Drawing Lewis Structures of Molecules Chapter 4 Section 4

Step 1 Use chemical symbols for the various elements to write the skeletal structure of the compound. –Place least electronegative atom in the center. –Hydrogen, fluorine, and other halogens occupy end positions. –Carbon forms chains.

Step 2 Determine the number of valence electrons associated with each atom and combine them to determine the total number of valence electrons. –Example 1: F 2 2 F atoms x 7 electrons = 14 –Example 2: CH 3 Cl 1 C atom x 4 e - = 4 e - 3 H atoms x 1 e - = 3 e - 1 Cl atom x 7 e - = 7 e - 14 e -

Step 3 Connect the central atom to each of the surrounding atoms using electron pairs. –All atoms want 8 electrons except H which wants 2. –Show all valence electrons including bonding and lone pair electrons. –Check to see that the number of electrons shown matches the number calculated in step 2.

Step 4 If the octet rule is not satisfied for the central atoms, move one or more electron pairs for the surrounding atoms to create double or triple bonds.

Step 5 After you are satisfied with the Lewis structure you have constructed, perform a final electron count verifying the total number of electrons AND the number of electrons around each atom are correct.