OCR AS Chemistry 0.0 / 5 ? ChemistryAll TopicsASOCR Created by: GemmaO29Created on: 19-10-17 16:08 Activation Energy The minimum energy required to start a chemical reaction 1 of 38 Acid A species that releases H+ ions in aqueous solution 2 of 38 Empirical Formula The simplest whole number ratio of atoms of each element present in a compound 3 of 38 Avogadro's Constant Number of Atoms in 1 mole of a compound 6.02x1023 mol-1 of Carbon 12 4 of 38 Molar Mass The mass per mole of a substance in units gmol-1 5 of 38 Amount of Substance/Mole The qwuantity whose unit is the mole. Chemists use amount of substance as a mean of counting atoms 6 of 38 First Ionisation Energy The enery required to remove one electron form one mole (each atom) of gaseous atoms of an element to form 1 mole of gaseous 1+ ions 7 of 38 Water of Crystallisation Water molecules that are bonded in a compound 8 of 38 Hydrated A compound containing water molecules 9 of 38 Anhydrous Contains no water molecules 10 of 38 Salt The product of a raction in which H+ ions are replaced by metal or ammonium ions in the acid 11 of 38 Neutralisation The reaction between and acid and a base to form a salt and water H+ + OH- makes H2O 12 of 38 Alkali A type of base that dissolves in water and releases OH- ions 13 of 38 Base A compound that neutralises an acid to form a salt 14 of 38 Molecular Formula A formula that shows the number and type of atoms of each element present in a molecule 15 of 38 Disproportionation A redox reaction in which the same element is both oxidised and reduced 16 of 38 Acid A species that release H+ ions in an aqueous solution 17 of 38 Relative atomic mass The weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of Carbon 12 18 of 38 Relative isotopic mass The mass of an atom of an isotope compared to 1/12th of the mass of an atom of Carbon 12 19 of 38 Isotope Atoms of the same element with different numbers of neutrons and different masses 20 of 38 Mass Number The sum of the number of protons and the number of neutrons in the nucleus Oxygen- 16 Nitrogen-14 21 of 38 Metallic bonding The electorstatic attraction between positive metals ions and delocalised electron 22 of 38 Hydrogen Bonding A stron dipole-dipole attraction between hydrogen atom NH,OH, or HF or a lone pair of electorns in H, N , O ,F 23 of 38 Permenant dipole-dipole interactions Attractive forces between the permenant dipoles in different molecules 24 of 38 Induced Dipole-dipole interactions (London Forces) Attractive forces between induced dipoles in different molecules 25 of 38 Dipole A seperation in electrical charge so that one atom of a polar covalent bond has a slight positive charge and the other negative 26 of 38 Non-polar With no charge seperation across a bond or in a molecule 27 of 38 Polar A molecule with a permenant dipole one ned is negative and the other is positive 28 of 38 Electronegativity A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond 29 of 38 Redox Reaction A reaction in which the reactants are both oxidised and reduced 30 of 38 Dative (Coordinate) covalent bond A shared pair of electrons in which the bonded pair of electrons has been provided by one atom only 31 of 38 Covalent bond The electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms 32 of 38 Ionic bond The electrostatic attraction between positively and negatively charged ions 33 of 38 Periodicity A repeating trend in properties of the elements across each period of the periodic table 34 of 38 Reduction Gain of electrons or a decrease in oxidation number 35 of 38 Oxidation Loss of electrons or increase in oxidation number 36 of 38 Atomic number The number of protons in the nucleus of an atom 37 of 38 Thermal Decomposition The break down of a compound under heat 38 of 38
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