AQA GCSE Chemistry key terms

A reaction that takes in energy from the surroundings, leaving the products at a higher energy level than the reactants.

The point in a titration at which the indicator shows a lasting colour change.

The proportion of the energy supplied to a device or process that is transferred usefully rather than wasted.

A region around the nucleus that electrons with similar energies occupy; also called an electron shell.

The mass represented by a substance in a balanced equation, calculated as its coefficient multiplied by its $M_r$.

The relative amounts of reactants and products present in a system at equilibrium.

The amount or percentage of product present when equilibrium has been reached under stated conditions.

The point at which measured amounts of two solutions have reacted in exactly the ratio given by the balanced equation.

A compound formed when a carboxylic acid reacts with an alcohol, producing water as the other product.

To consider relevant advantages, disadvantages and uncertainties before reaching a judgement supported by evidence.

The change of a liquid into a gas.

A solution containing more of a reagent than is needed to complete the initial reaction.

A reactant present in a greater amount than is needed to react completely with the limiting reactant, so some remains unreacted.

A process that transfers energy to the surroundings.

A reaction that transfers energy to the surroundings, leaving the products at a lower energy level than the reactants.

Obtaining a metal from the compound in which it occurs naturally.

An incorrect positive result caused by something other than the ion being tested for.

A substance used as a starting material to make other chemicals and materials.

The breakdown of sugar by yeast without oxygen, producing ethanol and carbon dioxide.

A substance added to soil to supply nutrients that help plants grow.

The liquid that passes through filter paper during filtration.

The removal of insoluble solid particles by passing water through a filtering material.

Particles with diameters from 100 nm to 2500 nm; the upper limit is 2.5 micrometres.

A natural resource that is used much faster than it forms, so its supply can eventually run out.

An instrumental method that analyses metal ions in a solution using the light emitted when the sample is placed in a flame.

A qualitative test in which a sample is heated in a flame and a characteristic flame colour may reveal the metal ion present.

How easily a substance catches fire and burns.