AQA CHEMISTRY A LEVEL WITH COMPLETE SOLUTIONS

AQA CHEMISTRY A LEVEL WITH COMPLETE SOLUTIONS covalent bond - ANSWER-a shared pair of electrons between non-metal elements co-ordinate bond - ANSWER-a shared pair of electrons where both electrons are supplied by one atom repulsion in shapes of molecules - ANSWER-Lone pair-lone pair > lone pair-bonding pair > bonding pair-bonding pair electronegativity - ANSWER-the power of an atom to attract the pair of electrons in a covalent bond hess' law - ANSWER-Total enthalpy change for a reaction is independent of the route chosen mean bond enthalpy - ANSWER-The energy required to break a covalent bond into gaseous atoms averaged over different molecules Bonds broken - bonds made Relative atomic mass - ANSWER-The average mass of an atom of an element, relative to 1/12th of the mass of an atom of Carbon-12 Relative molecular mass - ANSWER-Average mass of a molecule compared to 1/12th of the mass of a carbon-12 atom The Avogradro constant - ANSWER-the number of particles in a mole ideal gas equation - ANSWER-pV = nRT empirical formula - ANSWER-the simplest whole number ratio of atoms of each element in a compound percentage atom economy - ANSWER-(Mass of desired product/total mass of reactants) x 100 ionic bonding - ANSWER-the electrostatic attraction between oppositely charged ions in a lattice activation energy - ANSWER-The minimum amount of energy needed to start a chemical reaction catalyst - ANSWER-A substance that increases the rate of a chemical reaction without being changed by providing an alternative reaction pathway by lowering activation energy Le Chatelier's principle - ANSWER-When a system in dynamic equilibrium is subjected to change, the position of equilibrium will shift to oppose the change. oxidising agents - ANSWER-electron acceptors reducing agents - ANSWER-electron donors Enthalpy of formation - ANSWER-Enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions in their standard states