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Rules for Drawing Lewis Diagrams. Determine how many e- will be in drawing Determine the central atom Least electronegative element Needs most e- for octet Has fewest valence e- First listed in formula (not always!) NEVER H! Connect atoms with covalent bonds (2 e-)
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Rules for Drawing Lewis Diagrams • Determine how many e- will be in drawing • Determine the central atom • Least electronegative element • Needs most e- for octet • Has fewest valence e- • First listed in formula (not always!) • NEVER H! • Connect atoms with covalent bonds (2 e-) • Add electrons to all atoms to get octet • Count and check • Does the number of e- in drawing equal the number of e- calculated?
Rules for Drawing Lewis DiagramsPart II • Follow steps 1-5 from before • IF the answer to question 5 is NO, go to rule 6 (below) 6. More e- in drawing than calculated? • Erase unshared pair • Draw double bond (never on H or halogens) • Erase another unshared pair from other atom in double bond • Count and check