internuclear axis

Examples of internuclear axis in the following topics:

• Explanation of Valence Bond Theory

  • $\sigma$ bonds occur when orbitals overlap between the nuclei of two atoms, also known as the internuclear axis.
  • Atomic orbitals from two atoms overlap in the region between the nuclei (internuclear axis).

• Bonding and Antibonding Molecular Orbitals

  • A bond involving molecular orbitals that are symmetric with respect to rotation around the bond axis is called a sigma bond (σ-bond).
  • In this anti-bonding MO, with energy much higher than the original AOs, any electrons present are located in lobes pointing away from the central internuclear axis.
  • For a π-bond, corresponding bonding and antibonding orbitals would not have such symmetry around the bond axis, and are designated π and π* respectively.

• The Phase of Orbitals

  • A bond involving molecular orbitals that are symmetric with respect to rotation around the bond axis is called a sigma bond (σ-bond).
  • In this anti-bonding molecular orbital with energy much higher than the original atomic orbitals, any electrons present are located in lobes pointing away from the central internuclear axis.
  • For a π-bond, corresponding bonding and antibonding orbitals would not have such symmetry around the bond axis and would be designated π and π*, respectively.

• Double and Triple Covalent Bonds

  • Similar to double bonds, no rotation around the triple bond axis is possible.
  • The electron density corresponding to the shared electrons is not concentrated along the internuclear axis (i.e., between the two atoms), unlike in sigma bonds.

• Bond Energy

  • A Morse curve shows how the energy of a two atom system changes as a function of internuclear distance.
  • At internuclear distances in the order of an atomic diameter, attractive forces dominate.
  • The internuclear distance at which the energy minimum occurs defines the equilibrium bond length.

• Bond Lengths

  • X-ray diffraction of molecular crystals allows for the determination of the three-dimensional structure of molecules and the precise measurement of internuclear distances.

• Chirality and Symmetry

  • The boat conformation of cyclohexane shows an axis of symmetry (labeled C2 here) and two intersecting planes of symmetry (labeled σ).
  • The notation for a symmetry axis is Cn, where n is an integer chosen so that rotation about the axis by 360/nº returns the object to a position indistinguishable from where it started.
  • In addition to the point of symmetry noted earlier, (E)-1,2-dichloroethene also has a plane of symmetry (the plane defined by the six atoms), and a C2 axis, passing through the center perpendicular to the plane.

• Major Features of a Phase Diagram

  • These diagrams plot pressure on the y-axis and temperature on the x-axis.

• Strong Acid-Weak Base Titrations

  • The curve depicts the change in pH (on the y-axis) vs. the volume of HCl added in mL (on the x-axis).

• Homonuclear Diatomic Molecules