Research Articles
Cooper, M., Grove, N., Underwood, S., & Klymkowsky, M. (2010) Lost in Lewis Structures: an investigation of student difficulties in developing representational competence. Journal of Chemical Education 87(8): 869-874.
Cooper M., Underwood S., Hilley C., & Klymkowsky M. (2012) Development and Assessment of a Molecular Structure and Properties Learning Progression. Journal of Chemical Education 89(11):1351-1357.
Drawing Lewis Structures
Lewis structures are often taught as a set of rules for students to learn without any real meaning. In many ways it's like a Sudoku puzzle with the goal of getting all the numbers (in this case valence electrons and octets) to add up. Some students really like the puzzle aspect. But what's usually missing is an understanding of what Lewis structures can tell us about molecules.
Knowledge of Lewis structures can help us predict:
- the shape of a molecule.
- the reactivity of a molecule and how it might interact with other molecules.
- the physical properties of a molecule such as boiling point, surface tension, etc.
Recent work by Cooper (2010, 2012) suggests that teaching the why aspect first supports student learning. Based on constructivist learning theories students need to understand and practice using information about the structure of molecules from Lewis Structures to predict molecular shape, reactivity, and physical properties.
List of Lewis Structures
Acetone | BF3 | BH4- | BrF5 | BrO3- | C2H2 | C2H4 | ClO- |
CH4 | ClO2- | ClO2 | ClO4- | CO | CS2 | H2O | H3O+ |
HCl | HNO3 | I3- | ICl4- | IF5 | N2 | N3- | NH2OH |
NH3 | NO2- | NO2 | NO3- | O2 | OF2 | PCl5 | PH3 |
PO33- | PO43- | SCl2 | SF4 | SF6 | SO3 | SO42- | XeF2 |
XeF4 | OH- | BrF3 | O3 | H2O2 |
Promoting the WHY of Lewis Structures
Many students, and teachers, search the web for information on drawing Lewis structures for specific compounds. For example, over 1,500 people search on the term "NH3 Lewis structure" each month on Google. Most often they find a procedural description of the steps necessary to draw a Lewis structure for NH3.
Since most web searches will direct learners and teachers to pages with specific molecules, web pages for the most commonly search molecules are provided via the links above. On each page information on why we do Lewis structures will be presented along with a link to a YouTube video detailing the more mechanical process of writing the structure. By providing the embedded video it is expected that visitors will stay on the page longer and learn about why Lewis structures are important.