enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Clar's rule - Wikipedia

    en.wikipedia.org/wiki/Clar's_rule

    The anthracene molecule allows three resonance structures, each with a circle in one ring and two sets of double bonds in the other two. Following rule 4 above, anthracene is better described by a superposition of these three equivalent structures, and an arrow is drawn to indicate the presence of a migrating π-sextet.

  3. Descriptor (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Descriptor_(Chemistry)

    In organic structural chemistry, the configuration of a double bond can be described with cis and trans, in case it has a simple substitution pattern with only two residues. The position of two residues relative to one another at different points in a ring system or a larger molecule can also be described with cis and trans if the structure's ...

  4. Molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Molecular_geometry

    The position of each atom is determined by the nature of the chemical bonds by which it is connected to its neighboring atoms. The molecular geometry can be described by the positions of these atoms in space, evoking bond lengths of two joined atoms, bond angles of three connected atoms, and torsion angles (dihedral angles) of three consecutive ...

  5. Jacobi coordinates - Wikipedia

    en.wikipedia.org/wiki/Jacobi_coordinates

    The position coordinates x j and x k are replaced by their relative position r jk = x j − x k and by the vector to their center of mass R jk = (m j q j + m k q k)/(m j + m k). The node in the binary tree corresponding to the virtual body has m j as its right child and m k as its left child. The order of children indicates the relative ...

  6. Terrace ledge kink model - Wikipedia

    en.wikipedia.org/wiki/Terrace_ledge_kink_model

    In chemistry, the terrace ledge kink (TLK) model, which is also referred to as the terrace step kink (TSK) model, describes the thermodynamics of crystal surface formation and transformation, as well as the energetics of surface defect formation. It is based upon the idea that the energy of an atom’s position on a crystal surface is ...

  7. Ball-and-stick model - Wikipedia

    en.wikipedia.org/wiki/Ball-and-stick_model

    In chemistry, the ball-and-stick model is a molecular model of a chemical substance which displays both the three-dimensional position of the atoms and the bonds between them. [1] The atoms are typically represented by spheres , connected by rods which represent the bonds.

  8. Ring flip - Wikipedia

    en.wikipedia.org/wiki/Ring_flip

    The 1 H NMR spectrum of titanocene pentasulfide features two signals at room temperature, a consequence of its relative rigidity. Bicycloalkane with two "bridgehead carbons" Cyclohexane is a prototype for low-energy degenerate ring flipping. Two 1 H NMR signals should be observed in principle, corresponding to axial and equatorial protons ...

  9. J-coupling - Wikipedia

    en.wikipedia.org/wiki/J-coupling

    Example 1 H NMR spectrum (1-dimensional) of ethanol plotted as signal intensity vs. chemical shift.There are three different types of H atoms in ethanol regarding NMR. The hydrogen (H) on the −OH group is not coupling with the other H atoms and appears as a singlet, but the CH 3 − and the −CH 2 − hydrogens are coupling with each other, resulting in a triplet and quartet respectively.