OCR GCSE Combined Science A key terms

An atom of an element with a particular number of neutrons. Isotopes of the same element have the same number of protons but different numbers of neutrons.

A system of chemical naming based on conventions agreed by the International Union of Pure and Applied Chemistry, allowing substances to be identified consistently.

A graph showing how the current through a component changes with the potential difference across it.

In vitro fertilisation: a fertility treatment in which eggs are fertilised with sperm outside the body and an embryo is then transferred into the uterus.

The SI unit of energy and work done. One joule is the work done by a force of one newton acting through one metre along its line of action.

A unit of energy equal to the energy transferred by a power of 1 kW sustained for 1 hour. $1\text{ kWh}=3.6\times10^6\text{ J}$.

The energy an object has because it is moving.

The energy store associated with an object's motion.

A site where waste is buried, using land that could otherwise have another purpose.

A regular, repeating three-dimensional arrangement of particles in a solid.

A light-dependent resistor whose resistance decreases as the light intensity falling on it increases.

A solution containing dissolved substances removed from a solid; in bioleaching, it contains metal ions.

The rule that, when conditions change in a system at equilibrium, the equilibrium shifts in the direction that opposes the change.

Luteinising hormone: a hormone that triggers ovulation, the release of a mature egg from an ovary.

An assessment of a product’s environmental impacts from obtaining raw materials through manufacture, use and disposal or recycling, including relevant transport.

An assessment of a product’s environmental impacts throughout its lifetime, from obtaining raw materials to final disposal.

A resistor whose resistance decreases as the light intensity falling on it increases.

An electronic timing device that detects when an object interrupts a light beam.

The amount of light energy reaching a given area each second.

An instrument that uses visible light and lenses to produce a magnified image of a specimen.

A strong, stiff, waterproof material that thickens xylem cell walls.

A sedimentary rock mainly made of calcium carbonate, $\mathrm{CaCO_3}$, which stores carbon in the Earth’s crust.

An aqueous solution of calcium hydroxide that turns milky or cloudy when carbon dioxide is bubbled through it.

An environmental factor that restricts the rate of a process because it is in short supply or at an unsuitable level.

The reactant that is completely used up first and therefore determines the maximum amount of product that can form.

The point beyond which force and extension are no longer directly proportional.

A circuit component whose current–potential difference graph is a straight line over the range being considered.