Chemistry for Cambridge IGCSE Coursebook Review

Comprehensive vocabulary flashcards covering States of Matter, Atomic Structure, Bonding, Formulae, Stoichiometry, Electrochemistry, Energetics, Rates, Equilibrium, Redox, and Acids/Bases from the Cambridge IGCSE Chemistry Coursebook.

Matter

Anything that occupies space and has mass.

States of matter

Solid, liquid and gas; the three forms in which any substance can exist depending on the conditions of temperature and pressure.

Fluid

A gas or a liquid which has the ability to flow.

Melting point ($m.p.$)

The temperature at which a solid turns into a liquid; it has the same value as the freezing point. A pure substance has a sharp melting point.

Evaporation

A process occurring at the surface of a liquid involving the change of state from a liquid into a vapour at a temperature below the boiling point.

Boiling

The process of change from liquid to gas at the boiling point of the substance, where gas bubbles form within the body of the liquid.

Boiling point

The temperature at which a liquid boils, occurring when the pressure of the gas created above the liquid equals atmospheric pressure.

Volatile

A term describing a liquid that evaporates easily, typically having a low boiling point due to weak intermolecular forces.

Volatility

The property of how easily a liquid evaporates.

Condensation

The change of a vapour or a gas into a liquid, during which heat is given out to the surroundings.

Pure substance

A single chemical element or compound that melts and boils at definite, precise temperatures.

Lattice

A regular three-dimensional arrangement of atoms, molecules or ions in a crystalline solid.

Atom

The smallest particle of an element that can take part in a chemical reaction.

Kinetic particle theory

A theory that accounts for the bulk properties of the different states of matter in terms of the movement of particles ($atoms$ or $molecules$).

Molecule

A group of atoms held together by covalent bonds.

Intermolecular space

The space between atoms or molecules in a liquid or gas; it is small in a liquid but relatively very large in a gas.

Intermolecular forces

The weak attractive forces that act between molecules.

Exothermic changes

A process or chemical reaction in which heat energy is produced and released to the surroundings; $\Delta H$ has a negative value.

Endothermic changes

A process or chemical reaction that takes in heat from the surroundings; $\Delta H$ has a positive value.

Mixture

Two or more substances mixed together but not chemically combined; they can be separated by physical means.

Solution

Formed when a substance ($solute$) dissolves into another substance ($solvent$).

Solute

The solid substance that has dissolved in a liquid to form a solution.

Solvent

The liquid that dissolves the solid solute to form a solution, such as water or organic solvents.

Suspension

A mixture containing small particles of an insoluble solid or droplets of an insoluble liquid spread throughout a liquid.

Precipitation reaction

A reaction in which an insoluble salt is prepared from solutions of two soluble salts.

Miscible

Two liquids that form a completely uniform mixture when added together.

Alloys

Mixtures of elements, usually metals, designed to have properties useful for a particular purpose.

Saturated solution

A solution that contains as much dissolved solute as possible at a particular temperature.

Concentration

A measure of how much solute is dissolved in a solvent to make a solution.

Diffusion

The process by which different fluids mix as a result of the random motions of their particles.

Porous pot

An unglazed pot that has channels (pores) through which gases can pass.

Element

A substance that cannot be further divided into simpler substances by chemical methods; all atoms of an element contain the same number of protons.

Compound

A substance formed by the chemical combination of two or more elements in fixed proportions.

Electron

A subatomic particle with negligible mass and a relative charge of $-1$, located in shells outside the nucleus.

Proton

A subatomic particle with a relative atomic mass of $1$ and a charge of $+1$ found in the nucleus.

Nucleus

The central region of an atom made up of protons and neutrons.

Neutron

An uncharged subatomic particle present in the nucleus with a mass of $1$ relative to a proton.

Proton number ($Z$)

The number of protons in the nucleus of an atom; also known as the atomic number.

Mass number ($A$)

The total number of protons and neutrons in the nucleus of an atom; also known as the nucleon number.

Relative atomic mass ($A_r$)

The average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly $12$ units.

Isotopes

Atoms of the same element that have the same proton number but a different nucleon number due to different numbers of neutrons.

Electronic configuration

A shorthand method of describing the arrangement of electrons within the electron shells of an atom.

Noble gases

Elements in Group VIII of the Periodic Table which are stable and very unreactive.

Covalent bonding

Chemical bonding formed by the sharing of one or more pairs of electrons between two atoms.

Ionic bonding

A strong electrostatic force of attraction between oppositely charged ions formed by the transfer of electrons.

Cation

A positive ion attracted to the cathode in electrolysis.

Anion

A negative ion attracted to the anode in electrolysis.

Empirical formula

A formula for a compound that shows the simplest ratio of atoms present.

Molecular formula

A formula that shows the actual number of atoms of each element present in one molecule of a compound.

Water of crystallisation

Water included in the structure of certain salts as they crystallise, such as in $CuSO_4 \cdot 5H_2O_{(s)}$.

Stoichiometry

The ratio of the reactants and products in a balanced symbol equation.

Mole

The unit of amount of substance; $1$ mole contains $6.02 \times 10^{23}$ particles and has a mass equal to the relative formula mass in grams.

Molar gas volume

The volume occupied by $1$ mole of any gas, which is $24\,dm^3$ at room temperature and pressure (r.t.p.).

Electrolysis

The breakdown of an ionic compound, molten or in aqueous solution, by the use of electricity.

Anode

The positive electrode in an electrolytic cell at which oxidation (loss of electrons) takes place.

Cathode

The negative electrode in an electrolytic cell at which reduction (gain of electrons) takes place.

Enthalpy change ($\Delta H$)

The heat change during the course of a reaction; negative for exothermic and positive for endothermic reactions.

Activation energy ($E_a$)

The minimum energy required for a collision between reactant particles to result in a chemical reaction.

Catalyst

A substance that increases the rate of a chemical reaction but remains unchanged at the end of the reaction.

Dynamic equilibrium

A state in a closed system where the forward and reverse reactions occur at the same rate, keeping concentrations constant.

Haber process

The industrial manufacture of ammonia ($NH_3$) from nitrogen and hydrogen using an iron catalyst, $450^{\circ}C$, and $20000\,kPa$ pressure.

Contact process

The industrial manufacture of sulfuric acid ($H_2SO_4$) involving the catalytic oxidation of sulfur dioxide using vanadium(V) oxide.

Redox reaction

A reaction involving both reduction and oxidation simultaneously.

Displacement reaction

A reaction in which a more reactive element displaces a less reactive element from a solution of its salt.

Oxidation number

A number given to show whether an element has been oxidised or reduced; in a simple ion, it is the charge on the ion.

Acid

A proton donor that dissolves in water to produce $H^+(aq)$ ions, having a pH below 7.

Base

A proton acceptor that neutralises an acid to produce a salt and water only.

Amphoteric compound

A hydroxide or metal oxide that reacts with both an acid and an alkali to give a salt and water.