Definitions

• Atoms of the same element which therefore have the same number of protons and electrons but a different number of neutrons

• The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12

• The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12

• The electrostatic attraction between positive and negative ions

• A repeating pattern of oppositely charged ions

• The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

• The ability of a bonded atom to attract the bonding electrons in a covalent bond

• A special type of permanent dipole-dipole interaction found between molecules containing: • an electronegative atom (such as F, O and N) with a lone pair of electrons • a hydrogen atom bonded to an electronegative atom

• Repeating trends in the physical and chemical properties of elements across a period

• The energy required for the removal of 1 mol of electrons from 1 mol of gaseous atoms of an element

• The strong electrostatic attraction between cations and delocalised electrons

• Networks of atoms bonded by strong covalent bonds

• A redox reaction in which the same element is both oxidised and reduced simultaneously

• The enthalpy change that takes place when one mole of a compound is formed from its elements under standard conditions

• The enthalpy change that takes place when one mole of a substance is reacted completely with oxygen under standard conditions

• The enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O (l) under standard conditions

• When 1 mole of bonds of gaseous covalent bonds is broken

• A system that minimises pH changes on addition of small amounts of an acid or a base

• The enthalpy change when 1 mole of ionic lattice is formed from its gaseous ions

• The enthalpy change that takes place when 1 mole of a solute dissolves in water

• The enthalpy change that takes place when 1 mole of gaseous ions form hydrated ions

• A measure of the dispersal of energy in a system, that is greater the more disordered a system is

• The e.m.f of a half-cell compared to a hydrogen half-cell

• Elements that form at least one ion with a partially filled d-orbital (not scandium and zinc)