1) antimony tribromide _______SbBr3___ 2) hexaboron silicide ____________B6S____________ 3) chlorine dioxide ____________ClO2__________ 4) iodic acid ________________HIO3______________ 5) iodine pentafluoride ________IF5_______________ 6) dinitrogen trioxide ____________N2O3______________ 7) ammonia ________________NH3_________ 8) hypophosphorous acid ______________H3PO2_____________ ANSWERS

9) P4S5 ___tertaphosphorous pentasilicide____ 10) O2 ___oxygen__________ 11) HNO4 _____pernitric acid______ 12) Si2Br6 _____disilicon hexabromide____________ 13) SCl4 _____silicon tertachloride__________ 14) CH4 _____carbon tetrahydride___(methane)______ 15) H2SO3 ______sulfurous acid__________ 16) NF3 ________nitrogen trifluoride_____________ ANSWERS

9.3 Molecular Structure

Molecular Structures Ball and Stick model Stick Model Space Filling

Structural Formula H2SO4 NH3 Water CH4 O H N H H O S O H H H H O H H C H H O H Structural Formula

H2SO4 NH3 O H O S O H H N H H Water CH4 H H C H H O H Lewis Structure

General Lewis Structure Rules C4H8O2 Predict Atom locations H is always terminal Lowest Electronegativity is central atom H O 3.44 C 2.55 General Lewis Structure Rules

General Lewis Structure Rules C4H8O2 Predict Atom locations H is always terminal Lowest Electronegativity is central atom Find total number of bonding e- H – C – O – 1 x 8 = 8 36 4 x 4 = 16 6 x 2 = 12 General Lewis Structure Rules

General Lewis Structure Rules Predict Atom locations H is always terminal Lowest Electronegativity is central atom Find total number of bonding e- Find number of pairs C4H8O2 36 /2=18 General Lewis Structure Rules

General Lewis Structure Rules C4H8O2 18 Predict Atom locations H is always terminal Lowest Electronegativity is central atom Find total number of bonding e- Find number of pairs Place one bond between central atom and each outer atom -13 C H O 5 General Lewis Structure Rules

General Lewis Structure Rules C4H8O2 18 Predict Atom locations H is always terminal Lowest Electronegativity is central atom Find total number of bonding e- Find number of pairs Place one bond between central atom and each outer atom Place remaining e- pairs around outer atoms -13 H 5 H C H C O H H O C H C H H General Lewis Structure Rules

General Lewis Structure Rules C4H8O2 Predict Atom locations H is always terminal Lowest Electronegativity is central atom Find total number of bonding e- Find number of pairs Place one bond between central atom and each outer atom Place remaining e- pairs around outer atoms Form double (triple) bonds to give central atom an octet H H C H C O H H O C H C H H General Lewis Structure Rules

Polyatomic Ions 8 H – 1x4=4 N – 5x1=5 9 S – 6x1 = 6 O – 6x4 = 24 30 Cations NH4+ Anions Sulfate 8 26 H – 1x4=4 N – 5x1=5 9 S – 6x1 = 6 O – 6x4 = 24 30 (+) = -1 8 (2-) = 2 32 Polyatomic Ions

Cations NH4+ Anions Sulfate 8 26 2- + S O N H Polyatomic Ions

Get to Work Draw Structural Formulas H C2H6 N2 CO2 O3 N N O C O Get to Work Draw Structural Formulas

O3 O O Resonance

N O Resonance Structures - A molecule has resonance when you can draw multiple Lewis Structures NO3- - N O Resonance Structures

N O Resonance Structures - A molecule has resonance when you can draw multiple Lewis Structures NO3- - N O Resonance Structures

O3 SO2 O S O Second Chance

Exceptions Odd number of e- NO2 O N O Fewer than 8 e- Expanded Octet BH3 H B H H SF6 S F Exceptions

Exceptions Fewer than 8 e- Coordinate Covalent Bond 1 atom donates both e- to share H B H N H Exceptions