Saturday, June 18, 2011

Activity 3: Common Molecules, Structures and Names

Activity 3: Common Molecules, Structures and Names

Now that we have some familiarity of atoms, Activity 3 explores how elements come together to make molecules.

In brief, the electrons that surround elements interact in a good way with electrons around other elements to create chemical bonds. These chemical bonds are what hold atoms together to form molecules. Molecules are the most common form of chemical substances that we experience everyday in our lives. If you go to Tylenol on wikipedia there is a good example of information on the molecule and the chemical structure of Tylenol. In the upper right of the page there is a structure called a Ball and Stick model. This model represents atoms that are held together by chemical bonds. In this model (which is quite common for chemistry) the black balls represent carbon atoms, the white balls represent hydrogen atoms, the blue balls represent nitrogen atoms, and the red balls represent oxygen atoms. Notice that it is possible to have 1 or even 2 bonds between some of the atoms. The other image is called a Kekule Diagram. This is the short-hand method that scientists use to draw molecules. It is very common for scientists to not indicate the carbon and hydrogen atoms since these are so common in molecules it becomes quite tedious! So it becomes necessary to understand that the Kekule structures are short-hand notation for the more accurate Ball and Stick model. The other common information needed for molecules is the molecular formula (this is the count of each type of atom in the molecule) and the formal chemical name. While in wikipedia on Tylenol, if you click on acetominophen or paracetamol you come to a page that has the detailed chemical information on this common drug. On the upper right is the same images. Under the images you will notice the systematic or IUPAC name. This is the name that scientists call this molecule. Also on the right you will notice the detailed chemical properties for this molecule, one of which is the formula, C8H9NO2. So, in Tylenol there are 8 carbon atoms, 9 hydrogen atoms, 1 nitrogen atom and 2 oxygen atoms.

For this activity students are to explore the web and find chemical structures and names for everyday molecules. Remember Wikipedia tends to be a great resource for this info!


1. Post a picture of three 3-dimensional Ball and Stick molecular models(choose your three favorite molecules) that you have created with common items around your home (e.g., toothpicks and marshmallows). Also post a molecular structure image(image from the web, of either a Kekule Structure or a Ball and Stick Model) and the IUPAC name of the molecule.

2. Post an image from the web, the chemical systematic (IUPAC) name, common name, and the molecule formula for 20 chemicals that you use or eat. Explore the ingredients of things like cosmetics and foods.

3. Look over your molecules and the bonding characteristics, how many bonds does each of the following elements typically have? Carbon? Hydrogen? Oxygen? Back in your homemade structures, this would be the number of toothpicks attached to each element.

4. What does IUPAC stand for?

5. As you explore ingredients, notice how everything around us is made up of chemicals consisting of atoms bound together into molecules. But what about companies that claim their products are chemical free! How can this be? Here is an example:

Do a little web searching and propose what chemicals are actually in this product.

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