Physical definitions

• Proton: A positively charged subatomic particle present in the nucleus of an atom with a relative mass of 1.
• Heterogeneous system: A system where not all the chemicals are in the same phase.
• Homogeneous system: A system where all the chemicals are in the same phase.
• Le Chatelier’s principle: If a reaction at equilibrium is subjected to a change in concentration, temperature or pressure, the position of equilibrium will move to counteract the change.
• Reversible reaction: Reactions in which the products from the reaction can react together to form the original reactants. The direction of reversible reactions can be changed by changing the conditions.
• Half equation: A full redox equation can be split into two half-equations, one involving oxidation and the other involving reduction.
• Reduction: Process involving the gain of electrons, resulting in a decrease in oxidation number.
• Oxidation state: The charge of an ion or a theoretical charge of an atom in a covalently bonded compound assuming the bond becomes ionic.
• Oxidising agent: Electron acceptors, elements/compounds that accept electrons and become reduced.
• Redox reaction: A reaction in which both reduction and oxidation are occurring simultaneously.
• Reducing agent: Electron donors, elements/compounds that donate electrons and become oxidized.
• Oxidation: Process involving the loss of electrons. Results in an increase in oxidation number.
• Reduction: Process involving the gain of electrons. Results in a decrease in oxidation number.
• Acceleration: Second stage of TOF spectrometry where positively charged ions are accelerated by an electric field to have 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 center of every atom with one or more electrons orbiting it.
• Atomic number: The number of protons in the nucleus.
• Electron: Negatively charged subatomic particle that orbits the nucleus at various energy levels with a relative mass of 1/2000.
• Electron configuration: The distribution of electrons of an atom in orbitals.
• Electrospray ionisation: Method of ionisation in TOF spectrometry where the sample is dissolved and pushed through a fine nozzle at high pressure, gaining an H+ ion through the application of high voltage, and then turned into a gas.
• First ionisation energy: The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
• Ion detection: The fourth stage of TOF spectrometry where the negatively charged plate detects charged particles and produces a mass spectrum.
• Ion drift: The third stage of TOF spectrometry where ions enter a region with no electric field and drift through it, with lighter ions drifting faster.
• Ionisation: The first stage of TOF spectrometry where the sample can be ionised by electrospray ionisation or electron impact ionisation.
• Isotope: Atoms of the same element with the same number
• Mass number: The total number of protons and neutrons in the nucleus.
• Mass spectrometer: A device that provides accurate information about relative isotopic mass and the relative abundance of isotopes.
• Mass spectrometry: A technique used to identify elements and determine relative molecular mass.
• Neutron: A neutral subatomic particle present in the nucleus of an atom with a relative mass of 1.
• Nuclear charge: The total charge of all the protons in the nucleus, which is equivalent to the atomic number and increases across the periodic table.
• Second ionisation energy: The energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
• Sub-shells (orbitals): Divisions within electron shells that further categorize electron distribution in an atom.
• Sub-shells: s, p, d, and f, each with different numbers of orbitals that can hold up to two electrons.
• Time of Flight (TOF) spectrometer: A method of mass spectrometry where an ion's mass-to-charge ratio is determined by a time of flight measurement, consisting of four stages: ionisation, acceleration, ion drift, and detection.
• Atom economy: The measure of the amount of starting materials that end up as useful products.
• Avogadro's constant: The number of atoms, molecules, or ions in one mole of a given substance.
• Concentration: The amount of substance per unit volume, given in g/dm3 or mol/dm3.
• Empirical formula: The smallest whole number ratio of atoms of each element in a compound.
• Limiting reactant: The reactant that is completely used up, limiting the amount of products formed.
• Mole: The mass of a substance containing the same number of units as there are atoms in exactly 12 g of carbon-12.