Simple Lewis Dot Structures

1. •• •• • • • •CC• •Si• •O• •B• •N• •• •• • • • • • Si H H H H •• •• •• •• •• •• •• • CC • • • • • B H● ●H ●Cl● O N H● ●H •• •• • ●F● • •• •• •• •• •• •• •• •• •• •• •• • • • • ●Cl● ●Cl● • • • • • • • • • • • • ●F● ●F● ●F● ●F● ●F● ●F● •• •• •• •• •• •• •• •• Simple Lewis Dot Structures 1. Determine the central atom. This is usually the atom that you have the least of in the formula. Ex: H2O BF3 NCl3 C2H6 SiF4 2. Draw the electron dot structure of the central atom. 3. Wherever there are unpaired electrons on the central atom, pair them up with unpaired electrons on the attached atoms. 8 24 26 14 32 H2O: 2+6 = 8 NCl3: 5 + 3(7) = 26 SiF4: 4 + 4(7) = 32 BF3: 3 + 3(7) = 24 C2H6: 2(4) + 6(1) = 14 4. Finally, check your electron count.

2. •• •• O • •• • O •• •• •N• • •• •• •• • N• • • • N• N • • • What to do when you end up with unpaired electrons: Example: Draw the Lewis structure for O2 #VE = 2(6) = 12 • • Pair up the remaining unpaired electrons between the two oxygen atoms. Because each shared pair of electrons represents a chemical bond, there is a double bond between the oxygens in O2. What would the Lewis structure of N2 look like?