| Isotope | atoms of the same element with the same number of protons and electrons but different numbers of neutrons. Isotopes of an element have different masses |
| Relative Isotopic mass | the mass of an atom of an isotope compared with 1/12th mass of an atom of carbon-12. |
| Relative atomic mass | he weighted mean mass of an atom compared with 1/12th mass of an atom of carbon-12. |
| Acid | Proton donor |
| Base | proton acceptor |
| Alkaline | Proton acceptor which Releases hydroxide ions in solution |
| 1st ionisation energy | The energy required to remove one electron from one mole of gaseous atoms to form one mole of 1+ gaseous ions. E.g M(g) à M+(g) +e- |
| 2nd ionisation energy | The energy required to remove one electron from one mole of gaseous atoms to form one mole of 1+ gaseous ions. E.g M(g) à M+(g) +e- |
| Ionic bonding | the strong electrostatic force of attraction between (positively and negatively) oppositely charged ions |
| Covalent bond | The electrostatic attraction between a shared pair of electrons and the nuclei on bonding atoms. |
| Metallic bonding | The electrostatic attraction between a shared pair of electrons and the nuclei on bonding atoms. |
| Electronegativity | The ability of an atom to attract a pair of electrons in a covalent bond. |
| Disproportionation | is a redox reaction in which the same element is both oxidised and reduced simultaneously. |
| Enthalpy change of combustion | Enthalpy change when reacting one mole of a substance completely with oxygen under standard conditions with everything in standard state. |
| Enthalpy change of formation | Enthalpy change when forming one mole of a substance from its constituent elements. |
| Enthalpy change of neutralisation | Reaction of acid and base to form one mole of water. |
| Bond enthalpy | Breaking of 1 mol of bonds in gaseous molecules |
| Catalyst | Speeds up a reaction lowers activation energy provides and alternative pathway |
| Activation energy | the minimum amount of energy needed to start a reaction |
| Homologous series | series of organic compounds having the same functional group but with each successive member differing by CH2) |
| Homolytic bond fission | each bonding atom receiving one electron from the bonded pair, forming two radicals when a covalent bond is broken |
| Heterolytic fission | one bonding atom receiving both electrons from the bonded pair when a covalent bond is broken |
| Radical | A species with an unpaired electron |
| Curly arrow | movement of a pair of electrons |
| Structural isomer | Molecule with same molecular formula but different structural formula. |
| Stereoisomer | Same structural formula but different arrangement of atoms in a space |
| Sigma bond | overlaps of orbitals directly between the bonding atoms |
| Pi bond | sideways overlap of adjacent p-orbitals above and below the plane of bonding atoms |
| Electrophile | Electron pair acceptor |
| Nucleophile | electron pair donor |
| Mole fraction | mole fraction = moles of component /total moles |
| Partial pressure | pp= mole fraction x total pressure |
| Difference between Monobasic acid and Dibasic | m=acid which donates 1 proton
d= donates 2 protons |
| PH | ph= -log[H+} |
| pka | pka= -log[ka] |
| Buffer | Substance which minimises and resists the change in pH formed from a weak acid and conjugate bas |
| Lattice enthalpy | enthalpy change when forming 1 mole of ionic lattice from its gaseous ions |
| Enthalpy of hydration | enthalpy change when 1 mole of gaseous ion dissolves in water to form aq ions |
| Enthalpy of solution | enthalpy change when 1 mole of an ionic compound dissolves in water molecules |
| Entropy | disorder in system |
| oxidising agent | species which is reduced when oxidising another species |
| Reducing agent | species which is oxidised when reducing another species |
| Standard electrode | Ability to be oxidised or reduced compared to hydrogen electrode |
| Transition elements | forms at least one ion with a partially filled d orbitals |
| Monodentate ligand | Donates one pair of electrons to Forms 1 co-ordinate bond with a central metal ion |
| Bidentate ligand | Donates two pair of electrons to Forms 2 co-ordinate bond with a central metal ion |
| Complex ion | Ion formed from a central metal ion and multiple co-ordinate bonds from ligands |
