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  2. Lone pair - Wikipedia

    en.wikipedia.org/wiki/Lone_pair

    Thus, the number of electrons in lone pairs plus the number of electrons in bonds equals the number of valence electrons around an atom. Lone pair is a concept used in valence shell electron pair repulsion theory (VSEPR theory) which explains the shapes of molecules. They are also referred to in the chemistry of Lewis acids and bases. However ...

  3. Hückel's rule - Wikipedia

    en.wikipedia.org/wiki/Hückel's_rule

    3) are considered examples of a two π electron system, which are stabilized relative to the open system, despite the angle strain imposed by the 60° bond angles. [11] [12] Planar ring molecules with 4n π electrons do not obey Hückel's rule, and theory predicts that they are less stable and have triplet ground states with two unpaired ...

  4. 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).

  5. Electron counting - Wikipedia

    en.wikipedia.org/wiki/Electron_counting

    Neutral counting assumes each bond is equally split between two atoms. This method begins with locating the central atom on the periodic table and determining the number of its valence electrons. One counts valence electrons for main group elements differently from transition metals, which use d electron count.

  6. Ligand bond number - Wikipedia

    en.wikipedia.org/wiki/Ligand_bond_number

    The donation of the lone pair on the nitrogen makes this complex ML 4 X, containing 18 electrons. The traditional coordination number here would be 4, while the CBC more accurately describes the bonding with a LBN of 5. In simple cases, the LBN is often equal to the classical coordination number (ex. Fe(CO) 5, etc.) [5]

  7. C2H4F2 - Wikipedia

    en.wikipedia.org/wiki/C2H4F2

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  8. 1,1-Difluoroethane - Wikipedia

    en.wikipedia.org/wiki/1,1-Difluoroethane

    1,1-Difluoroethane, or DFE, is an organofluorine compound with the chemical formula C 2 H 4 F 2.This colorless gas is used as a refrigerant, where it is often listed as R-152a (refrigerant-152a) or HFC-152a (hydrofluorocarbon-152a).

  9. Sigma-pi and equivalent-orbital models - Wikipedia

    en.wikipedia.org/wiki/Sigma-pi_and_equivalent...

    The σ-π model differentiates bonds and lone pairs of σ symmetry from those of π symmetry, while the equivalent-orbital model hybridizes them. The σ-π treatment takes into account molecular symmetry and is better suited to interpretation of aromatic molecules ( Hückel's rule ), although computational calculations of certain molecules tend ...