Lewis Dot Covalent - Methods

Method #1:


Method #2:

1. Count the total number of electrons.
2. Draw a structure with single bonds.
3. Starting on the outside start adding dots in pairs so that each element is touching the appropriate number of electrons (H's = 2, all other elements = 8).
   COUNT AS YOU GO - remembering your goal from #1
4. When you only have 4 electrons left - stop and look to see if you're going to run out. If you're going to run out start adding a double or a triple bonds with your final electrons.
5. DOUBLE CHECK -- count to make sure everything is touching the appropriate number. Count to make sure you haven't gone over or below your total number from #1.
6. Double check -- if you have multiple places where a double or triple bond could have gone - double check that you picked the right spot. What's the right spot?? IF elements have a choice they prefer to follow the "Step 5" rule. [ # of valence electrons + bonds = 8]. Sometimes atoms don't get a choice, but when they do they prefer a particular arrangement. Ex: Carbon Dioxide prefers a O=C=O instead of a single and triple bond.