IGCSE Chemistry Review Flashcards

These vocabulary flashcards cover all core topics from Chapters 1 through 12, ranging from states of matter and atomic structure to organic chemistry and experimental techniques, as detailed in the lecture notes.

Solids

States of matter with a fixed volume and fixed shape, characterized by high density and particles that vibrate in place while closely packed in a regular pattern.

Liquids

States of matter with a fixed volume that take the shape of their container; particles move and slide past each other and are less dense than solids but more dense than gases.

Gases

States of matter without a fixed volume that take the shape of their container; they have the lowest density, are easily compressed, and have particles that move quickly and randomly.

Boiling

A change of state from liquid to gas occurring at a specific boiling point (b.p.) where heat forms bubbles of gas below the surface of the liquid.

Evaporation

The change from liquid to gas at any temperature occurring only at the surface where high energy particles escape.

Condensation

The process where a gas becomes a liquid at a range of temperatures as particles lose energy and group together.

Kinetic Theory

The theory stating that when a substance is heated, particles absorb thermal energy and convert it to kinetic energy, causing them to vibrate or move more.

Brownian Motion

The random motion of particles suspended in a fluid (liquid or gas) resulting from their collision with the fast-moving molecules in the fluid.

Diffusion

The movement of particles from an area of high concentration to an area of low concentration until they are evenly spread out; it occurs faster in gases and at higher temperatures.

Elements

Substances made up of atoms that contain the same proton number and cannot be split into something simpler.

Compounds

Substances made of two or more elements chemically combined in fixed ratios that cannot be separated by physical methods.

Mixtures

A combination of two or more substances (elements and/or compounds) that are not chemically combined and can be separated by physical methods.

Electronic Configuration

The arrangement of electrons in an atom, often represented by the number of electrons in each shell separated by commas (e.g., 2, 8, 1).

Valence Shell

The outermost occupied electron shell of an atom.

Isotopes

Different atoms of the same element that have the same number of protons but different numbers of neutrons.

Relative Atomic Mass ($A_r$)

The average mass of the isotopes of an element compared to $\frac{1}{12^{th}}$ of the mass of an atom of $^{12}C$.

Nucleus

The center of an atom containing protons and neutrons, where most of the atom's mass is concentrated.

Atomic Number ($Z$)

The number of protons in the nucleus of an atom, identifying its position on the Periodic Table.

Mass Number ($A$)

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

Metallic Bonding

The attraction between positive metal ions and a 'sea' of delocalized electrons in a giant metallic lattice structure.

Ion

An electrically charged atom or group of atoms formed by the loss or gain of electrons to achieve a full outer shell.

Cation

A positively charged ion formed when a metal atom loses electrons.

Anion

A negatively charged ion formed when a non-metal atom gains electrons.

Ionic Bond

A strong electrostatic force of attraction between oppositely charged ions.

Covalent Bond

The bond formed when pairs of electrons are shared between non-metal atoms.

Allotropes

Physically different forms of the same element, such as diamond and graphite for carbon.

Diamond Structure

A giant covalent structure where each carbon atom bonds with 4 other carbons in a tetrahedron, making it hard and an electrical insulator.

Graphite Structure

A giant covalent structure where carbon atoms bond to 3 others in hexagonal layers with one free delocalized electron, allowing it to conduct electricity.

Empirical Formula

The simplest whole number ratio of atoms of each element present in a molecule or formula unit.

Molecular Formula

The formula showing the actual number of atoms of each element present in one molecule of a compound.

Valency

The number of electrons an atom needs to lose or gain to achieve a full outer shell.

Aqueous (aq)

A state symbol indicating that a substance is dissolved in water.

Mole (mol)

The unit of amount of substance that contains $6.02 \times 10^{23}$ particles.

Avogadro's Constant

The number of particles in one mole of a substance, equal to $6.02 \times 10^{23}$.

Molar Gas Volume

The volume occupied by one mole of any gas at room temperature and pressure (R.T.P), which is $24\,dm^3$.

Concentration

The amount of solute in a specific volume of solvent, measured in $g\,dm^{-3}$ or $mol\,dm^{-3}$.

Percentage Yield

A measure of the efficiency of a reaction calculated as $\text{Yield} = \frac{\text{actual yield}}{\text{theoretical yield}} \times 100$.

Percentage Purity

The ratio of the mass of a pure substance to the total mass of the sample, expressed as a percentage.

Electrolysis

The decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current.

Cathode

The negative electrode where cations are reduced during electrolysis.

Anode

The positive electrode where anions are oxidized during electrolysis.

Electrolyte

The liquid or solution that contains ions and is decomposed by electricity during electrolysis.

Electroplating

A process using electrolysis to coat the surface of one metal with another to improve appearance and resistance to corrosion.

Oxidation

A process in which a substance loses electrons, gains oxygen, or increases in oxidation number.

Reduction

A process in which a substance gains electrons, loses oxygen, or decreases in oxidation number.

Exothermic Reaction

A reaction that transfers thermal energy to the surroundings, resulting in a temperature increase ($\Delta H$ is negative).

Endothermic Reaction

A reaction that takes in thermal energy from the surroundings, resulting in a temperature decrease ($\Delta H$ is positive).

Activation Energy ($E_a$)

The minimum amount of energy that colliding particles must have to react.

Enthalpy Change ($\Delta H$)

The transfer of thermal energy during a reaction, calculated as $\text{Energy In} - \text{Energy Out}$.

Collision Theory

The theory that for a reaction to occur, particles must collide with sufficient energy (activation energy) and correct orientation.

Catalyst

A substance that increases the rate of reaction by lowering the activation energy without being used up or changed.

Redox Reaction

A chemical reaction that involves simultaneous oxidation and reduction.

Oxidising Agent

A substance that oxidizes another substance while reducing itself.

Reducing Agent

A substance that reduces another substance while oxidizing itself.

Haber Process

The industrial process used to produce ammonia from nitrogen and hydrogen using an iron catalyst at $450\,^{\circ}C$ and $200\,atm$.

Contact Process

The industrial process for making sulfur trioxide (and eventually sulfuric acid) using a Vanadium(V) oxide ($V_2O_5$) catalyst at $450\,^{\circ}C$.

Acid

A proton donor that forms hydrogen ions ($H^+$) in aqueous solution.

Base

A proton acceptor, often a metal oxide or hydroxide; soluble bases are called alkalis and form hydroxide ions ($OH^-$) in water.

Strong Acid

An acid that is completely dissociated in aqueous solution, such as hydrochloric acid ($HCl$).

Weak Acid

An acid that is only partially dissociated in aqueous solution, such as ethanoic acid ($CH_3COOH$).

Amphoteric Oxide

An oxide that can react with both acids and bases to produce salt and water (e.g., $Al_2O_3$, $ZnO$).

Water of Crystallisation

The water molecules chemically combined in the structure of hydrated crystals, such as the '5' in $CuSO_4 \cdot 5H_2O$.

Alloy

A mixture of a metal with other elements (e.g., brass, stainless steel) designed to be harder and stronger than pure metals.

Reactivity Series

A list of metals in order of their combined tendency to lose electrons and form positive ions.

Galvanising

The process of coating iron with a layer of zinc, which is more reactive and oxidizes first to protect the iron.

Greenhouse Effect

The process where gases like $CO_2$ and methane absorb heat reflected from the Earth's surface and re-emit it, leading to global warming.

Hydrocarbons

Organic compounds that contain only hydrogen and carbon atoms.

Fractional Distillation of Petroleum

The process of separating crude oil into useful fractions based on their boiling points in a fractionating column.

Alkanes

Saturated hydrocarbons containing only single covalent bonds between carbon atoms.

Alkenes

Unsaturated hydrocarbons that contain at least one double carbon-carbon covalent bond ($C=C$).

Cracking

The process of breaking down long-chain alkanes into smaller, more useful molecules like short-chain alkanes and alkenes using heat and a catalyst.

Fermentation

The production of ethanol from aqueous glucose at $25-35\,^{\circ}C$ in the presence of yeast and absence of oxygen.

Solvent

A substance that dissolves a solute to form a solution.

Solute

A substance that is dissolved in a solvent.

Saturated Solution

A solution containing the maximum concentration of a solute dissolved at a specified temperature.

Chromatography

A technique used to separate substances that have different solubilities in a specific solvent.

$R_f$ Value

The ratio of the distance traveled by a substance to the distance traveled by the solvent front in chromatography.