OCR GCSE Chemistry A key terms

A solution of calcium hydroxide used to test for carbon dioxide.

A weakness or boundary of a model that prevents it from representing or explaining some feature of reality.

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

A chart showing the wavelengths of light emitted by a substance as separate lines or peaks.

The state of a substance that flows and has a fixed volume but no fixed shape, represented by $(l)$.

A chemical used to make otherwise colourless spots visible on a chromatogram.

A scale on which equal changes in the scale value represent multiplication by a constant factor rather than equal additions.

A pair of outer-shell electrons that is not shared in a covalent bond.

Ore containing a relatively small amount of the metal or metal compound wanted.

The size range of objects that can normally be seen and handled directly, rather than individual atoms or molecules.

How many times larger a model is than the real object.

Able to be hammered or pressed into shape without breaking.

The mass of a sample, represented by $m$ and commonly measured in grams in mole calculations.

The total number of protons and neutrons in an atom's nucleus.

An analytical technique that produces a spectrum by detecting ions according to their mass-to-charge ratio.

A chart showing the mass-to-charge ratios of detected ions and their relative abundances.

The mass of an ion divided by the size of its charge; written as m/z.

The change in a measured quantity divided by the time taken over a specified interval.

The change from the solid state to the liquid state when energy is transferred to a substance.

The temperature at which a solid and liquid can coexist as melting or freezing occurs at a given pressure.

The interval from the temperature at which a sample first begins to melt to the temperature at which it has completely melted.

The curved surface of a liquid. For a liquid with a concave surface, read the bottom of the curve.

An element whose atoms typically lose electrons in reactions and form positive ions.

The electrostatic attraction between positive metal ions and delocalised electrons.

An element close to the boundary between metals and non-metals that has some properties associated with each.

One millionth of a metre: $1\text{ μm}=10^{-6}\text{ m}$.

A material containing two or more substances that are not chemically bonded together.

An ion or electron that is free to move through a material and can therefore carry electric charge.