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  2. Bond order - Wikipedia

    en.wikipedia.org/wiki/Bond_order

    The bond order itself is the number of electron pairs (covalent bonds) between two atoms. [3] For example, in diatomic nitrogen N≡N, the bond order between the two nitrogen atoms is 3 (triple bond). In acetylene H–C≡C–H, the bond order between the two carbon atoms is also 3, and the C–H bond order is 1 (single bond).

  3. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    The order of sequence of atomic orbitals (according to Madelung rule or Klechkowski rule) can be remembered by the following. [2] Order in which orbitals are arranged by increasing energy according to the Madelung rule. Each diagonal red arrow corresponds to a different value of n + l.

  4. Three-center four-electron bond - Wikipedia

    en.wikipedia.org/.../Three-center_four-electron_bond

    This bonding scheme is succinctly summarized by the following two resonance structures: I—I···I − ↔ I − ···I—I (where "—" represents a single bond and "···" represents a "dummy bond" with formal bond order 0 whose purpose is only to indicate connectivity), which when averaged reproduces the I—I bond order of 0.5 obtained ...

  5. Valence bond theory - Wikipedia

    en.wikipedia.org/wiki/Valence_bond_theory

    For example, a bond between two s-orbital electrons is a sigma bond, because two spheres are always coaxial. In terms of bond order, single bonds have one sigma bond, double bonds consist of one sigma bond and one pi bond, and triple bonds contain one sigma bond and two pi bonds. However, the atomic orbitals for bonding may be hybrids.

  6. IB Group 4 subjects - Wikipedia

    en.wikipedia.org/wiki/IB_Group_4_subjects

    The Chemistry, Biology, Physics and Design Technology was last updated for first teaching in September 2014, with syllabus updates (including a decrease in the number of options), a new internal assessment component similar to that of the Group 5 (mathematics) explorations, and "a new concept-based approach" dubbed "the nature of science". A ...

  7. IB Group 5 subjects - Wikipedia

    en.wikipedia.org/wiki/IB_Group_5_subjects

    The Group 5: Mathematics subjects of the IB Diploma Programme consist of two different mathematics courses, both of which can be taken at Standard Level (SL) or Higher Level (HL). [1] To earn an IB Diploma, a candidate must take either Mathematics Applications and Interpretation (SL/HL) or Mathematics Analysis and Approaches (SL/HL), as well as ...

  8. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    Initially, one line (representing a single bond) is drawn between each pair of connected atoms. Each bond consists of a pair of electrons, so if t is the total number of electrons to be placed and n is the number of single bonds just drawn, t−2n electrons remain to be placed. These are temporarily drawn as dots, one per electron, to a maximum ...

  9. List of chemical elements - Wikipedia

    en.wikipedia.org/wiki/List_of_chemical_elements

    118 chemical elements have been identified and named officially by IUPAC.A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z).