Rules for making Lewis dot structures
- OCTET RULE: #Bond Pairs + #Lone Pairs = 4
(except for H and atoms of 3rd and higher periods)
2. Place a bond pair (BP) between connected atoms
3. Complete octets by using rest of e- as lone pairs (LP)
4. For atoms with ɠ e-, make multiple bonds to complete octets
5. Assign formal charges : fc = Z - (#BP/2) - (#LP)
Indicate equivalent (RESONANCE) structures
6. Structures with smaller formal charges are preferred
- consider non-octet alternatives (esp. for 3rd, 4th row)
1. Count no. of valence electrons
(- don’t forget to include the charge on molecular ions!)
#lone pairs at central atom in AXn = {(#e-) - 8*n}/2