Chemistry key terms

A negatively charged ion formed when an atom gains one or more electrons.

A two-dimensional arrangement of faces that can be folded to make a three-dimensional shape.

The total charge found by combining all the positive and negative charges in a particle.

An equation showing only the ions that undergo chemical change in a reaction.

Having no overall electrical charge because positive and negative charges balance.

A reaction in which an acid reacts with a base. Reactions with metal oxides or hydroxides produce a salt and water; metal carbonates also produce carbon dioxide.

The condition in which the concentrations of hydrogen ions and hydroxide ions are equal; a neutral solution has pH 7.

A solution with pH 7, so it is neither acidic nor alkaline.

A particle with no electrical charge found in an atom's nucleus.

An acid with the formula $\mathrm{HNO_3}$; in aqueous solution it supplies hydrogen ions and nitrate ions.

An oxide of nitrogen with the formula $\mathrm{NO_2}$ that can form when nitrogen monoxide reacts with more oxygen.

An oxide of nitrogen with the formula $\mathrm{NO}$, formed when nitrogen and oxygen react at very high temperatures.

An element in the far-right group of the periodic table whose atoms have a stable, full outer electron shell and are therefore very unreactive.

The arrangement of electrons found in a Group 0 atom, with a complete outer electron shell.

A solvent other than water, such as ethanol or propanone.

Not readily broken down by microorganisms, so it can persist in the environment for a long time.

A system from which matter, including a gas, can enter or leave during a reaction.

A metal that is not iron, such as copper.

A gas that does not burn.

An electrode whose material takes part in the reaction; a copper anode dissolves during electrolysis of copper sulfate solution.

An element that does not react to form positive ions.

A cell designed to be used until a reactant is used up, after which its reaction cannot be usefully reversed by charging.

A resource that is used much faster than natural processes can replace it, so its supply is finite on a human timescale.

A fertiliser containing compounds that supply nitrogen, phosphorus and potassium.

The electrostatic attraction between the positively charged nucleus and a negatively charged electron.

A model in which an atom has a central nucleus containing protons and neutrons, with electrons around it.

A proton or neutron; both are particles found in an atomic nucleus.

One of the four types of monomer that make up DNA polymer chains.

The small central region of an atom in which almost all its mass and its positive charge are concentrated.

A visible or otherwise detectable result of a test, such as a colour change, precipitate or relighting splint.