physical

• ionisation energy: the enthalpy required to remove 1 mole of the outermost electrons from 1 mole of gaseous atoms or ions
• successive ionisation energies get greater each time, because there are the same number of protons but less electrons therefore become harder to remove
• factors that affect ionisation energy: nuclear charge, distance from nucleus, shielding, spin-spin repulsion
• Acceleration: Second stage of TOF spectrometry involves accelerating the positively charged ions to the same kinetic energy.
• Atom: The smallest part of an element that can exist, all substances are made up of atoms.
• Atomic nucleus: Positively charged object composed of protons and neutrons at the centre of every atom with one or more electrons orbiting it.
• Atomic number: The number of protons in the nucleus.
• Electron: Negatively charged subatomic particle which orbit the nucleus at various energy levels, relative mass of 1/2000.
• Electron configuration: The distribution of electrons of an atom in orbitals, for example, Ca: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2.
• Electron impact ionisation: Method of ionisation in TOF spectrometry involves vaporising the sample and firing high energy electrons at it, causing an electron to be knocked off each particle to produce 1+ ions.
• Electrospray ionisation: Method of ionisation in TOF spectrometry involves dissolving the sample and pushing it through a fine nozzle at a high pressure, causing each particle to gain an H + ion.
• First ionisation energy: The energy required to remove 1 mole of electrons from 1 moles of gaseous atoms to form 1 mole of gaseous 1+ ions, for example, O(g)→ O + (g) +e -.
• Ion detection: Fourth stage of TOF spectrometry involves the negatively charged plate detecting charged particles and producing a mass spectrum.
• Hess’s law states that the enthalpy change of a reaction is independent of the route taken.
• In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds.
• Simple molecular crystal structures are structures in which the atoms are joined by strong covalent bonds.
• Mean bond enthalpy is the enthalpy change when one mole of a specified covalent bond is broken averaged out across the range of compounds.
• An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases.
• Standard conditions are 100 kPa and a stated temperature (generally 298K).
• Standard enthalpy of combustion (∆ c H Ɵ) is the enthalpy change when one mole of a substance is burned in excess oxygen under standard conditions.
• Valence shell electron pair repulsion theory is used to deduce the geometry of molecules.
• Lone pair–lone pair repulsion is greater than lone pair–bond pair repulsion, which is greater than bond pair–bond pair repulsion.
• Standard enthalpy of formation (∆ f H Ɵ) is the enthalpy change when one mole of a substance in its standard state under standard conditions is formed from its elements under standard conditions.
• In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.
• An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.
• Molar enthalpy change is the enthalpy change per mole of substance.
• Weak intermolecular forces mean simple molecules have low melting and boiling points.
• Enthalpy change (∆H) is the heat energy change measured under conditions of constant pressure.
• Van der Waals forces, also known as induced dipole–dipole, exist between all molecules and arise due to fluctuations of electron density within a nonpolar molecule.
• Calorimetry is the process of measuring the amount of energy absorbed or released during a chemical reaction.
• Ion drift: Third stage of TOF spectrometry involves the ions entering a region with no electric field, so they drift through it, the lighter the ion, the faster they will drift.
• Ionisation: First stage of TOF spectrometry involves the sample being ionised by electrospray ionisation or electron impact ionisation.
• Isotope: Atoms of the same element with the same number of protons but a different number of neutrons
• Mass number: The total number of protons and neutrons in the nucleus.
• Mass spectrometer: A mass spectrometer gives accurate information about relative isotopic mass and also about the relative abundance of isotopes.
• Mass spectrometry: Mass spectrometry can be used to identify elements and determine relative molecular mass.
• Half equation is a full redox equation that can be split into two half-equations, one involving oxidation and the other involving reduction.
• If pressure is increased, the position of equilibrium shifts towards the side with the fewest number of molecules.
• The area under the curve of Maxwell-Boltzmann distribution indicates the total number of particles present.
• Reducing agent is an element or compound which donates electrons causing itself to be oxidised.