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  2. Tetrahedron - Wikipedia

    en.wikipedia.org/wiki/Tetrahedron

    The central angle between any two vertices of a perfect tetrahedron is arccos(− ⁠ 1 / 3 ⁠), or approximately 109.47°. [39] Water, H 2 O, also has a tetrahedral structure, with two hydrogen atoms and two lone pairs of electrons around the central oxygen atoms. Its tetrahedral symmetry is not perfect, however, because the lone pairs repel ...

  3. Crystal system - Wikipedia

    en.wikipedia.org/wiki/Crystal_system

    The diamond crystal structure belongs to the face-centered cubic lattice, with a repeated two-atom pattern.. In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point).

  4. Tetragonal crystal system - Wikipedia

    en.wikipedia.org/wiki/Tetragonal_crystal_system

    An example of the tetragonal crystals, wulfenite Two different views (top down and from the side) of the unit cell of tP30-CrFe (σ-phase Frank–Kasper structure) that show its different side lengths, making this structure a member of the tetragonal crystal system. In crystallography, the tetragonal crystal system is one of the 7 crystal systems.

  5. Crystal structure - Wikipedia

    en.wikipedia.org/wiki/Crystal_structure

    In monoclinic, trigonal, tetragonal, and hexagonal systems there is one unique axis (sometimes called the principal axis) which has higher rotational symmetry than the other two axes. The basal plane is the plane perpendicular to the principal axis in these crystal systems.

  6. Board foot - Wikipedia

    en.wikipedia.org/wiki/Board_foot

    The board foot or board-foot is a unit of measurement for the volume of lumber in the United States and Canada. It equals the volume of a board that is one foot (30.5 cm) in length, one foot (30.5 cm) in width, and one inch (2.54 cm) in thickness, or exactly 2.359 737 216 liters. Board foot can be abbreviated as FBM (for "foot, board measure ...

  7. Tetradentate ligand - Wikipedia

    en.wikipedia.org/wiki/Tetradentate_ligand

    If all the feet of the tripod are symmetrical and identical to each other, there will be only one way to attach in an octahedral coordination. However, there are two non-equivalent positions left on the central atom, so if two different monodentate ligands or an unsymmetrical bidentate ligand attaches, there will be two possible isomers.

  8. Ligand field theory - Wikipedia

    en.wikipedia.org/wiki/Ligand_field_theory

    Griffith and Orgel used the electrostatic principles established in crystal field theory to describe transition metal ions in solution and used molecular orbital theory to explain the differences in metal-ligand interactions, thereby explaining such observations as crystal field stabilization and visible spectra of transition metal complexes.

  9. Crystal field theory - Wikipedia

    en.wikipedia.org/wiki/Crystal_field_theory

    In a tetrahedral crystal field splitting, the d-orbitals again split into two groups, with an energy difference of Δ tet. The lower energy orbitals will be d z 2 and d x 2 - y 2 , and the higher energy orbitals will be d xy , d xz and d yz - opposite to the octahedral case.