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OCR A LEVEL CHEMISRTY EXAM 2019 WITH 100% CORRECT QUESTIONS AND ANSWERS
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OCR A LEVEL CHEMISRTY EXAM 2019 WITH 100% CORRECT QUESTIONS AND ANSWERS
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OCR A LEVEL CHEMISRTY EXAM 2019 WITH 100% CORRECT QUESTIONS AND ANSWERS mechanism - ANSWER -A sequence of steps showing the path taken by electrons in a reaction. metallic bond - ANSWER -The electrostatic attraction between positive metal ions and delocalised electrons. molar mass, M - ANSWER -The mass mole of a substance. The units of molar mass are g mol -1. molar volume - ANSWER -The volume per mole of a gas. The units of molar volume are dm3 mol -1. At room temperature and pressure the molar volume is approximately 24.0 dm3 mol -1. mole - ANSWER -The amount of any substance containing as many particles as there are carbon atoms in exactly 12 g of the carbon -12 isotope. molecular formula - ANSWER -The number of atoms of each element in a molecule. molecular ion, M+ - ANSWER -The positive ion formed in mass spectrometry when a molecule loses an electron. molecule - ANSWER -A small group of atoms held together by covalent bonds. monomer - ANSWER -A small molecule that combines with many other monomers to form a polymer. nomenclature - ANSWER -A system of naming compounds. nucleophile - ANSWER -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. nucleophilic substitution - ANSWER -A type of substitution reaction in which a nucleophile is attracted to an electron -deficient centre or atom, where it donates a pair of electrons to form a new covalent bond. oxidation - ANSWER -Loss of electrons or an increase in oxidation number. oxidation number - ANSWER -A measure of the number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived from a set of rules. alkali - ANSWER -A type of base that dissolves in water forming hydroxide ions, OH- (aq) ions. alkanes - ANSWER -The homologous series with the general formula: CnH2n+2. alkyl group - ANSWER -An alkane with a hydrogen atom removed, e.g. CH3, C2H5; alkyl groups are often shown as 'R'. amount of substance - ANSWER -The quantity whose unit of the mole. Chemists use 'amount of substance' as a means of counting atoms. anhydrous - ANSWER -A substance that contains no water molecules. anion - ANSWER -A negatively charged ion. atom economy - ANSWER -atom economy = molecular mass of the desired product ×100 sum of molecular masses of all products atomic orbital - ANSWER -A region within an atom that can hold up to two electrons, with opposite spins. atomic (proton) number - ANSWER -The number of protons in the nucleus of an atom acid - ANSWER -A species that is a proton donor. activation energy - ANSWER -The minimum amount of kinetic energy that particles need to have in order to react when they collide addition polymer - ANSWER -A very long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules (monomers).The benefits of buying summaries with Stuvia:
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