Molecule drawing questions (Lewis structures)

Select  Expand or collapse keyboard control (top toolbar) to show or hide keyboard instructions below the canvas.

To begin, select  Launch Tips Tour to step through quick on-screen tips that identify options for drawing or editing molecules.

When available, open the Introduction to Mastering assignment and select the Introduction to Molecule Drawing Answers item. This assignment provides practice items for different kinds of questions. You can usually return to this assignment anytime during the course, even after its due date. If you completed this assignment, you can usually rework its items for practice.

• From the top toolbar, select  Undo,  Erase (or  Select and Erase), or even  Reset, as needed.
• If you select Erase — When you finish erasing, either select a new control or deselect Erase.
• You can edit a submitted drawing answer as long as you have another chance to answer the question.

See alternate instructions for chemical drawing using the Marvin chemical editor.

1. Place some common elements on the canvas.
   1. With Carbon selected in the toolbar, point to place it on the canvas. (Active buttons have a dark background.)
   2. Select Oxygen and place it on the canvas twice.
   3. Select Hydrogen and position it.
2. Place an element from the periodic table on the canvas.
   1. Select Periodic Table to choose Sodium.
   2. Close the periodic table to place the sodium atom on the canvas.
3. Add bonds between atoms.
   1. Select Double Bond from the toolbar, point on the top Oxygen atom on the canvas and drag to make the bond with the Carbon atom.
   2. Switch to Single Bond from the toolbar, point to Carbon on the canvas and add one bond to the Hydrogen atom and another bond to the lower Oxygen atom.
4. Add electron pairs to an atom.
   1. Select Paired Electrons from the toolbar.
   2. Select the top Oxygen atom on the canvas (it changes color) twice to add 2 electron pairs.
      
   3. Select the bottom Oxygen atom on the canvas 3 times to add 3 electron pairs.
5. Increase or decrease the charge for an atom.
   1. Select Increase Charge from the toolbar and select Sodium on the canvas.
   2. Select Decrease Charge from the toolbar and select the bottom Oxygen on the canvas.
6. Select Submit to submit your answer.
   Important: If you move on to another item or close Mastering before selecting Submit, your molecular drawing work is not saved.

The default charge of atoms is 0.

Increase the charge of a atom or bracket

1. Select  Increase Charge.
2. On the canvas, select the atom or bracket for which you want to increase the charge.
3. Continue to select, until you see the charge value you want. The maximum charge is 8+.

Decrease the charge on an atom or bracket

1. Select  Decrease Charge.
2. On the canvas, select the atom or bracket for which you want to decrease the charge.
3. Continue to select, until you see the charge value you want. The minimum charge is 8-.

Choose  Select from the toolbar and then either select a molecule part (atom, bond, charge, or electron) on the canvas or select a group of items by dragging. Selected items change from black to green on the canvas.

• To turn off Select mode so you can continue drawing: Choose Select again.
• To deselect molecule parts: Either choose Select again or place your pointer in a blank area of the canvas while Select is still active.

• Select Undo to undo your last action.

  To delete only parts of your drawing — Select Erase.

  To start over completely — Select Reset.

• Select Redo to redo your last action.

Zoom In: Select to enlarge your view of the drawing.

Zoom Out: Select to reduce your view of the drawing.

Zoom Fit: Use to enlarge your drawing to fit the canvas with some white space around it. If the drawing becomes too large: Select Undo. (Using Zoom Out only reduces the image in very small increments.)

Select Copy Answer Strings to copy the correct expression, answer string, and parameters to your clipboard.

When you copy the correct answer, you can compare the answer string to your own drawing if you believe your answer was incorrectly marked wrong.

To open the periodic table —
Select Periodic Table. Close the periodic table to return to the drawing canvas.

To change your view of the periodic table —
Choose one of the following color schemas to refer to when drawing molecules. Your selection remains active if you close the periodic table and then return to it within the same Mastering session.

• CPK: Active automatically. Choosing CPK makes the element names appear in CPK colors. These colors are commonly used to distinguish atoms of different chemical elements in molecular ball and stick models.
• Standard state: Select to see the standard state of elements in the periodic table, whether gas, solid, liquid, or other.
• Blocks: Select to distinguish which block an element belongs to. Use the color legend to identify s Block (includes Group 1 alkali metals with one valence electron & Group 2 alkali earth metals with two valence electrons), d Block (transition metals with electrons in d orbitals), p Block (elements with valence electrons in the p orbital), and f Block (inner transition metals with electrons in f orbitals).
• Metals/Nonmetals: Select for elements to appear classified as metallic or nonmetallic. Use the color legend to identify elements labeled as alkali metal, alkaline earth metal, other metal, metalloid, transition metal, or nonmetal.