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  2. E–Z notation - Wikipedia

    en.wikipedia.org/wiki/E–Z_notation

    E–Z configuration, or the E–Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry.It is an extension of cis–trans isomer notation (which only describes relative stereochemistry) that can be used to describe double bonds having two, three or four substituents.

  3. List of character tables for chemically important 3D point groups

    en.wikipedia.org/wiki/List_of_character_tables...

    The finite group notation used is: Z n: cyclic group of order n, D n: dihedral group isomorphic to the symmetry group of an n–sided regular polygon, S n: symmetric group on n letters, and A n: alternating group on n letters. The character tables then follow for all groups.

  4. Time unit box system - Wikipedia

    en.wikipedia.org/wiki/Time_unit_box_system

    The term "TUBS" and the notation was originally used by musicologists Philip Harland and James Koetting to notate polyrhythms in African music in the early 1960s. [1] However, Joseon composer Bak Yeon(박연)'s invention of similar but unrelated notation jeongganbo (정간보, image ) to notate Korean court music dates back to middle of the ...

  5. Absolute configuration - Wikipedia

    en.wikipedia.org/wiki/Absolute_configuration

    In chemistry, absolute configuration refers to the spatial arrangement of atoms within a molecular entity (or group) that is chiral, and its resultant stereochemical description. [1] Absolute configuration is typically relevant in organic molecules where carbon is bonded to four different substituents .

  6. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.

  7. Descriptor (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Descriptor_(Chemistry)

    See: E-Z notation Violet leaf aldehyde, systematic name (E,Z)-nona-2,6-dienal, is a compound having one (E)- and one (Z)-configured double bond. The descriptors (E) (from German entgegen, 'opposite') and (Z) (from German zusammen, 'together') are used to provide a distinct description of the substitution pattern for alkenes, cumulenes or other double bond systems such as oximes.

  8. Glyceraldehyde - Wikipedia

    en.wikipedia.org/wiki/Glyceraldehyde

    Glyceraldehyde has one chiral center and therefore exists as two different enantiomers with opposite optical rotation: . In the D/L nomenclature, either D from Latin Dexter meaning "right", or L from Latin Laevo meaning "left"

  9. Woodward–Hoffmann rules - Wikipedia

    en.wikipedia.org/wiki/Woodward–Hoffmann_rules

    Thermolysis converts 1 to (E,E) geometric isomer 2, but 3 to (E,Z) isomer 4.. The Woodward–Hoffmann rules (or the pericyclic selection rules) [1] are a set of rules devised by Robert Burns Woodward and Roald Hoffmann to rationalize or predict certain aspects of the stereochemistry and activation energy of pericyclic reactions, an important class of reactions in organic chemistry.