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  2. Sternal angle - Wikipedia

    en.wikipedia.org/wiki/Sternal_angle

    The sternal angle corresponds to the level of the 2nd costal cartilage on either side, and the level between the fourth and fifth thoracic vertebra. The sternal angle is used to define the transverse thoracic plane which represents the imaginary boundary between the superior and inferior mediastinum. It is also used to identify the second rib ...

  3. Lewis acids and bases - Wikipedia

    en.wikipedia.org/wiki/Lewis_acids_and_bases

    A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may ...

  4. Molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Molecular_geometry

    Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that determine the position of each atom. Molecular geometry influences several properties of a substance ...

  5. Lone pair - Wikipedia

    en.wikipedia.org/wiki/Lone_pair

    Lone pair. In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bond [1] and is sometimes called an unshared pair or non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure.

  6. Ligand - Wikipedia

    en.wikipedia.org/wiki/Ligand

    Ligand. In coordination chemistry, a ligand[a] is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. [1] The nature of metal–ligand bonding can range ...

  7. Skeletal formula - Wikipedia

    en.wikipedia.org/wiki/Skeletal_formula

    The skeletal formula of the antidepressant drug escitalopram, featuring skeletal representations of heteroatoms, a triple bond, phenyl groups and stereochemistry. The skeletal formula, line-angle formula, bond-line formula or shorthand formula of an organic compound is a type of molecular structural formula that serves as a shorthand representation of a molecule's bonding and some details of ...

  8. Trigonal pyramidal molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Trigonal_pyramidal...

    Bond angle (s) 90°<θ<109.5°. μ (Polarity) >0. In chemistry, a trigonal pyramid is a molecular geometry with one atom at the apex and three atoms at the corners of a trigonal base, resembling a tetrahedron (not to be confused with the tetrahedral geometry). When all three atoms at the corners are identical, the molecule belongs to point ...

  9. Tetrahedral molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Tetrahedral_molecular_geometry

    In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos −1 (− 1⁄3) = 109.4712206...° ≈ 109.5° when all four substituents are the same, as in methane (CH4) [1][2] as well as its heavier analogues.