AQA A LEVEL CHEMISTRY DEFINITIONS MID-TERM EXAM

AQA A LEVEL CHEMISTRY DEFINITIONS MID-TERM EXAM Aliphatic Hydrocarbon - ANSWER-A hydrocarbon with carbon atoms joined together in straight or branched chains Alkali - ANSWER-A type of base that dissolves in water forming hydroxide ions Alkanes - ANSWER-The homologous series with the general formula CnH2n+2 Alkyl Group - ANSWER-An alkane with a hydrogen ion removed. Alkyl groups are often shown as 'R' Amount of Substance - ANSWER-The quantity whose unit is the mole Anhydrous - ANSWER-A substance containing no water molecules Anion - ANSWER-A negatively charged ion Atom Economy - ANSWER-(molecular mass of the desired product/sum of molecular masses of all products) x100 Atomic Orbital - ANSWER-A region within an atom that can hold up to two electrons, with opposite spins Atomic Number - ANSWER-The number of protons in the nucleus of an atom Average Bond Enthalpy - ANSWER-The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous substance Avogadro Constant - ANSWER-The number of atoms per mole of the carbon-12 isotope. (6.02 x 10^23) Base - ANSWER-A species that is a proton acceptor Relative Atomic Mass - ANSWER-The weighted mean mass of an atom of an element relative to 1/12 of the mass of one atom of carbon-12 First Ionisation energy - ANSWER-The energy required to remove an electron from each atom in one mole of gaseous atoms Acid - ANSWER-A species that is a proton donor Activation Energy - ANSWER-The minimum energy required to start a reaction by the breaking of bonds