Module 2

• Atomic number


  Number of protons in the atom (proton number)
• Isotope


  Atoms of the same element with different numbers of neutrons and different masses but the same proton number
• Mass number


  Sum of the number of protons and neutrons in the nucleus (nucleon number)
• Ion


  A positively or negatively charged atom where the number of electrons is different to the number of protons
• Cation


  A positively charged ion with fewer electrons than protons
• Anion


  A negatively charged ion with more electrons than protons
• Relative isotopic mass


  The mass of an isotope compared with one twelfth of the mass of an atom of carbon-12
• Relative atomic mass


  The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12
• Mass spectrometer


  An instrument used to determine the relative masses of atoms by the deflection of their ions on a magnetic field
• Binary compound


  A compound containing two elements only
• Polyatomic ion


  An ion containing more than one atom of more than one element
• Diatomic molecule


  A molecule consisting of two atoms
• Formula unit


  The lowest whole-number ratio of ions in an ionic compound
• Amount of substance


  The quantity whose unit of the mole. Chemists use amount of substance as a means of counting atoms
• Avogadro's constant


  6.02 x 10^23 mol -1, the number of atoms per mole of carbon-12
• Molar mass


  The mass per mole of a substance, in units of g mol-1
• Molecular formula


  A formula that shows the number and type of atoms of each element present in a molecule
• Empirical formula


  A formula that shows that the simplest whole-number ratio atoms of each element present in a compound
• Relative molecular mass


  The weighted mean mass of a molecule of a compound compared with one-twelfth of the mass of an atom of carbon-12
• Relative formula mass


  The weighted mean mass of the formula unit of a compound compared with one-twelfth of the mass of an atom of carbon-12
• Analysis


  A detailed examination of the elements or structure of something...................................................
• Hydrated


  A crystalline compound containing water molecules
• Water of crystallisation


  Water molecules that are bonded into a crystalline structure of a compound
• Anhydrous


  Containing no water molecules
• Volume


  The amount of space that a substance or object occupies, or that is enclosed within a container
• Concentration


  A measurement of how much solute exists within a certain volume of solvent
• Standard solution


  A solution of a known concentration
• Molar gas volume


  The volume per mole of gas molecules at a stated temperature and pressure
• Stoichiometry


  The ratio of the amount, in moles, of each substance in a chemical reaction
• Theoretical yield


  The yield resulting from complete conversion of reactants into products
• Percentage yield


  (actual yield of a product/theoretical yield of product) x100
• Actual yield


  The amount of product obtained from a reaction
• Limiting reagent


  The reagent that is not in excess,which will be used up first and stop the reaction
• Atom economy


  (Sum of molar masses of desired products)/(sum of molar masses of all products) x 100%
• Strong acid


  An acid that dissociates completely in solution
• Dissociation


  The separation of a substance into two or more simpler substances, or of a molecule into atoms or ions, by the action of heat or a chemical process
• Weak acid


  An acid that dissociates only partially in solution
• Base


  A compound that neutralises an acid to form a salt
• Neutralises


  The reaction between an acid and a base to produce a salt
• Salt


  The product of a reaction in which the H+ ions from the acid are replaced by metal or ammonium ions