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Term Definition Relevant Topics
Activation Energy Activation energy is the minimum energy required for reactants to undergo a chemical reaction. It can be lowered by using a catalyst. Thermochemistry
Anion A negatively charged ion. Anions are attracted to the anode (positive electrode) during electrolysis. Electrolysis
Anode The positive electrode. Electrolysis
Bond Energy Bond energy is the amount of energy required to break one mole of a stated bond, measured in kJ/mol. It can be used to calculate ΔH for a reaction. Thermochemistry
Cathode The negative electrode. Electrolysis
Cation A positively charged ion. Cations are attracted to the cathode (negative electrode) during electrolysis. Electrolysis
Compound Two or more elements that are chemically joined. Structure & Bonding
Covalent Bond A shared pair of electrons. Structure & Bonding
Covalent Bonding The electrostatic forces of attraction between a shared pair of electrons and common nuclei. Structure & Bonding
Electrode A solid electrical conductor that connects the power source to the electrolyte. Graphite is a common electrode material as it conducts electricity and is chemically inert. Electrolysis
Electrolysis Chemical change caused by passing an electric current through an electrolyte. Electrolysis
Electrolyte A solution or molten substance that conducts electricity. When a current is passed through an electrolyte, electrolysis takes place. Electrolysis
Element A chemical made of only one type of atom. Structure & Bonding
Empirical Formula The empirical formula of a compound is the simplest positive integer (whole number) ratio of atoms of each element in that compound. Moles
Endothermic Reaction An endothermic reaction is one which takes in energy from the surroundings, usually in the form of heat and usually shown by a fall in temperature. Thermochemistry
Exothermic Reaction An exothermic reaction is one which gives out energy to the surroundings, usually in the form of heat and usually shown by a rise in temperature. Thermochemistry
Ion A charged particle that has lost or gained electrons. Structure & Bonding
Ion Migration The movement of ions from the electrolyte to the electrodes (anode and cathode) when an electrical current is passed through it. Electrolysis
Ionic Bonding The electrostatic forces of attraction which hold positive and negative ions together in an ionic lattice. Structure & Bonding
Isotope Isotopes are atoms that have the same number of protons but different numbers of neutrons. They consequently have the same atomic number, but differ in mass number. Moles
Lattice A regular, repeating, giant structure. Structure & Bonding
Metallic Bonding The electrostatic forces of attraction which hold positive ions and delocalised electrons together in a metallic lattice. Structure & Bonding
Mixture A material made up of two or more substances physically combined, but not chemically bonded together. Structure & Bonding
Mole A mole is the unit of 'amount of substance' (just as the gram is the unit of mass). 1 mole is the amount of substance that contains 6 x 1023 particles of the substance. It provides the link between the mass of a substance and the number of particles it contains. 1 mole of any particle has a mass equal to its Ar, in grams. Moles
Molecule Two or more atoms bonded covalently. Structure & Bonding
REDOX Reaction A reaction in which both oxidation and reduction take place. Electrolysis
Relative Atomic Mass, Ar The relative atomic mass is the average mass of an atom of an element compared to 1/12th the mass of a carbon-12 atom, taking into account the proportion of each isotope of the element present. Moles
Relative Molecular Mass / Relative Formula Mass, Mr The relative molecular mass is simply the sum of the relative atomic masses of the compound (or element, e.g. O2 = 2 x 16 = 32). Moles
Salt An ionic compound. Structure & Bonding

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