Download Using Models to Represent Chemical Reactions

Using Models to Represent Chemical Reactions
Look at the reaction above. Make sure that you can identify that the stoichiometric ratio represented in
the balanced chemical equation, can also be represented with molecular models…in this case, space
filling models. See if you can identify how many of the models are molecular compounds, and how
many are molecular elements. How could you tell? How many of the molecules are polar? How many
are nonpolar? Which do you think has the highest boiling point? Why? Also, imagine that 4 molecules
of methane and 8 molecules of oxygen were in a sealed flask. Think about what the flask would look like
after the reaction occurs. Suppose instead you stated with 4 molecules of methane, and 9 molecules of
oxygen. Now what would it look like? This is important as you may see more of these questions on
future AP exams.
Also, I want you to start looking at the three dimensional patterns of the molecules. As we move
steadily through the curriculum, you will be able to identify the first molecules molecular geometry to
be tetrahedral, with bond angles of 109.5o. CO2 has a molecular geometry known as linear, with bond
angles of 180o, and H2O has a molecular geometry known as bent with bond angles of around 104o
degrees. Even though molecular geometry is not touched on until chapter 10 in our textbook, we will be
there before you know it.