Structural Formula
The structural formula of a chemical compound is a graphical representation of the molecular structure (You can read here about molecular formulas) and they show the arrangement of the atoms within the molecules. The chemical bonding within the molecule is too shown as either explicitly or implicitly. There are 3 common representations used in publications, condensed, all Lewis type and line-angle formula. There are also few formats used for structural formula representation in chemical databases, such as InChI and CML.
Unlike all molecular formulas or chemical names, structural formulas manifacture a very powerful picture of the molecular structure. Chemists nearly usually describe a chemical reaction or synthesis using structural formula rather than chemical names, because the structural formula gives the chance to chemist to visualize the changes that occur.
The complete molecular formula C2H6O doesn't really tell you which atoms are bonded to which other atoms. Even knowing how many valence electrons each atom has and needs, you would still be able to properly combine the atoms together in more than one way. Each way would be a different compound. The electron dot diagram for one of those arrangements is shown above. It shows how each atom has shared electrons to fill up its valence shell (or energy level) with eight electrons (2 for hydrogen). The electron also shows which atom is bonded to which other atoms and what kinds of bonds are used. The structural formula does everything same, but with fewer strokes and less clutter. In these completed formulas each line represents a single covalent chemical bond. A double bond is represented by a double line and a triple bond by a triple line. In ethene (ethylene), C2H4, the carbon atoms are joined by a double bond. The structural formula of ethene is:(In lots of representations of structural formulas, the angles of the lines indicating bonds do not necessarily have meaning.) In ethyne (acetylene), C2H2, the carbon atoms are joined by a triple bond.
The electron dot diagram and structural formula for another compound that has the same molecular formula, C2H6O. In each case notice how the structural formula gives you lots of information about how the molecule is put together than does the molecular formula. Throughout the next several lessons you should use structural formulas instead of molecular formulas, because structural formulas are easy to learn. If you want to learn how to read structural formulas click here
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