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Browse key terms and definitions across all GCSE subjects. Search by keyword or filter by subject and exam board.
23,110 key terms
Raw material
A natural material used to manufacture a product, such as a metal, oil or sand.
Raw material
A starting material that is processed to make a usable material, component or product.
Raw material extraction
Obtaining natural resources, such as oil, metal ores or timber, to make materials and products.
Raw materials
The materials used to make products, such as iron for tools or leather for shoes.
Raw materials
The substances obtained and processed to make a product.
Raw value
An original data value, before it has been converted into a standardised score.
Ray
A line showing the direction in which a wave travels.
Ray
A line representing the direction in which a wave travels, with an arrowhead showing that direction.
Ray diagram
A two-dimensional drawing that uses straight, directed lines to represent the paths taken by light.
Reabsorption
The return of a substance from fluid in the kidney to the blood.
Reactant
A substance that is used up in a chemical reaction.
Reactant
A starting substance that is changed during a chemical reaction.
Reactant
A starting substance that undergoes change in a chemical reaction.
Reactant in excess
A reactant supplied in a greater amount than is needed to react completely with the limiting reactant, so some remains.
Reactants
The substances present at the start of a chemical reaction.
Reacting mass
The calculated amount of reactant needed or product formed when the reacting quantities follow a balanced equation.
Reacting-mass ratio
The ratio of the masses of substances that react or form, calculated from a balanced equation and their relative formula masses.
Reaction arrow
The arrow pointing from reactants to products; it can be read as “produces” or “forms”.
Reaction condition
A factor deliberately set or changed during a reaction, such as temperature, concentration, gas pressure or the surface area of a solid.
Reaction conditions
Factors such as temperature and the presence or removal of substances that affect how a reaction proceeds.
Reaction conditions
The physical circumstances in which a reaction takes place, such as temperature.
Reaction force
A force exerted on an object by a surface or support in contact with it.
Reaction mixture
The substances mixed together in which a chemical reaction takes place.
Reaction pathway
The sequence of changes by which reactants are converted into products during a reaction.
Reaction profile
A diagram showing how the energy of a reacting system changes as a reaction proceeds from reactants to products.
Reaction profile
A diagram showing how energy changes as a chemical reaction progresses from reactants to products.
Reaction rate
The amount of a reactant used or product formed per unit time.
Reaction shot
A shot showing a character’s response to an event or another character, which can guide the audience’s interpretation.
Reaction system
The reacting substances being considered when tracking an energy transfer.
Reaction time
The time between a stimulus occurring and a person responding to it.
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