts, meters and probes.
1.2.2d-f - Volumetric glassware, reflux, filtration and indicatorsThis lesson is about using common wet-chemistry apparatus accurately and safely. You are not learning a long list of practical recipes; you are learning why each piece of apparatus is chosen, what accuracy it gives, and what details make an experimental method valid.
1.2.2g-l - Purification, chromatography, cells, rates and safetyThis lesson is about choosing and using practical techniques accurately. You will learn how to handle solid and liquid products differently, how to check purity or separation using melting point and chromatography, how to set up an electrochemical cell for a voltage reading, and how to measure re...
Foundations in chemistry
2.1 - Atoms and reactions
2.1.1a-b - Atomic structure and isotopesAtoms are the counting units of chemistry, but exam questions often test them by asking for exact numbers of protons, neutrons and electrons. In this lesson you will learn how atomic number, mass number and ionic charge control those numbers, and why isotopes are still atoms of the same element.
2.1.1c-e - Relative mass and mass spectrometryAtoms are far too small to weigh one by one in grams, so chemists compare their masses on a relative scale. In this lesson you will learn the carbon-12 mass scale, how isotope data from mass spectrometry is used to calculate relative atomic mass, and when to use the terms relative molecular mass...
2.1.2 - Compounds, formulae and equationsChemical formulae and equations are the shorthand language used through the rest of chemistry. In this lesson you will learn how ionic charges determine formulae, how to balance equations without changing formulae, and how to write ionic equations that show only the particles that actually react.
2.1.3a - The mole and chemical amountChemists need a way to count particles that are far too small to count one by one. The amount of substance, measured in moles, is the counting quantity that connects particles, mass and gas volume. In this lesson you will learn the exact language and one-step conversions that later mole calculati...
2.1.3b-d - Empirical, molecular and hydrated formulaeA chemical formula is a ratio statement. In this lesson you will learn how composition data turns into an empirical formula, how relative molecular mass can scale that into a molecular formula, and how water of crystallisation is handled in hydrated salts. The common thread is simple but powerful...
2.1.3e,g - Reacting masses, concentrations and stoichiometryChemists use amount of substance, measured in mol, as the bridge between particles and measurable quantities. In this lesson you will use mass, gas volume, and solution concentration to find amounts in mol, then use balanced equations to link the amounts of different substances in a reaction. Thi...
2.1.3f - The ideal gas equationGases are often measured by their pressure, volume and temperature rather than by direct weighing. The ideal gas equation links those measurements to the amount of gas in moles, so it is a powerful route from experimental gas data to chemical amount. In this lesson, the main skill is choosing com...
2.1.3h-j - Percentage yield, atom economy and measurementA balanced equation can predict the maximum amount of product a reaction could make, but real experiments rarely give that perfect amount. This lesson teaches two different percentage calculations: percentage yield, which compares the actual product made with the theoretical maximum, and atom eco...
2.1.4a-c - Acids, bases, alkalis and neutralisationAcid-base chemistry starts with a simple particle idea: acids produce hydrogen ions in water, and alkalis produce hydroxide ions in water. In this lesson you will learn the common formulae, how to compare strong and weak acids qualitatively, and how to write balanced neutralisation equations for...
2.1.4d-e - Acid-base titrationsAcid-base titration is a practical method for finding an unknown concentration by reacting a measured volume with a solution whose concentration is known accurately. The chemistry is simple neutralisation, but the result is only trustworthy if the volumes, standard solution and mole-ratio calcula...
2.1.5a-c - Oxidation numbers and redox nomenclatureOxidation numbers are a bookkeeping system for tracking electrons in formulae, compounds and ions. In this lesson, the focus is not yet on full redox reactions. You will learn the rules for assigning oxidation numbers, how to use them to write formulae, and how Roman numerals make names such as i...
2.1.5d-f - Redox reactions and electron transferRedox reactions are reactions where electrons are transferred. In this lesson you will connect the electron-transfer definition to oxidation-number changes, write full equations for metals reacting with acids, and interpret unfamiliar redox equations by tracking what loses and gains electrons.
2.2 - Electrons, bonding and structure
2.2.1 - Electron structureElectrons are not arranged around a nucleus as neat circular tracks. In this lesson you will build the model used in A-level chemistry: shells contain sub-shells, sub-shells contain orbitals, and electron configurations record which orbitals are occupied. The aim is practical: by the end, you sho...
2.2.2a-c - Ionic bonding and giant ionic latticesIonic bonding explains how many metal and non-metal elements form compounds with high melting points, solid crystal structures and state-dependent electrical conductivity. In this lesson you will build the model from ion formation to dot-and-cross diagrams, then use the giant ionic lattice model...
2.2.2d-f - Covalent bonding and dot-and-cross diagramsCovalent bonding is the bonding model used for many molecules and molecular ions. In this lesson you will define a covalent bond precisely, construct dot-and-cross diagrams for single, multiple and coordinate bonds, and use average bond enthalpy as a qualitative measure of covalent bond strength....
2.2.2g-h - Shapes of simple molecules and ionsMolecules and ions are not flat lists of atoms. Their bonds point in three dimensions because electron pairs around a central atom repel each other and settle as far apart as possible. In this lesson you will use that electron-pair-repulsion model to predict the named OCR shapes, bond angles and...
2.2.2i-j - Electronegativity, bond polarity and molecular dipolesElectronegativity explains why a covalent bond can have a slightly negative end and a slightly positive end. In this lesson, you will learn how to interpret Pauling electronegativity values, how a polar bond forms, and why molecular shape decides whether a molecule has an overall dipole.
2.2.2k-l - Intermolecular forces and hydrogen bondingMolecules can be covalently bonded inside themselves and still attract neighbouring molecules. This lesson builds the three intermolecular-force models you need here: induced dipole-dipole interactions, permanent dipole-dipole interactions and hydrogen bonding. The aim is to name each interaction...
2.2.2m-o - Water, simple molecular lattices and propertiesWater is a small covalent molecule, but its physical properties are not what a simple "small molecule" prediction would suggest. In this lesson you will use hydrogen bonding and simple molecular lattice models to explain why ice floats, why water has relatively high melting and boiling points, an...
Periodic table and energy
3.1 - The periodic table
3.1.1a-c - Periodic table, ionisation energy and electron configurationThe periodic table is more than a list of element symbols. It is a map built from atomic number, electron configuration and repeated chemical behaviour. In this lesson you will connect the layout of the table to Period 2 and Period 3 electron configurations, then use first and successive ionisati...
3.1.1d-g - Giant lattices and melting point trendsElements in the same period can have very different melting points because their particles are arranged and bonded in different ways. In this lesson you will connect metallic bonding, giant covalent lattices and simple molecular lattices to melting point, boiling point, solubility and electrical...
3.2 - Physical chemistry
Core organic chemistry
4.1 - Basic concepts and hydrocarbons
4.2 - Alcohols, haloalkanes and analysis
Physical chemistry and transition elements
5.1 - Rates, equilibrium and pH
5.2 - Energy
5.3 - Transition elements
Organic chemistry and analysis
6.1 - Aromatic compounds, carbonyls and acids
6.2 - Nitrogen compounds, polymers and synthesis
6.3 - Analysis