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In particle physics, lepton number (historically also called lepton charge) [1] is a conserved quantum number representing the difference between the number of leptons and the number of antileptons in an elementary particle reaction. [2]
In organic chemistry, neighbouring group participation (NGP, also known as anchimeric assistance) has been defined by the International Union of Pure and Applied Chemistry (IUPAC) as the interaction of a reaction centre with a lone pair of electrons in an atom or the electrons present in a sigma or pi bond contained within the parent molecule but not conjugated with the reaction centre.
The locant is the number of the carbon atom to which the oxygen atom is bonded. If the oxygen is bonded to the middle carbon, the locant is 3. If the oxygen is bonded to an atom on either side (adjacent to an end carbon), the locant is 2 or 4; given the choice here, where the carbons are exactly equivalent, the lower number is always chosen. So ...
For hydrocarbons, the DBE (or IHD) tells us the number of rings and/or extra bonds in a non-saturated structure, which equals the number of hydrogen pairs that are required to make the structure saturated, simply because joining two elements to form a ring or adding one extra bond (e.g., a single bond changed to a double bond) in a structure reduces the need for two H's.
Based on the covalent bond classification method (from where LBN is derived), the equation for determining ligand bond number is as follows: LBN = L + X + Z. Where L represents the number of neutral ligands adding two electrons to the metal center (typically lone electron pairs, pi-bonds and sigma bonds. Most encountered ligands will fall under ...
An atom (or ion) whose oxidation number increases in a redox reaction is said to be oxidized (and is called a reducing agent). It is accomplished by loss of one or more electrons. The atom whose oxidation number decreases gains (receives) one or more electrons and is said to be reduced. This relation can be remembered by the following mnemonics.
) and n s̅ represents the number of strange antiquarks (s). This quantum number was introduced by Murray Gell-Mann. This definition gives the strange quark a strangeness of −1 for the above-mentioned reason. Charm (C): Defined as C = n c − n c̅, where n c represents the number of charm quarks (c) and n c̅ represents the number of charm ...
Once this is determined, all one needs to do is take the total value of Δ f H, subtract the Δ f H caused by the C−(C) 2 (H) 2 group(s), and then divide that number by two (due to two C−(C)(H) 3 groups), obtaining the value of the C−(C)(H) 3 group. From the knowledge of these two groups, Benson moved forward obtain and list functional ...