Question | Answer |
Ionisation enthalpy | “the energy needed to remove one mole of electrons from one mole of gaseous atoms to make one mole of gaseous ions – e.g. Na(g) → Na+(g) + e- |
Hydrolysis | reaction with water or reaction with OH- (to make alcohols) |
Nucleophile | “a molecule or negatively charged ion with a lone pair of electrons that it can donate to a positively charged atom to form a covalent bond” |
Enthalpy profile | “a plot of reaction progress against enthalpy” |
Activation enthalpy | “the minimum kinetic energy required by colliding particles before reaction will occur” |
Catalyst | “a substance which speeds up a reaction but can be recovered chemically unchanged at the end. It works by providing an alternative pathway of lower activation enthalpy” |
Homogeneous | “when reactants and catalysts are in the same physical state” |
Heterogeneous | “when reactants and catalysts are in different physical states” |
Dynamic equilibrium | “a reaction when the forward and back reactions are occurring at the same rate. The concentrations of the products and reactants remains constant and it occurs in a closed system” |
Le Chatelier’s principle | “if a system is at equilibrium and a change is made in any of the conditions, then the system responds to counteract the change” |
Homolytic bond fission | “forms radicals” |
Heterolytic bond fission | forms ions |
Elimination reaction | “a small molecule is removed from a larger one leaving an unsaturated molecule” |
Addition polymerisation | “where 2 or more molecules react to form a single larger one” |
Addition reaction | “where 2 or more molecules react to form a single larger one” |
Electrophile | “a positively charged ion or a molecule with a partial positive charge that will be attracted to a negatively charged region and react by accepting a lone pair of electrons to form a covalent bond |
Carbocation | positively charged carbon atom |
Substitution reaction | when one functional group on an organic molecule is substituted for another one. |
Thermoplastic | a polymer which can be repeatedly heated and reshaped |
Thermoset | polymers which contain extensive crosslinking which prevents remoulding even when heated |
Co-polymer | “when more than one monomer is used during an addition polymerisation” |
Electronegativity | “the attraction of an atom for a pair of electrons in a covalent bond” |
Radical | a chemical with an unpaired electron |