Chemistry revision resources(definitions) 0.0 / 5 ? ChemistryDefinitionsA2/A-levelOCR Created by: Kaur ParamveerCreated on: 18-06-20 21:13 Relative Atomic Mass The weighted mean mass of an atom of an element compared to 1/12 of the mass of an atom of carbon-12 1 of 28 Isotope Atoms with the same number of protons but different number of neutrons 2 of 28 Relative Isotopic Mass The mass of an atom of an isotope of an element compared to 1/12 of the mass of an atom of carbon-12 3 of 28 Relative Molecular Mass The average mass of a molecule compared to 1/12 of the mass of an atom of carbon-12 4 of 28 Relative Formula Mass The average mass of a formula unit compared to 1/12 of the mass of an atom of carbon-12 5 of 28 Mole Amount of any substance containing as many elementary particles as there are carbon atoms in 12g of the carbon-12 isotope 6 of 28 Molecular Formula The actual number of atoms of each type of element in a molecule 7 of 28 Empirical Formula The smallest whole-number ration of atoms of each element in a compound 8 of 28 Strong Acid (HCl) Releases all its hydrogen atoms into solution as H+ ions and completely dissociates in aqueous solution 9 of 28 Weak acid(CH3COOH) only releases a small proportion of its available hydrogen atoms as H+ ions and partially dissociates in aqueous solution 10 of 28 Acids Proton donor. When mixed with water all acids release hydrogen ions(H+) 11 of 28 Bases Proton acceptor. When mixed with water all bases gain hydrogen ions(H+) 12 of 28 Alkali A base that dissolves in water releasing hydroxide ions into the solution 13 of 28 Atom economy A measure of the proportion of reactants atoms that become part of desired product in the balanced chemical equation. 14 of 28 Oxidising Agent Accepts electrons and gets reduced. 15 of 28 Reducing Agent Donates electrons and gets oxidised. 16 of 28 Percentage yield The percentage yield of a chemical reaction shows how much product was actually made compared with the amount of product that was expected. 17 of 28 Disproportionation When an element is both oxidised and reduced in a reaction. 18 of 28 1st ionisation energy Energy required to remove one electron from each atom to form one mole of gaseous 1+ ion 19 of 28 Enthalpy A measure of the heat energy in a chemical system(atoms,molecules or ions) 20 of 28 Standard Enthalpy change of neutralisation The enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O under standard conditions 21 of 28 Standard Enthalpy change of combustion The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions 22 of 28 Standard Enthalpy change of formation The enthalpy change that takes place when one mole of compound is formed from its elements under standard conditions. 23 of 28 Standard Enthalpy change of Reaction The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions. 24 of 28 Activation energy The minimum amount of energy that particles need to have in order to react when they collide. 25 of 28 Heterogeneous catalyst Catalyst that has a different physical state from the reactants 26 of 28 Homogeneous catalyst Catalyst that has a same physical state as the reactants 27 of 28 Periodicity The trends in physical and chemical properties of elements as you go across the periodic table. 28 of 28
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