Drawing Lewis Structures (electron dot diagrams) 4.1

Drawing Lewis Structures Step #1 Decide which atoms are bonded The central atom is usually more metallic, or less electronegative not usually oxygen, never hydrogen

Drawing Lewis Structures Step #2 Count the valence electrons you have, add or subtract electrons according to charge of polyatomic ions.

Drawing Lewis Structures Step #3 Place 2 electrons in each bond between atoms (remember that they all will have at least a single bond)

Drawing Lewis Structures Step #4 Complete the octets of the atoms attached to the central atom, by adding lone pairs. Place any remaining electrons on the central atom, in pairs

Drawing Lewis Structures Step #5 If the central atom does not have an octet, form double or triple bonds

Drawing Lewis Structures Step #6 Draw the Lewis structure and enclose polyatomic ions within square brackets showing ion charge

Drawing Lewis Structures Examples: HClO3 and SO3

Non-Octet Compounds Some compounds will contain central atoms that do not follow the octet rule. The four possibilities for non-octet compounds are: Where more than 4 atoms are bonded to the central atom such as PCl5. A noble gas is participating in bonding such as XeF4. Where the central atom has less than 8 valence electrons such as BH3. Where molecules contain an odd number of nonbonding electrons such as NO.