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NetGRADE Instructions
A program for learning chemical nomenclature and stereochemistry by doing.
The program initiates by displaying a dot at the center of the screen. This dot
represents carbon with an implicit number of hydrogens (CHn), initially methane
(CH4).
GRADE works better on a PC than a MAC (or UNIX?) and with Explorer than
Netscape. When using GRADE or any applet with a JIT (Just in Time) compiler, you
will notice hesitation the first time you exercise a function. This is the time
it takes to translate the Java multi-platform byte code to your machine's native
instructions. The program then runs faster as the compiler saves the translated
machine code. Also be patient and don't keep on pressing buttons without a
response! Consider that this is all happening over the Web!
General Buttons:
- List of elements: Contains the elements that can be added to the
structures you draw.
- Add: This is the first label on the second button. Clicking on this
button will scroll you through the following:
- Add the selected atom by dragging away from the center dot or
clicking on a pre-existing atom, respectively. New atoms are added at the
same level in or out of the plane of the screen as the atom to which they
are being connected. Drag between any two atoms to get a double (green)
or triple (blue) bond. Use the explicit carbon
label (C) to suppress the evaluation of the configuration of a carbon. Also,
use the (C) symbol, along with the appropriate number of hydrogens, to draw
aromatic compounds. Do not include alternating double and single bonds as
would really be drawing cyclohexa-1,3,5-triene and not benzene.
- Delete: Delete an atom or bond by clicking on the atom or center
of the bond, respectively. Take care to not split the molecular model into
more than one piece and then press "Arrange". You get a bunch of little
dots.
- Rotate: Rotate as a function of 2 or 3D controls.
There are two visual cues that will help you understand what is in front and
in back of the center of rotation. The atoms that are in front follow the
cursor and appear in large bold. The atom label in back is smaller and moves
opposite of the cursor.
- Move: Your picture will move and stay, left or right, up or down
following the cursor, but the center of rotation is still in the center of
the screen.
- Resize: Drag up or down to change the size of your model. This
option can also be used to get the mirror image of the model by over
reducing its size.
- 2D: This button changes rotation from 2 to 3 dimensional and back.
- Arrange: Rearranges, centers and resizes your model. Rotate your
initial drawing out of plane to help expand the model into the third
dimension. Notice how double and triple bonds are separated.
- Clear: This clears both the text area and the drawing area. In a
quiz, only your answer is cleared.
Tutorial (NAME) Button:
- Name: Press to get the name of your model (independent of its
conformation) or the relation of your model to a structure in the GRADE
database. Typing in a name in the text field and pressing "enter" or "return"
will get you a structure. Look at
byname for the
list of available compounds.
Quiz Buttons:
- Enter: Once you are finished typing or drawing your answer, press
Enter to check it. You will get the message "Correct", "Incorrect" or
the stereochemical relation of your answer to the approved one. You get three
chances to answer correctly but points are taken off. We are only trying to
help you see what you really know so don't cheat. You can take the quiz as
many times as you want for the highest score or just to learn more.
- Cont: Press to get your next question or to see your final score.
NetGRADE reverts to the tutorial when you finish your quiz. Press "reload" or
"refresh" on your browser to try again but make sure you exit the browser when
you finish so that no one else submits a quiz with your name.
Stereo/Mono Button:
- Toggle between a stereo and mono view of your structures. In the stereo
view you will see two different images on the screen. One is blue and the
other is red. Use red-blue filter glasses to see these images combine into a
three dimensions image.
What's with the status bar?
- When you draw a structure the status bar at the bottom of the browser
gives you a running count of the molecular formula, the formula weight and the
number of rings and unsaturations you have to break to make an acyclic
saturated compound.
- When you press the Name button the status bar shows the indices used to
recognize your chemical structure. These indices are the Hosoya's Z (useful
for correlating boiling points to structures), the Ulam (a connectivity
index), the Atom (a combined atom content-connectivity index) and the Stereo
Index (a complex number indexing achiral compounds as real numbers, chiral
compounds with an imaginary component). How can we tell enantiomers apart?
Last you see a chiral or achiral label. Please note this is by configuration
not conformation.
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