Every key term, with its definition and a picture where one helps. Tap a bold word in the notes to see it there too.
323 terms
A substance that produces hydrogen ions (H⁺) when dissolved in water.
Notes: Reactions of acids · Making soluble salts · pH, neutralisation and strong and weak acids · Alcohols · Carboxylic acids and esters · Synthetic polymers · Identifying negative ions · NPK fertilisers
Rain made acidic by dissolved sulfur dioxide and oxides of nitrogen.
Notes: Atmospheric pollutants
The minimum amount of energy that particles need to collide with in order to react.
Notes: Reaction profiles · Factors affecting rate · Catalysts
Joining many alkene monomers through their double bonds to form a polymer as the only product.
Notes: Synthetic polymers
A reaction where atoms add across a C=C double bond, forming a single product.
Notes: Reactions of alkenes
A base that dissolves in water, producing hydroxide ions (OH⁻).
Notes: Reactions of acids · pH, neutralisation and strong and weak acids
The reactive metals in group 1, which each have one electron in their outer shell.
Notes: Groups 0, 1 and 7
A saturated hydrocarbon with only single bonds; general formula CₙH₂ₙ₊₂.
An unsaturated hydrocarbon with a C=C double bond; general formula CₙH₂ₙ.
Notes: Cracking and alkenes · Synthetic polymers
A mixture of a metal with at least one other element, usually another metal; harder than the pure metal.
Notes: Metallic bonding and alloys · Purity and formulations · Alloys, ceramics, polymers and composites
A small, positively charged particle. A few bounced back off thin gold foil in the scattering experiment, showing that atoms have a tiny, positive nucleus.
Firing alpha particles at gold foil; the few that were deflected showed atoms have a small, positive, dense nucleus.
A monomer with an amine group and a carboxylic acid group; amino acids join to make proteins.
Notes: Natural polymers
NH₃: a gas made in the Haber process and used to make fertilisers.
Notes: Changing the position of equilibrium · The Haber process · NPK fertilisers
Breakdown of organic matter by bacteria without oxygen, producing biogas.
Notes: Waste water treatment
The positive electrode, which attracts negative ions.
Notes: Electrolysis of molten compounds · Electrolysis of aqueous solutions · Chemical cells and fuel cells
A solution in which water is the solvent; it contains H⁺ and OH⁻ ions from the water.
The layer of gases surrounding the Earth.
Notes: The Earth's atmosphere · The Haber process
The smallest part of an element that can exist.
Notes: Atoms, elements and compounds · Groups 0, 1 and 7 · Crude oil and alkanes
The percentage of the total mass of reactants that ends up in the desired product.
Notes: Yield and atom economy
The number of protons in an atom.
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.
Notes: Gas volumes
A symbol equation with the same number of each type of atom on both sides.
The numbers in front of formulae in an equation; they give the mole ratio.
A substance that neutralises an acid to form a salt and water, such as a metal oxide or hydroxide.
Notes: Reactions of acids · Natural polymers
Using bacteria to produce solutions (leachates) containing metal compounds from low-grade ores.
The temperature at which a liquid turns into a gas (and a gas condenses into a liquid).
Notes: Mixtures and separation · Groups 0, 1 and 7 · Ionic bonding · Covalent bonding · Metallic bonding and alloys · States of matter · Polymers and giant covalent structures · Fractional distillation and combustion
Glass made from sand and boron trioxide. It melts at a higher temperature than soda-lime glass, so it's used for laboratory glassware.
An alloy of copper and zinc, harder than pure copper; used for water taps and door fittings.
An orange solution that turns colourless when shaken with an alkene.
Notes: Cracking and alkenes · Reactions of alkenes
An alloy of copper and tin, harder than pure copper; used for statues and decorative objects.
The first fullerene discovered: a hollow, ball-shaped molecule of 60 carbon atoms.
Notes: Carbon structures
A long glass tube with a tap and a scale, used to add a measured volume of solution a little at a time, as in a titration.
Notes: Titrations
A substance made in a reaction alongside the desired product.
Notes: Yield and atom economy
A graph of instrument readings for known concentrations, used to find an unknown concentration.
Notes: Instrumental analysis
A measure of gold purity: 24 carat is pure gold, 18 carat is 75% gold.
Collecting carbon dioxide from places like power stations and storing it, e.g. underground.
Notes: Carbon footprint
CO₂, a gas made when fuels burn and in respiration; the main greenhouse gas from human activity. It turns limewater milky.
Notes: Reactions of acids · Electrolysis of molten compounds · Fractional distillation and combustion · Alcohols · Tests for gases · The Earth's atmosphere · Greenhouse gases and climate change
The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
Notes: Carbon footprint
CO, a toxic gas with no colour or smell, made when fuels burn without enough oxygen.
Notes: Fractional distillation and combustion · Atmospheric pollutants
A cylindrical fullerene with a very high length to diameter ratio; strong and conducts electricity.
Notes: Carbon structures
Causing no overall increase in the amount of greenhouse gases in the atmosphere.
Notes: Carbon footprint
Balancing out greenhouse gas emissions by actions that remove them, such as planting trees.
Notes: Carbon footprint
A compound with the –COOH functional group, such as ethanoic acid.
Notes: Alcohols · Carboxylic acids and esters · Natural polymers
A substance that speeds up a reaction without being used up, by providing a pathway with a lower activation energy.
Notes: Transition metals · Carbon structures · Nanoscience · Reaction profiles · Factors affecting rate · Catalysts · Changing the position of equilibrium · Cracking and alkenes · Carboxylic acids and esters · The Haber process
A device in a car's exhaust that uses a catalyst to turn harmful gases, such as oxides of nitrogen, into less harmful ones.
Notes: Atmospheric pollutants
The negative electrode, which attracts positive ions.
Notes: Electrolysis of molten compounds · Electrolysis of aqueous solutions · Chemical cells and fuel cells
A hard, brittle material such as pottery or brick, made by heating clay.
A device in which chemical reactions produce a voltage.
Separating the substances in a mixture by how far a solvent (the mobile phase) carries each one through paper (the stationary phase).
Notes: Mixtures and separation · Chromatography
A system where no substances can get in or out.
Notes: Conservation of mass and relative formula mass · Reversible reactions and equilibrium
Particles react only when they collide with at least the activation energy.
Notes: Factors affecting rate
Burning in plenty of oxygen, producing carbon dioxide and water.
A material made of a reinforcement held in a matrix, with better properties than either alone.
Notes: Carbon structures · Alloys, ceramics, polymers and composites
Two or more elements chemically combined in fixed proportions.
Notes: Atoms, elements and compounds · Transition metals · Electrolysis of molten compounds · Purity and formulations · The Earth's atmosphere
Conditions chosen to balance yield, rate, cost and safety, rather than to maximise any one of them.
Notes: The Haber process
The amount of solute dissolved in a given volume of solution, e.g. in g/dm³ or mol/dm³.
Notes: Concentration of solutions · pH, neutralisation and strong and weak acids · Titrations · Factors affecting rate · Reversible reactions and equilibrium · Carboxylic acids and esters · Instrumental analysis
Joining monomers with two functional groups each, giving off a small molecule such as water at each link.
Notes: Synthetic polymers · Natural polymers
A cooled tube that turns a vapour back into a liquid, used in distillation.
Notes: Mixtures and separation
No atoms are lost or made in a reaction, so the total mass of reactants equals the total mass of products.
An industrial process that runs all the time, rather than in separate batches.
Notes: NPK fertilisers
The destruction of a material by chemical reactions with substances in its environment.
Notes: Corrosion and its prevention · Alloys, ceramics, polymers and composites
A shared pair of electrons between two atoms.
Notes: Groups 0, 1 and 7 · Ionic bonding · Covalent bonding · Polymers and giant covalent structures · Carbon structures
Breaking long-chain hydrocarbons into shorter, more useful alkanes and alkenes.
Notes: Cracking and alkenes
A bond joining one polymer chain to another. Cross-links stop thermosetting polymers from melting when they're heated.
A finite mixture of hydrocarbons formed from the remains of ancient biomass.
Notes: Crude oil and alkanes · The Earth's atmosphere · Earth's resources and sustainability · Life cycle assessment and recycling
A compound added to aluminium oxide to lower its melting point, reducing the energy needed for electrolysis.
Forming crystals of a solute by evaporating some of the solvent and leaving the solution to cool.
Notes: Mixtures and separation · Making soluble salts · NPK fertilisers
Electrons that are not tied to one atom and are free to move through a structure.
How much mass a material has for a given volume.
Notes: Groups 0, 1 and 7 · Transition metals · Alloys, ceramics, polymers and composites
Removing dissolved salts from sea water, by distillation or reverse osmosis.
Notes: Potable water · Waste water treatment
A form of carbon where each atom forms four covalent bonds; very hard, with a very high melting point.
Notes: Polymers and giant covalent structures · Carbon structures
Having a small amount of solute dissolved in a given volume of solution.
A reaction where a more reactive metal takes the place of a less reactive metal in a compound.
Notes: Reactivity of metals · Redox and ionic equations · Alternative methods of extracting metals
A reaction where a more reactive element takes the place of a less reactive one in a compound.
Notes: Groups 0, 1 and 7
A drawing of a molecule showing every atom and every bond as a line.
Notes: Bond energies · Crude oil and alkanes
Cubic decimetre: 1000 cm³, or one litre.
Notes: Concentration of solutions · Gas volumes · Titrations
Deoxyribonucleic acid: a natural polymer of two strands in a double helix that carries genetic instructions.
Notes: Natural polymers
A diagram showing the electrons of different atoms as dots and crosses, to show how they bond.
Notes: Ionic bonding
Two shared pairs of electrons between the same two atoms, as in O₂.
Notes: Covalent bonding · Cracking and alkenes · Reactions of alkenes
The state in a closed system where the forward and reverse reactions happen at the same rate, so concentrations stay constant.
A conductor, usually a metal or graphite rod, that carries the current into or out of the electrolyte in electrolysis or a cell.
Notes: Electrolysis of molten compounds · Electrolysis of aqueous solutions · Chemical cells and fuel cells
Breaking down an ionic compound, molten or in solution, using electricity.
Notes: Ionic bonding · Reactivity of metals · Electrolysis of molten compounds · Alternative methods of extracting metals
A molten or dissolved ionic compound that conducts electricity.
Notes: Electrolysis of molten compounds · Chemical cells and fuel cells
A particle in a shell around the nucleus with a very small mass and a charge of −1.
Notes: Development of the atomic model · Atomic structure and isotopes · The periodic table · Groups 0, 1 and 7 · Covalent bonding · Carbon structures · Redox and ionic equations
A fixed energy level, at a set distance from the nucleus, where electrons are found.
Notes: Development of the atomic model · The periodic table · Groups 0, 1 and 7 · Ionic bonding · Covalent bonding
How an atom's electrons are arranged in shells, e.g. 2,8,1 for sodium.
The force that pulls oppositely charged particles together, such as the positive and negative ions in an ionic compound.
Notes: Ionic bonding · Metallic bonding and alloys
A substance made of only one type of atom.
Notes: Atoms, elements and compounds · Atomic structure and isotopes
The point in a titration where the indicator changes colour, showing the reaction is complete.
Notes: Titrations
A reaction that takes in energy from the surroundings, so the temperature falls.
Notes: Exothermic and endothermic reactions · Bond energies · Reversible reactions and equilibrium · Changing the position of equilibrium
The overall energy transferred in a reaction: negative if exothermic, positive if endothermic.
Notes: Bond energies
The scientist who led the alpha particle scattering experiment and concluded that an atom's mass and positive charge are in a tiny nucleus: the nuclear model.
A compound with the –COO– functional group, made from a carboxylic acid and an alcohol.
Notes: Carboxylic acids and esters
More than is needed to react, so some is left over.
A reaction that transfers energy to the surroundings, so the temperature rises.
Notes: Exothermic and endothermic reactions · Bond energies · Reversible reactions and equilibrium · Changing the position of equilibrium · Fractional distillation and combustion · The Haber process
A test result that wrongly shows a substance is present.
Notes: Identifying negative ions
Making ethanol and carbon dioxide from sugar using yeast, without oxygen.
Notes: Alcohols
A substance added to soil to supply the elements plants need to grow, mainly nitrogen, phosphorus and potassium.
Notes: Purity and formulations · Waste water treatment · The Haber process
The liquid that passes through the filter paper.
Separating an insoluble solid from a liquid by passing it through filter paper.
Notes: Mixtures and separation · Making soluble salts · Potable water
A resource that is being used up faster than it can be replaced, so it will run out.
Notes: Crude oil and alkanes · Earth's resources and sustainability
An instrumental method that analyses the light from a sample in a flame to identify metal ions and their concentrations.
Notes: Instrumental analysis
Heating a sample in a flame and using the colour to identify the metal ion in it.
A mixture designed as a useful product, with each component in a measured quantity for a particular purpose.
Notes: Purity and formulations · NPK fertilisers
The reaction from left to right in an equation, turning reactants into products.
A fuel formed over millions of years from the remains of ancient living things: coal, crude oil or natural gas.
Notes: The Earth's atmosphere · Greenhouse gases and climate change
A group of hydrocarbons with similar numbers of carbon atoms and similar boiling points.
Separating a mixture of liquids that have different boiling points.
Notes: Mixtures and separation · Fractional distillation and combustion
A tall column, hot at the bottom and cooler at the top, in which the fractions of crude oil condense at different heights.
Notes: Mixtures and separation · Fractional distillation and combustion
How often particles collide, e.g. the number of collisions per second.
Notes: Factors affecting rate
Water with low levels of dissolved salts, such as rain, rivers and groundwater.
Notes: Potable water · Waste water treatment
A cell supplied with a fuel and oxygen, in which the fuel is oxidised to produce a voltage.
A molecule of carbon atoms with a hollow shape, such as Buckminsterfullerene (C₆₀).
Notes: Carbon structures
The group of atoms in a molecule that determines how it reacts.
Notes: Reactions of alkenes · Alcohols · Synthetic polymers · Natural polymers
Coating iron with zinc, which acts as a barrier and as sacrificial protection.
Notes: Corrosion and its prevention
A syringe used to collect a gas and measure its volume, for example to follow the rate of a reaction.
Notes: Measuring rates of reaction
A formula that fits every member of a homologous series, such as CₙH₂ₙ₊₂ for the alkanes.
Notes: Crude oil and alkanes
A huge network of atoms all joined by strong covalent bonds, such as diamond or silicon dioxide.
Notes: Covalent bonding · Polymers and giant covalent structures
A regular 3D arrangement of oppositely charged ions held together by strong electrostatic forces in all directions.
Notes: Ionic bonding
A huge network of atoms or ions held in a regular arrangement by strong bonds, such as diamond or sodium chloride.
Notes: Ionic bonding · Metallic bonding and alloys
Long-term changes to the Earth's climate, including rising average temperatures, caused by more greenhouse gases.
A reduction in the sunlight reaching the Earth's surface, caused by particulates in the air.
Notes: Atmospheric pollutants
A wooden splint with its flame blown out but still glowing; it relights in oxygen.
Notes: Tests for gases
The steepness of a line on a graph: the change up divided by the change across.
Notes: Measuring rates of reaction
A single layer of graphite, one atom thick; strong, light and conducts electricity.
Notes: Carbon structures
A form of carbon in layers of hexagons, with one delocalised electron per atom; soft and conducts electricity.
Notes: Polymers and giant covalent structures · Carbon structures · Electrolysis of molten compounds · Electrolysis of aqueous solutions
The warming of the Earth caused by greenhouse gases absorbing and re-emitting infrared radiation.
A gas, such as carbon dioxide, methane or water vapour, that absorbs infrared radiation and keeps the Earth warm.
Notes: Greenhouse gases and climate change · Carbon footprint
A column of the periodic table; its elements have the same number of outer electrons and similar properties.
Notes: The periodic table · Groups 0, 1 and 7
The industrial process that makes ammonia from nitrogen and hydrogen using an iron catalyst.
Notes: Changing the position of equilibrium · The Haber process
An equation showing the electrons lost or gained by one substance in a redox reaction.
Notes: Redox and ionic equations · Electrolysis of aqueous solutions
A negative ion of a group 7 element, such as Cl⁻, Br⁻ or I⁻.
Notes: Groups 0, 1 and 7 · Electrolysis of aqueous solutions · Identifying negative ions
The non-metals in group 7, which each have seven electrons in their outer shell.
Notes: Groups 0, 1 and 7 · Electrolysis of aqueous solutions · Reactions of alkenes
A form of poly(ethene) made with a different catalyst and conditions from LDPE, giving a stronger, more rigid plastic used for bottles and pipes.
A family of compounds with the same general formula and similar chemical properties.
Notes: Crude oil and alkanes
Containing water as part of a compound's crystals.
Adding water (steam) across a C=C double bond, using a catalyst, to make an alcohol.
Notes: Reactions of alkenes
Adding hydrogen across a C=C double bond, using a catalyst, to make an alkane.
Notes: Reactions of alkenes
More than enough of a reactant, so some is left over when the reaction stops.
Notes: Reacting masses and limiting reactants · Making soluble salts
Burning without enough oxygen, producing carbon monoxide and/or soot as well as water.
Notes: Fractional distillation and combustion · Atmospheric pollutants
A substance that changes colour depending on whether a solution is acidic or alkaline.
Notes: pH, neutralisation and strong and weak acids · Titrations
An electrode, such as graphite, that does not react during electrolysis.
A way of analysing substances using machines, often accurate, sensitive and rapid.
Notes: Instrumental analysis
A material, such as polystyrene, that reduces the transfer of energy as heat.
The weak forces of attraction between separate molecules.
Notes: Covalent bonding · Polymers and giant covalent structures
A charged particle formed when an atom loses or gains electrons.
Notes: Transition metals · Ionic bonding · Reactions of acids · pH, neutralisation and strong and weak acids · Identifying negative ions
The strong electrostatic attraction between oppositely charged ions.
Notes: Groups 0, 1 and 7 · Ionic bonding
An equation showing only the ions and atoms that change in a reaction.
Notes: Redox and ionic equations
Atoms of the same element with the same number of protons but different numbers of neutrons.
The scientist who discovered the electron in 1897, which led to the plum pudding model of the atom.
The scientist whose experiments, about 20 years after the nucleus was accepted, gave the evidence for neutrons in the nucleus.
A scientist who, in the early 1800s, described atoms as tiny solid spheres that can't be divided.
A form of poly(ethene) made with a different catalyst and conditions from HDPE, giving a flexible plastic used for carrier bags.
If the conditions of a system at equilibrium change, the system responds to counteract the change.
The solution of metal compounds produced by bioleaching.
An assessment of the environmental impact of a product at each stage of its life.
A sedimentary rock made mostly of calcium carbonate, formed from the shells and skeletons of sea creatures.
Notes: The Earth's atmosphere · Alloys, ceramics, polymers and composites
Calcium hydroxide solution; it turns milky when carbon dioxide is bubbled through it.
Notes: Reactions of acids · Tests for gases
The reactant that is completely used up, which limits the amount of product made.
The pattern of coloured lines produced by a metal ion; each ion has its own pattern.
Notes: Instrumental analysis
An ore containing only a small amount of metal.
The material in a composite that binds the reinforcement together.
The quantity of reactant used or product formed divided by the time taken.
Notes: Measuring rates of reaction
The temperature at which a solid turns into a liquid (and a liquid freezes into a solid).
Notes: Groups 0, 1 and 7 · Transition metals · States of matter · Carbon structures · Electrolysis of molten compounds
The chemist who, in 1869, arranged the elements with gaps for undiscovered elements and predicted their properties.
Notes: The periodic table
An element that reacts by losing electrons to form positive ions; found on the left of the periodic table.
Notes: The periodic table · Ionic bonding · Metallic bonding and alloys · Redox and ionic equations · Reactions of acids · Electrolysis of molten compounds · Electrolysis of aqueous solutions · Chemical cells and fuel cells · Earth's resources and sustainability
A positive ion formed when a metal atom loses electrons, such as Na⁺ or Cu²⁺.
Notes: Metallic bonding and alloys · Identifying metal ions · Instrumental analysis
The strong electrostatic attraction between positive metal ions and delocalised electrons.
Notes: Ionic bonding · Metallic bonding and alloys
CH₄, the simplest alkane and the main part of natural gas. It's a greenhouse gas, given off by cattle, rice fields and landfill.
Two or more elements or compounds that are not chemically combined.
Notes: Mixtures and separation · Crude oil and alkanes · Purity and formulations · Identifying metal ions · Instrumental analysis
A unit of concentration: moles of solute per cubic decimetre of solution.
Notes: Concentration of solutions · Titrations
The amount of substance containing 6.02 × 10²³ particles; its mass in grams equals the Aᵣ or Mᵣ.
Notes: Moles · Reacting masses and limiting reactants · Concentration of solutions · Gas volumes · Measuring rates of reaction
The ratio of moles of substances in a reaction, given by the numbers in the balanced equation.
Two or more atoms joined together by covalent bonds.
Notes: Groups 0, 1 and 7 · Covalent bonding · Gas volumes · Changing the position of equilibrium · Synthetic polymers · The Haber process
Melted: turned from a solid into a liquid by heating. Ionic compounds conduct electricity when molten because their ions can move.
A small molecule that joins with many others to make a polymer.
Notes: Polymers and giant covalent structures · Synthetic polymers · Alloys, ceramics, polymers and composites
One billionth of a metre (1 × 10⁻⁹ m).
Notes: Atomic structure and isotopes · Nanoscience
A fossil fuel that is mostly methane.
Notes: The Earth's atmosphere · Earth's resources and sustainability · The Haber process
A material obtained from nature or farming, such as wood, cotton or crude oil.
An ion formed when an atom, usually a non-metal, gains electrons.
The reaction between an acid and a base that forms a salt and water.
Notes: Reactions of acids · pH, neutralisation and strong and weak acids
A particle in the nucleus with no charge; discovered by James Chadwick in 1932.
Notes: Development of the atomic model · Atomic structure and isotopes
The scientist who suggested that electrons orbit the nucleus at fixed distances, in shells.
The unreactive elements in group 0, which have full outer shells.
Notes: Groups 0, 1 and 7 · Ionic bonding
An element that does not form positive ions; found on the right of the periodic table.
Notes: The periodic table · Ionic bonding · Covalent bonding · Electrolysis of molten compounds
A formulation of compounds containing nitrogen, phosphorus and potassium to help crops grow.
Notes: NPK fertilisers
A model of the atom with a tiny, positive nucleus containing almost all the mass, surrounded by electrons.
The small centre of an atom, containing protons and neutrons.
Notes: Development of the atomic model · Atomic structure and isotopes · Groups 0, 1 and 7
Oxidation Is Loss of electrons; Reduction Is Gain of electrons.
Notes: Redox and ionic equations
A container that substances can get into or out of, such as an open flask that a gas can escape from.
A rock containing enough of a metal compound for the metal to be worth extracting.
Notes: Reactivity of metals · Alternative methods of extracting metals
The difference in energy between the reactants and the products.
Notes: Reaction profiles · Bond energies
Gain of oxygen (or, at Higher tier, loss of electrons).
Notes: Reactivity of metals · Redox and ionic equations · Electrolysis of molten compounds · Chemical cells and fuel cells · Fractional distillation and combustion · Alcohols
Pollutant gases formed when nitrogen and oxygen react at high temperatures, e.g. in car engines.
Notes: Atmospheric pollutants
A model that explains solids, liquids and gases by the arrangement and movement of their particles.
Notes: States of matter
Tiny solid particles in the air, such as soot (carbon) and unburned hydrocarbons.
Notes: Atmospheric pollutants
Checking of scientific work by other experts before it is published.
The mass of product made as a percentage of the maximum theoretical mass.
Notes: Yield and atom economy
A row of the periodic table; its elements have the same number of electron shells.
Notes: The periodic table
A scale from 0 to 14 showing how acidic or alkaline a solution is; 7 is neutral.
Notes: pH, neutralisation and strong and weak acids · Carboxylic acids and esters · Potable water
A mined rock containing phosphorus; insoluble, so it is treated with acids to make fertilisers.
Notes: NPK fertilisers
The process in algae and plants that uses carbon dioxide and water to make glucose and oxygen.
Notes: The Earth's atmosphere
A change in which no new substance is made, such as melting, boiling or dissolving. It can usually be reversed.
Notes: States of matter
Using plants to absorb metal compounds from soil, then burning them to get ash containing the metal compounds.
A glass tube used to measure out an exact volume of liquid, such as 25.0 cm³, as in a titration.
Notes: Titrations
Thomson's model of the atom as a ball of positive charge with negative electrons embedded in it.
A condensation polymer made from a diol and a dicarboxylic acid, with water given off as each link forms.
Notes: Synthetic polymers
A very large molecule made of many repeating units joined by covalent bonds.
Notes: Covalent bonding · Polymers and giant covalent structures · Cracking and alkenes · Synthetic polymers · Natural polymers
A condensation polymer made from amino acids. Proteins are made of one or more polypeptides.
Notes: Natural polymers
The relative amounts of reactants and products in a mixture at equilibrium.
Notes: Yield and atom economy · Changing the position of equilibrium
An ion formed when an atom, usually a metal, loses electrons.
Notes: The periodic table · Ionic bonding · Reactivity of metals · Electrolysis of molten compounds
Water that is safe to drink, with low levels of dissolved salts and microbes; not chemically pure.
Notes: Potable water
An insoluble solid formed in a solution during a reaction.
The new substances made in a chemical reaction.
Notes: Atoms, elements and compounds · Yield and atom economy · Reaction profiles · Changing the position of equilibrium · Purity and formulations
A natural polymer made of amino acids joined by condensation polymerisation.
Notes: Natural polymers
A particle in the nucleus with a relative mass of 1 and a charge of +1.
Notes: Development of the atomic model · Atomic structure and isotopes · The periodic table
In chemistry, a single element or compound that is not mixed with any other substance.
Notes: Purity and formulations
The largest result minus the smallest result.
Notes: Conservation of mass and relative formula mass · Purity and formulations
How quickly reactants are used up or products are formed.
Notes: Measuring rates of reaction
The substances that react together at the start of a chemical reaction.
Notes: Atoms, elements and compounds · Conservation of mass and relative formula mass · Reaction profiles · Changing the position of equilibrium
The route from reactants to products: the energy path shown on a reaction profile, or the series of reactions used to make a product.
Notes: Yield and atom economy · Catalysts
A graph showing how the energy changes as reactants turn into products.
Notes: Reaction profiles
A list of metals in order of how reactive they are, from most to least reactive.
Notes: Reactivity of metals
A substance added to a sample to test for or cause a reaction.
Notes: Identifying negative ions
Processing used materials so they can be made into new products.
A reaction in which oxidation and reduction happen at the same time.
Notes: Redox and ionic equations
Loss of oxygen (or, at Higher tier, gain of electrons).
Notes: Reactivity of metals · Redox and ionic equations · Electrolysis of molten compounds · Chemical cells and fuel cells
The average mass of an element's atoms, taking the abundance of each isotope into account.
Notes: Atomic structure and isotopes · Conservation of mass and relative formula mass · Moles
The sum of the relative atomic masses of all the atoms in a formula.
A resource that can be replaced as fast as it is used.
The part of a polymer that repeats along the chain, drawn in brackets with n.
Notes: Synthetic polymers
A way of desalinating water by pushing salty water through a membrane that lets water through but not the dissolved salts.
Notes: Potable water
In a reversible reaction, the reaction in which the products react to form the original reactants again.
A reaction where the products can react to form the original reactants again, shown by ⇌.
Notes: Yield and atom economy · Reversible reactions and equilibrium · The Haber process
Distance moved by a substance ÷ distance moved by the solvent; used to identify substances.
Notes: Chromatography
The corrosion of iron or steel, which needs both oxygen and water.
Notes: Corrosion and its prevention
Attaching a more reactive metal to iron so that it corrodes instead of the iron.
Notes: Corrosion and its prevention
A compound formed when the hydrogen in an acid is replaced by a metal.
Notes: Reactions of acids · Waste water treatment · NPK fertilisers
The first stage of sewage treatment, which removes large objects, such as rags and plastics, and grit.
Notes: Waste water treatment
Rock formed from layers of sediment, such as limestone, which can lock up carbon.
Notes: The Earth's atmosphere
A stage of sewage treatment in which solids settle out, giving sewage sludge at the bottom and liquid effluent above it.
Notes: Waste water treatment
Waste water from homes, containing organic matter and harmful microbes.
Notes: Waste water treatment
Melting at one specific temperature, a sign that a substance is pure.
Notes: Purity and formulations
Inner electron shells reducing the attraction between the nucleus and the outer electrons.
Notes: Groups 0, 1 and 7
A giant covalent compound (SiO₂), found in sand, with a very high melting point.
The reagent used to test for halide ions; it forms coloured precipitates with them.
Notes: Identifying negative ions
Separating a liquid from a solution by boiling it off and condensing the vapour.
Notes: Mixtures and separation · Potable water
The most common glass, made by heating sand, sodium carbonate and limestone; used for windows and bottles.
Able to dissolve in a liquid, such as water.
Notes: Making soluble salts · Chromatography · NPK fertilisers
The substance that dissolves in a solvent to make a solution.
Notes: Concentration of solutions
Ions that are present in a reaction but do not change.
The sound hydrogen makes when it burns with a lit splint.
Notes: Reactions of acids · Tests for gases
Letters in an equation showing each substance's state: (s), (l), (g) or (aq).
Notes: States of matter
The phase that doesn't move in chromatography, such as the paper.
Notes: Chromatography
An alloy of iron with carbon and sometimes other metals.
An acid that is completely ionised in water, such as hydrochloric acid.
A collision with enough energy for the particles to react.
Notes: Factors affecting rate
SO₂, a gas made when fuels containing sulfur burn. It causes acid rain and breathing problems.
Notes: Atmospheric pollutants
The surface area of a solid divided by its volume; higher for smaller pieces.
Notes: Nanoscience · Factors affecting rate
Everything around the reacting chemicals, such as the water they are dissolved in, the container and the air.
Development that meets the needs of people today without harming the ability of future generations to meet theirs.
Notes: Yield and atom economy · Earth's resources and sustainability
An equation that shows a reaction using chemical formulae, such as 2Mg + O₂ → 2MgO.
Made by people using chemical processes, rather than occurring naturally.
A straight line that touches a curve at one point, with the same steepness as the curve there.
Notes: Measuring rates of reaction
Breaking down a compound by heating it, e.g. CaCO₃ → CaO + CO₂.
Notes: Conservation of mass and relative formula mass · Cracking and alkenes
A polymer with cross-links between chains that does not melt when heated.
A polymer with separate chains that melts when heated and can be reshaped.
A method for finding the exact volume of one solution that reacts with a known volume of another.
Notes: Titrations · NPK fertilisers
The block of metals between groups 2 and 3 of the periodic table.
Notes: Transition metals · Catalysts
Three shared pairs of electrons between the same two atoms, as in N₂.
Notes: Covalent bonding
How far a result could be from the true value; estimated as range ÷ 2.
A decision based on opinion about how important something is, rather than on measurement.
How thick a liquid is, and how easily it flows.
Eruptions that released gases such as carbon dioxide, water vapour and nitrogen into the early atmosphere.
Notes: The Earth's atmosphere
The 'push' a cell gives to the electric current; bigger when the metals differ more in reactivity.
Notes: Electrolysis of aqueous solutions · Chemical cells and fuel cells
A container of water kept at a set temperature, used to heat a reaction mixture gently and evenly.
Notes: Making soluble salts
An acid that is only partially ionised in water, such as ethanoic acid.
Notes: pH, neutralisation and strong and weak acids · Carboxylic acids and esters
An equation that shows a reaction using the names of the substances, such as magnesium + oxygen → magnesium oxide.
The amount of product obtained from a reaction.
Notes: Yield and atom economy · Changing the position of equilibrium · The Haber process
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