Chemistry key terms

Climate change resulting from human activities.

An increase in the amount of greenhouse gases in the atmosphere caused by human activity.

The change in the mass measured for part of a reacting system when matter crosses its boundary, even though the total mass of all reactants and products is conserved.

Dissolved in water; shown by the state symbol (aq).

A solution in which an acid is dissolved in water and can provide hydrogen ions, H⁺.

A solution in which a substance is dissolved in water, represented by the state symbol $(aq)$.

A solvent in which water is the solvent or main solvent.

A reasoned case in which evidence and ideas are used to support a conclusion.

The sum of a set of values divided by the number of values.

A condition accepted as true when constructing or using a model, often to simplify the real system.

An ending usually showing that the negative ion contains oxygen bonded to another element, as in nitrate, carbonate or sulfate.

The layer of gases surrounding a planet.

The smallest particle of an element that can take part in chemical reactions, consisting of a nucleus surrounded by electrons.

The percentage of the total relative mass of the reactants that becomes the desired useful product, as shown by a balanced equation.

A proposed description of an atom that can be changed when new evidence is found.

The number of protons in the nucleus of an atom. It identifies the element and determines the number of electrons in a neutral atom.

The approximate distance from the centre of an atom to the extent of its electron cloud.

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

A historical measure of an element’s atomic mass relative to that of another atom; it corresponds broadly to what is now called relative atomic mass.

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

The people for whom a communication is intended, such as specialist scientists, the public or policy-makers.

The change in a measured quantity divided by the time interval over which that change occurred.

The number of specified particles in one mole, with the value $6.02 \times 10^{23}\ \text{mol}^{-1}$.

At the same temperature and pressure, equal volumes of gases contain equal numbers of gas particles.

The use of bacteria to release metal compounds from ores or waste material, commonly producing a solution called a leachate.

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

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

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

The number written before a formula in a balanced equation, showing the reacting ratio of particles or amounts in moles.

A model in which balls represent atoms and sticks represent bonds, making the arrangement of atoms easier to see.