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  2. IB Group 4 subjects - Wikipedia

    en.wikipedia.org/wiki/IB_Group_4_subjects

    The 3 core sciences namely Biology, Chemistry, and Physics will be updated for first teaching in August 2023, with first examinations in May 2025. The syllabus change was originally scheduled for 2021, though the COVID-19 pandemic caused the IB to delay the syllabus change to 2023. Details of the specific changes can be found on the IBO website.

  3. List of Cambridge International Examinations Ordinary Level ...

    en.wikipedia.org/wiki/List_of_Cambridge...

    Seychelles only, candidates in Seychelles taking O Level English Language had to enter for this syllabus; last exam in 2008 — CIE 1125 English Language (Mauritius) No Yes — Mauritius only, candidates in Mauritius taking O Level English Language must enter for this syllabus or syllabus 1126 — CIE 1126 English Language (Syllabus B ...

  4. List of English homographs - Wikipedia

    en.wikipedia.org/wiki/List_of_English_homographs

    Also, some words only exhibit stress alternation in certain dialects of English. For a list of homographs with different pronunciations (heteronyms) see Heteronym (linguistics) . This list is incomplete ; you can help by adding missing items .

  5. Conjugated system - Wikipedia

    en.wikipedia.org/wiki/Conjugated_system

    Cinnamaldehyde is a naturally-occurring compound that has a conjugated system penta-1,3-diene is a molecule with a conjugated system Diazomethane conjugated pi-system. In theoretical chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases stability.

  6. Negative hyperconjugation - Wikipedia

    en.wikipedia.org/wiki/Negative_hyperconjugation

    In organic chemistry, negative hyperconjugation is the donation of electron density from a filled π- or p-orbital to a neighboring σ *-orbital. [1] This phenomenon, a type of resonance, can stabilize the molecule or transition state. [2] It also causes an elongation of the σ-bond by adding electron density to its antibonding orbital. [1]

  7. Wikipedia : Manual of Style/Chemistry/Compound classes

    en.wikipedia.org/.../Chemistry/Compound_classes

    Articles on compound classes do not feature a chembox. Scope: Ions including the notable conjugate acids and bases, distinct from the parent base and acid. Separate articles are also warranted on certain oxidized or reduced derivatives of elements or neutral molecules. Examples: chloride, oxide, nitrate, triflate. Classes of compounds.

  8. List of conjugated polymers - Wikipedia

    en.wikipedia.org/wiki/List_of_conjugated_polymers

    Class Abbr. Polymer Typical dopants Peak conductivity Peak emission PA: Polyacetylene: PT: Polythiophene: Iodine, bromine, Trifluoroacetic acid, propionic acid, sulfonic acids: 1000 S/cm [3] P3AT: Poly(3-alkylthiophenes) PPy: Polypyrrole: PITN: Poly(isothianaphthene) PEDOT: Poly(3,4-ethylenedioxythiophene) PPV MEH-PPV: alkoxy-substituted poly(p ...

  9. Amine - Wikipedia

    en.wikipedia.org/wiki/Amine

    Amine. In chemistry, amines (/ ə ˈ m iː n, ˈ æ m iː n /, [1] [2] UK also / ˈ eɪ m iː n / [3]) are compounds and functional groups that contain a basic nitrogen atom with a lone pair.Formally, amines are derivatives of ammonia (NH 3 (in which the bond angle between the nitrogen and hydrogen is 107°), wherein one or more hydrogen atoms have been replaced by a substituent such as an ...