MOLECULAR MODEL KITS – THE SHAPES OF MOLECULES Purpose: To use a molecular model kit to determine the shapes of various molecules. Materials: molecular model kit Method: First of all, organize your molecular model kit by making sure you have the parts you will need: 6 chlorine green - 1 hole 18 hydrogen white (or silver)- 1 hole 6 oxygen red - 2 holes 5 carbon 1 nitrogen 1 boron black - 4 holes silver - 3 holes purple - 3 holes 25 white or purple short sticks to represent single bonds 6 white, longer, flexible sticks – use two of these for each double bond Please note that there will be other parts in the kit that you will not be using. They are used by other classes that build different molecules. Keep them in your kit. Next, do the following for each molecule in the observations and conclusions table: 1) Draw the Lewis Structure for the molecule in the space provided in the table. 2) Construct a model of the molecule using the parts from the molecular model kit. Refer to the Lewis Structure to see how those parts should be connected. 3) Draw a diagram of the model in the space provided in the table. Consider the way that the atoms are arranged in the model. Refer to the shapes in the section at the bottom of this page. Then write down the name of the shape or the names of the shapes which the molecule consists of. (Please note that some of the molecules consist of two of the shapes joined together by a shared bond. Also, it is the nature of this kind of kit that the double bonds curve when they are used to join parts together. When you are drawing a diagram of or naming the shape of a molecule with double bonds in it, realize that the double bond goes straight between the atoms that it joins together.) ___________________________________________________________________________ The following list contains the names and representations of some of the common shapes of molecules. A molecule can consist of one of the shapes or a combination of the shapes. There are other shapes but the following ones are sufficient for introductory purposes. trigonal linear pyramidal or bent or angular trigonal planar square planar tetrahedral Observations and Conclusions: Name______________________ A complete set of molecular models was built. ________ (Teacher must initial in this space.) Substance Chemical Formula chlorine gas Cl2 water H20 carbon tetrachloride CCl4 ammonia NH3 boron trihydride BH3 hydrogen peroxide H202 ethanol CH30H carbon dioxide C02 ethene C2H4 Lewis Structure Diagram of Shape and Name(s) of Shape(s)