Standard 3f Preknowledge
3f) Students know how to draw Lewis dot structures.
CALIFORNIA FRAMEWORKS SUMMARY: A Lewis dot structure shows how valence electrons and covalent bonds are arranged between atoms in a molecule. Teachers should follow the rules for drawing Lewis dot diagrams provided in a chemistry textbook. Students should be able to use the periodic table to determine the number of valence electrons for each element in Groups 1 through 3 and 13 through 18. Carbon, for example, would have four valence electrons. Lewis dot diagrams represent each electron as a dot or an x placed around the symbol for carbon, which is C. A covalent bond is shown as a pair of dots, or x’s, representing a pair of electrons. For example, a Lewis dot diagram for methane, which is CH4, would appear as shown in Figure 3.
Lewis dot diagrams provide a method for predicting correct combining ratios between atoms and for determining aspects of chemical bonds, such as whether they are covalent or consist of single, double, or triple bonds.