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Enantiotopic groups are identical and indistinguishable except in chiral environments. For instance, the CH 2 hydrogens in ethanol (CH 3 CH 2 OH) are normally enantiotopic, but can be made different (diastereotopic) if combined with a chiral center, for instance by conversion to an ester of a chiral carboxylic acid such as lactic acid, or if coordinated to a chiral metal center, or if ...
For two indistinguishable particles, a state before the particle exchange must be physically equivalent to the state after the exchange, so these two states differ at most by a complex phase factor. This fact suggests that a state for two indistinguishable (and non-interacting) particles is given by following two possibilities: [2] [3] [4]
Protons, composed of two up and one down quark (uud) Neutrons, composed of two down and one up quark (ddu) Hyperons, such as the Λ, Σ, Ξ, and Ω particles, which contain one or more strange quarks, are short-lived and heavier than nucleons. Although not normally present in atomic nuclei, they can appear in short-lived hypernuclei.
Protons and neutrons, each with a mass of approximately one atomic mass unit, are jointly referred to as nucleons (particles present in atomic nuclei). One or more protons are present in the nucleus of every atom. They provide the attractive electrostatic central force which binds the atomic electrons.
Magnetic inequivalence may occur with H 2 C-CH 2 fragments that are subdivided into two groups of two in either geminal relationships via a mirror plane along the C-C bond, i.e. H A H A′ C-CH B H B′, or in vicinal relationships via a mirror plane bisecting the C-C bond, i.e. in H A H B C-CH A′ H B′, [4] or via a rotational axis of ...
The subatomic particles considered important in the understanding of chemistry are the electron, the proton, and the neutron. Nuclear physics deals with how protons and neutrons arrange themselves in nuclei. The study of subatomic particles, atoms and molecules, and their structure and interactions, requires quantum mechanics.
The particles in the final state are represented by lines pointing in the direction of the final state (e.g., to the right). QED involves two types of particles: matter particles such as electrons or positrons (called fermions) and exchange particles (called gauge bosons). They are represented in Feynman diagrams as follows:
However, the prefixes can usefully describe the relative configuration of a compound that has the following properties: it has at least four C atoms, exactly two of those C atoms are stereocenters, the stereocenters are adjacent, and the two substituents on each stereocenter can clearly be labeled as "larger" (usually a heteroatom such as N, O ...