Edexcel GCSE Chemistry key terms

A substance used at the beginning of a manufacturing process to make a product.

A symbol in brackets showing a substance's physical state: (s), (l), (g) or (aq).

The phase that remains in place as the solvent moves through it; in paper chromatography, it is contained in the paper.

An alloy based on iron that contains carbon.

Resistance to elastic bending or changing shape under a force.

The whole number placed before a formula in a balanced equation; it shows the relative number of moles and, for gases under the same conditions, the relative gas volume.

The quantitative relationship between substances in a chemical reaction, obtained from a balanced equation.

The quantitative proportions in which substances react and are formed in a chemical reaction.

The ability of a material to withstand an applied force or stress without failing.

An acid that completely dissociates into ions in aqueous solution.

A way of grouping substances according to the particles present, their arrangement and the bonding or forces between them.

A shortened representation that shows the order in which atoms or groups are connected, such as $CH_3CH_2OH$.

A particle smaller than an atom, such as a proton, neutron or electron.

The variable written alone on one side of an equation; changing the subject means rearranging the equation to isolate a different variable.

A direct change from solid to gas without becoming liquid.

A small number written after an element symbol or bracket in a chemical formula, showing how many of those atoms or groups are present.

A collision between reactant particles that results in a chemical reaction because the particles collide with sufficient energy.

A word ending added to the main part of a word; in chemical names, endings such as -ide and -ate provide information about composition.

A type of carbohydrate molecule; sugar molecules form the units on which starch is based.

An ion with the formula $\mathrm{SO_4^{2-}}$. It forms a white precipitate with barium ions in an acidified solution.

An acidic gas with the formula SO₂ that dissolves in water and contributes to acid rain.

The area covered by a film, measured in units such as cm² or m².

The exposed surface area of an object divided by its volume.

The total exposed area of an object divided by the space it occupies.

Everything outside the reacting substances that can transfer energy to or from them, such as the solution, container and nearby air.

Able to continue over the long term without exhausting resources or causing unacceptable environmental harm.

The substances and reactions being considered, separated conceptually from their surroundings.

A straight line that touches a curve at the point where its gradient is being estimated.