You can intuitively draw any Lewis Structure on your computer or mobile device. Our example is a question on drawing the structure of formaldehyde or H2CO.
When the question is first opened, a box with a plus symbol is shown below the question. Just click or tap on the plus symbol to open the drawing tool. By default you start with a diatomic molecule with two place-holder elements as solid circles.
Active or selected elements in the structure or bond appear in red. You can change your selection by clicking or tapping on any part of the drawing.
To add more bonds to a specific element, select it and drag your finger or cursor along the right hand dial to change it to however many bonds you'd like. Here we change it to three bonds.
Now we will change the central element to carbon. Since it's already selected, tap or click on the Periodic Table (Change Element) button on the bottom. This will bring up the Periodic Table and will allow you to select any element you'd like. Here we select Carbon and the screen automatically returns to the structure. We repeat this for the two Hydrogens and the Oxygen.
You can use a shortcut to the Periodic Table by just double tapping/clicking the element.
To help you out, there is a convenient tool that allows you to track the number of valence electrons per element. This way you can make sure that each of our Carbon and Oxygen elements are obeying the Octet Rule in this case, since they need eight electrons.
To put a double bond between the Carbon and the Oxygen, tap or click on the bond and use the dial on the left hand side to make it a double bond.
To finish up the structure, we select the Oxygen and use the Electron dial on the left to add two lone pairs of electrons.
To save your work, click done on the top right.
Submit using the "Submit" button on the top right. The app tells you if you've gotten the structure right. If you didn't get the correct structure and multiple attempts and feedback are allowed by your instructor, the app will give you specific feedback on your structure so you can learn from it and correct your understanding.
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