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  2. Pi bond - Wikipedia

    en.wikipedia.org/wiki/Pi_bond

    Quadruple bonds are extremely rare and can be formed only between transition metal atoms, and consist of one sigma bond, two pi bonds and one delta bond. A pi bond is weaker than a sigma bond, but the combination of pi and sigma bond is stronger than either bond by itself. The enhanced strength of a multiple bond versus a single (sigma bond) is ...

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

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

    Linus Pauling proposed that the double bond in ethylene results from two equivalent tetrahedral orbitals from each atom, [5] which later came to be called banana bonds or tau bonds. [6] Erich Hückel proposed a representation of the double bond as a combination of a sigma bond plus a pi bond.

  4. Electronic properties of graphene - Wikipedia

    en.wikipedia.org/wiki/Electronic_properties_of...

    Sigma and pi bonds in graphene. Sigma bonds result from an overlap of sp 2 hybrid orbitals, whereas pi bonds emerge from tunneling between the protruding p z orbitals. For clarity, only one p z orbital is shown with its three nearest neighbors.

  5. Valence bond theory - Wikipedia

    en.wikipedia.org/wiki/Valence_bond_theory

    Pi bonds occur when two orbitals overlap when they are parallel. [9] 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.

  6. Ligand field theory - Wikipedia

    en.wikipedia.org/wiki/Ligand_field_theory

    The greater stabilization that results from metal-to-ligand bonding is caused by the donation of negative charge away from the metal ion, towards the ligands. This allows the metal to accept the σ bonds more easily. The combination of ligand-to-metal σ-bonding and metal-to-ligand π-bonding is a synergic effect, as each enhances the other.

  7. Greek letters used in mathematics, science, and engineering

    en.wikipedia.org/wiki/Greek_letters_used_in...

    Archimedes' constant (more commonly just called Pi), the ratio of a circle's circumference to its diameter; the prime-counting function; the state distribution of a Markov chain; in reinforcement learning, a policy function defining how a software agent behaves for each possible state of its environment; a type of covalent bond in chemistry

  8. Sigma bond - Wikipedia

    en.wikipedia.org/wiki/Sigma_bond

    Organic molecules are often cyclic compounds containing one or more rings, such as benzene, and are often made up of many sigma bonds along with pi bonds. According to the sigma bond rule, the number of sigma bonds in a molecule is equivalent to the number of atoms plus the number of rings minus one. N σ = N atoms + N rings − 1

  9. Bond order - Wikipedia

    en.wikipedia.org/wiki/Bond_order

    In molecules which have resonance or nonclassical bonding, bond order may not be an integer.In benzene, the delocalized molecular orbitals contain 6 pi electrons over six carbons, essentially yielding half a pi bond together with the sigma bond for each pair of carbon atoms, giving a calculated bond order of 1.5 (one and a half bond).