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Stereochemistry demands special attention because three-dimensionality is the most difficult part of a structure to visualize. Techniques for presenting 3-dimensional structures reflect the tastes of the artist. Three dimensionality is best highlighted by the depictions of bonds, using wedges, bolding, and hashed formats.
An atom (or ion) whose oxidation number increases in a redox reaction is said to be oxidized (and is called a reducing agent). It is accomplished by loss of one or more electrons. The atom whose oxidation number decreases gains (receives) one or more electrons and is said to be reduced. This relation can be remembered by the following mnemonics.
The structural formula of a chemical compound is a graphic representation of the molecular structure (determined by structural chemistry methods), showing how the atoms are connected to one another. [1] The chemical bonding within the molecule is also shown, either explicitly or implicitly.
The nitrogen atom has only 6 electrons assigned to it. One of the lone pairs on an oxygen atom must form a double bond, but either atom will work equally well. Therefore, there is a resonance structure. Tie up loose ends. Two Lewis structures must be drawn: Each structure has one of the two oxygen atoms double-bonded to the nitrogen atom.
An atom bonded to 5 other atoms (and no lone pairs) forms a trigonal bipyramid with two axial and three equatorial positions, but in the seesaw geometry one of the atoms is replaced by a lone pair of electrons, which is always in an equatorial position. This is true because the lone pair occupies more space near the central atom (A) than does a ...
For simple polyatomic molecules with a "central atom" such as methane (CH 4) or carbon dioxide (CO 2), a MO diagram may show one of the identical bonds to the central atom. For other polyatomic molecules, an MO diagram may show one or more bonds of interest in the molecules, leaving others out for simplicity.
A chemical structure of a molecule is a spatial arrangement of its atoms and their chemical bonds. Its determination includes a chemist 's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid.
Structural chemistry is a part of chemistry and deals with spatial structures of molecules (in the gaseous, liquid or solid state) and solids (with extended structures that cannot be subdivided into molecules). For structure elucidation [1] a range of different methods is used.