The Importance of Structural Formulas
A structural formula is a chemical formula that gives you a more complete picture of a compound than its molecular formula could and are more important in chemistry than molecular formula. While a molecular formula, such as H2O, shows the types of atoms in a substance and the number of each kind of atom, a structural formula also gives information about how the atoms are connected together. Some complex types of structural formulas could even give you a picture of how the atoms of the molecule are arranged in space. Structural formulas are most often used to represent important molecular bonds rather than ionic compounds.
There are few different ways to represent compounds in structural formulas, depending on how much detail needs to be shown about the molecule under consideration.
It's necessary to draw structural formulas for organic mixture because in most cases a molecular formula doesn't uniquely represent a single bond. Different compounds having the same molecular formula are called isomers, and the prevalence of organic isomers reflects the extraordinary versatility of carbon in forming strong bonds to itself and to other elements.
The procedure for drawing structural formulas rests on simple covalent bond theory (sharing of electron pairs) and the octet rule. A full discussion of these important topics caould be found in most introductory chemistry texts. It's recommended that a novice first draw Lewis structures, showing the shared and unshared valence shell electrons in a clear and unambiguous fashion. Next, each shared electron pair (covalent bond) could be replaced by a line joining the bonded atoms to give a Kekulé formula. A single bond represents a s-covalent bond. 2 lines (a double bond) represent one s-bond and one p-bond, and 3 lines (a triple bond) indicate one s-bond and two p-bonds.If you want to learn how to read structural formulas click here.
Further simplification of structural formulas might be achieved without any loss of the information they convey. In condensed structural formulas the bonds to each carbon are omitted, but each distinct structural unit (group) is written with subscript numbers designating multiple substituents, including the hydrogens. Shorthand (line) formulas omit the symbols for carbon and hydrogen entirely. Each straight line segment represents a bond, the ends and intersections of the lines are carbon atoms, and the correct number of hydrogens is calculated from the tetravalency of carbon. These notations are illustrated for the 7 C4H10O isomers listed in the following table. Non-bonding valence shell electron pairs are omitted in these formulas:
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