Chemistry 220 uses Jmol Applets. Firefox from Mozilla is the recommended browser. Make sure that you have the latest version of Java. Make sure that Java is turned on in your browser. Go to the security tab in Java. [For a Mac: System Preferences> Java>Security>Exceptions.] Locate Exceptions. Enter: classes.yale.edu. Click OK. You should be able to see the structure of cyclohexane on the homepage and at the bottom of this page. You may have to restart your browser or reboot your computer. Links to non-classes.yale.edu sites that employ Java applets, such as Jmol, will not work unless an exception is made.