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ATOMIC THEORY
Lesson 5 - Page 1

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CHEMICAL FORMULAS

Chemical formulas help to understand how elements “hook up” to make up a compound.   It is basically an easy short cut by identifying the elements and the number of atoms that are needed to make the molecule stable. 

Jons Jacob Berzelius (1779-1848), a Swedish chemist invented the chemical short cut used today.  He was a professor of chemistry and pharmacy and this system of notations helped him to show the chemical composition easily to his medical students.   The only difference is he used a superscript (H²O) instead of today’s subscript (H₂O).  The subscript represents a molecule that has more than one atom of that element.  For example, a molecule of glucose (sugar) has a chemical formula of C₆H₁₂O₆ or six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.

In this exercise we will look closer at compounds that have varying amounts of only hydrogen and carbon called hydrocarbons.  The group is an excellent example of how materials can be made by changing the portion of each element.  The number of electrons in the outer shells of both elements produces a large number of compounds that can be formed. For example,   petroleum products are derived from hydrocarbons.