As always n n OWL LonCapa assignments Lecture

As always… n n OWL Lon-Capa assignments Lecture videos Textbook n n Read Do text homework 1

Lewis Structures • • Determine the total number of valence electrons in the molecule. Form at least one bond between atoms in the molecule (a pair of electrons is a bond) Arrange the rest of the electrons (in pairs) to satisfy the octet rule or duet rule (for hydrogen). Watch for exceptions. 2

Clicker Question Which of the following has a Lewis structure most like that of the carbonate ion? a) the nitrate ion b) the sulfate ion c) carbon dioxide d) ozone (O 3) e) nitrogen dioxide 3

Clicker Question Which of the following is the best Lewis structure for the hydrogen thiocyanate molecule (HSCN) taking formal charge into account? Note: the lone pairs are not included in these skeletal structures. Before answering the question, complete the Lewis structures. a) b) c) d) e) H-S-C≡N H-S=C=N H-S≡C-N H-S-C-N At least two of the above structures are equally valid when considering formal charge. 4

Chapter 13 5

VSEPR – General Guidelines • Draw the Lewis structure. • • • If the octet rule is exceeded, add electrons to the central atom. Multiple bonds count as one direction (or one “effective pair”). Consider the lone pairs when determining the geometry. Consider only the atoms when determining the shape. Polarity comes from asymmetry. 6

VSEPR Model 7

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