Andrew

Walsh Diagram: This displays how the labels and energies of molecular orbitals of a molecule change with a change in the geometry of that molecule. Wave-Particle Duality: The quantum mechanical result that links the classical ideas of a particle and a wave, saying that each has some of the properties of the other. It is … Read more

VSEPR Theory: See Valence Shell Electron Pair Repulsion Theory. Vacancy: A hole, corresponding to a missing ion, in the ideal structure of a solid. Valence Band: The band in extended molecular orbital theory made up from the valence molecular orbitals on the individual species. It is the highest occupied extended molecular orbital. Valence Shell Electron … Read more

Ultraviolet Photoelectron Spectroscopy (UV-PES): This is a form of spectroscopy which measures the kinetic energy of electrons emitted from a sample when it is irradiated with high energy ultraviolet radiation. Unit Cell: The basic component which, when repeated periodically, makes up the overall structure. Unsaturated: Compare with saturated. A carbon chain is unsaturated if it … Read more

THF: Abbreviation of tetra-hydro-furan (see Furan), a common solvent in organic reactions. TMS: Abbreviation of tri-methyl-silane (-SiMe3). Tautomerism: Some functional groups are related to other functional groups by a simple H shift – they are tautomers, and conversion between them is called tautomerism. The main example of this is keto-enol tautomerism. Template Effect: Complexation of … Read more

SALC: See Symmetry Adapted Linear Combination. SEM: See Scanning Electron Microscopy. Salt Bridge: A glass tube containing an ionic electrolyte which provides electrical connection between two half cells. Saturated: This applies to carbon chains – they are saturated if there are no multiple bonds – i.e. the chain is saturated with hydrogen. Scalar Coupling Constant: … Read more

Racemate: A racemic mixture of two stereoisomers – i.e. a 50/50 mixture so that no optical rotation of light occurs. Racemic: See Racemate. Radial Distribution Function: This is the probability of finding an electron at a given distance from the nucleus, and is different for different atomic orbitals. Radial Node: This is the distance from … Read more

Quantization: Something which is quantized is split into discrete levels, ie: if a something is quantised, it may only have a few discrete values, rather than a continious spectrum of possibilities. Quantum number: A number which labels the quantum state of a system, and thus which may determine various properties of that system. There are … Read more

Para: A position on a phenyl ring – see ortho. Partial Pressure: The pressure that a gas which is a component of a mixture of gases would exert if there were no other gases in the container. Particle in a box: In quantum mechanics, a common model in which a particle is confined to a … Read more

Observable: Some physical property of a system that can be observed. Octet Rule: This states that “each atom in a molecule acquires shares in electrons until its valence shell achieves eight electrons”. Olefin: Old word for alkene. Open System: A system that can exchange both matter and energy with the surroundings. Operator: An instruction to … Read more

NMR timescale: The NMR timescale for an interconversion is the timescale judged relative to the difference between the frequencies of nuclei in the start and finish situations. NMR: See Nuclear Magnetic Resonance. Nearest Neighbour: The atom of closest approach to a given atom in a solid. Neighbouring Group Effect: The effect that local groups of … Read more