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  2. Pi bond - Wikipedia

    en.wikipedia.org/wiki/Pi_bond

    A typical double bond consists of one sigma bond and one pi bond; for example, the C=C double bond in ethylene (H 2 C=CH 2). A typical triple bond, for example in acetylene (HC≡CH), consists of one sigma bond and two pi bonds in two mutually perpendicular planes containing the bond axis. Two pi bonds are the maximum that can exist between a ...

  3. Pi-stacking - Wikipedia

    en.wikipedia.org/wiki/Pi-stacking

    Pi stacking is repulsive as it places carbon atoms with partial negative charges from one ring on top of other partial negatively charged carbon atoms from the second ring and hydrogen atoms with partial positive charges on top of other hydrogen atoms that likewise carry partial positive charges. [2] In staggered stacking, one of the two ...

  4. Single bond - Wikipedia

    en.wikipedia.org/wiki/Single_bond

    The structure of pi bonds does not allow for rotation (at least not at 298 K), so the double bond and the triple bond which contain pi bonds are held due to this property. The sigma bond is not so restrictive, and the single bond is able to rotate using the sigma bond as the axis of rotation (Moore, Stanitski, and Jurs 396-397). Another ...

  5. Rotamer - Wikipedia

    en.wikipedia.org/wiki/Rotamer

    In chemistry, rotamers are chemical species that differ from one another primarily due to rotations about one or more single bonds. Various arrangements of atoms in a molecule that differ by rotation about single bonds can also be referred to as different conformations. Conformers/rotamers differ little in their energies, so they are almost ...

  6. Rotational partition function - Wikipedia

    en.wikipedia.org/wiki/Rotational_partition_function

    Rotational energies are quantized. For a diatomic molecule like CO or HCl, or a linear polyatomic molecule like OCS in its ground vibrational state, the allowed rotational energies in the rigid rotor approximation are = = (+) = (+). J is the quantum number for total rotational angular momentum and takes all integer values starting at zero, i.e., =,,, …, = is the rotational constant, and is ...

  7. Orbital overlap - Wikipedia

    en.wikipedia.org/wiki/Orbital_overlap

    In chemical bonds, an orbital overlap is the concentration of orbitals on adjacent atoms in the same regions of space. Orbital overlap can lead to bond formation. Linus Pauling explained the importance of orbital overlap in the molecular bond angles observed through experimentation; it is the basis for orbital hybridization.

  8. Orbital hybridisation - Wikipedia

    en.wikipedia.org/wiki/Orbital_hybridisation

    In ethene, the two carbon atoms form a σ bond by overlapping one sp 2 orbital from each carbon atom. The π bond between the carbon atoms perpendicular to the molecular plane is formed by 2p–2p overlap. Each carbon atom forms covalent C–H bonds with two hydrogens by s–sp 2 overlap, all with 120° bond angles. The hydrogen–carbon bonds ...

  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).