OCR GCSE Chemistry A key terms

The number of protons in the nucleus of an atom; it identifies the element.

The distance from the centre of an atom to its outer edge.

The structure of an atom, comprising a central nucleus containing protons and neutrons, with electrons occupying energy levels around it.

A comparison showing the relative numbers of different atoms, written in the same order as their element symbols.

A rate calculated over a time interval rather than at one particular instant.

The fixed number of specified particles per mole, $6.02\times10^{23}\ \mathrm{mol^{-1}}$.

An equation with the same number of atoms of each element on both sides.

A symbol equation containing the same number of atoms of each element on both sides.

An equation containing chemical formulae in which each element has the same number of atoms on both sides.

A model that uses spheres for atoms and sticks for bonds to show how atoms are arranged in three dimensions.

A substance that reacts with an acid to form a salt and water.

The pencil line from which the samples begin moving during chromatography.

The tallest peak in a mass spectrum, assigned a relative abundance of 100.

The same amount of service provided by each product being compared, such as carrying the same number of shopping loads.

Production of a limited quantity before the apparatus is prepared for another run.

A line or smooth curve drawn to represent the overall pattern of experimental results rather than joining every point mechanically.

An ionic compound containing only two different elements, usually a metal and a non-metal.

A biological extraction method in which bacteria help release metal compounds from low-grade ore into a solution.

The change from the liquid state to the gas state throughout a liquid, producing bubbles.

The temperature at which a liquid boils and changes to a gas at a given pressure.

The energy needed to break one mole of a particular type of covalent bond in gaseous substances.

The type of attraction that joins particles and the pattern in which those particles are organised.

The distance between the nuclei of two bonded atoms.

An alloy of copper and zinc.

Describes a material that cracks or breaks rather than deforming substantially when a force is applied.

An alloy of copper and tin.

A property of a material that arises from large numbers of particles acting together, such as malleability or electrical conductivity.