Ocr A Level Chemistry Already Passed

endothermic reaction {Ans: A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings (∆H +ve).}nucleophile {Ans: An atom (or group of atoms) that is attracted to an electron- deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.}energy {Ans: e.g. the second ionisation energy is the energy required to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.}skeletal formula {Ans: A simplified organic formula, with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups.}biodegradable material {Ans: A substance that is broken down naturally in the environment by living organisms.}unsaturated hydrocarbon {Ans: A hydrocarbon containing carbon-to-carbon multiple bonds.}saturated hydrocarbon {Ans: A hydrocarbon with single bonds only.}electronegativity {Ans: A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond.}heterolytic fission {Ans: The breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (+ ion) and