VSEPR

Homework: -Turn it in

Objectives: -I can reflect upon my assessment performance -I can create a model of a Lewis Dot Structure -I can prepare for the assessment

Where are we at? -Lack of Focus -Lack of Motivation -Lack of Review

Lots of responsibilities…….. -Chunking -Dividing and conquering -Personal accountability

This class is not, -Biology -Standard Chemistry You will be held to a high expectation

Let’s Review -Lewis Dot Structures -Draw Assigned Lewis Dot Structure in the chart -Then draw it on a whiteboard to share with the Class 5 min to draw and solve it, then we will share

Recommendations: -Take accountability for your learning -Nightly review for 10-15 min -Come in with questions -Hold yourself to your set standards

Additionally: Step up and act like upperclassmen Model the behavior you want others to have

Schedule Reset: -Quiz Corrections, to earn up to 60%by Friday -why wrong and what is the right answer -Benchmark: Friday -Assessment: Tuesday, Unit Test, Cumulative M/C and short answer

Reviewing the basics: -Charge -Valence Electrons -Identifying an element -Ionic vs covalent -Ion VS polyatomic ion -Where are transition metals? -Dispersion is not the same as a metallic bond…. -Lewis Dot Steps

-Name the compound Pt₂O₃ SO₂ LiF

Valence Electrons: Model Covalent Compounds -Bonding Pair -Lone Pair

Basics of a Molecule Kit: -Holes -How to make a bond -Color System

Let’s Work through an example: NCl₃ Lewis Dot Build with a molecule kit Draw as you see it when you build it Answer how many bonded atoms and how many lone pairs

Bond Pair VS Lone Pair

Using the molecule kits Make Lewis Dot Build the compound Using the molecule kit with a Partner 3) Check your answers 4) Move on to the prior review portion

Let’s Review: Each group will have one model to present to the class

Reflecting on your model…..

Where are the lone pairs on a molecule kit model? NCl3

Why are these molecules arranged in this pattern?

Lewis Dot Structures for: -CO2 -NH3 -H2O *COH2 -SO2 -CH4

Objectives I can determine the molecular geometry and electron pair geometry of a compound

Yesterday…..

What is VSEPR Theory?

VSEPR: Valence Shell Electron Pair Repulsion -Helps us to predict the geometry (shape of a molecule) -Based on the lone pairs and the bonding pairs Of electrons -Electrons repel each other so an atom is organized and oriented to reduce this

Why is this important? -Structure of molecules determines the chemical properties -Identify the shape of a molecule and the properties to determine how it wil react

What do you need to know about molecular shape? Steric Number # of bonded atoms # of lone pairs Electron Pair Geometry Bond Angle Molecular Geometry Structure Example

What is a lone pair? -Set of two electrons that are not in a chemical bond -Lone pairs have a larger Repulsive force

Steric Number: -Number of units bonded to the central atom -Lone Pairs -Atoms bonded -Example H20, oxygen is the central atom -It has two sets of lone pairs -It has two Oxygen bonded to it Steric Number: 4

What is the steric number of CO2?

Electron Pair Geometry -Molecular shape based on total number of things attached/bonded to central atom (does not distinguish lone pairs from bonded atoms) Molecular Geometry -Molecular shape with or without lone pairs *When no lone pairs, MG and EPG are the same*

EPG and MG for Steric Number =2 *Linear

Bond Angle: -How far apart each pair of electrons is -ie how spread out are the different parts bonded to the central atom

Let’s Work through the Key Examples You Need to Know Steric Number # of bonded atoms # of lone pairs Electron Pair Geometry Bond Angle Molecular Geometry Structure Example 2 3 4

How do we determine the molecular structure? Example: NH3 If only one thing is bonded to the central atom we will not determine any of the characteristics, only if SN is 2 or higher

Independent Practice: -Work Through the Back page -If needed, you may use the molecule kits -Once completed pick up the review sheet

Questions?

Review Problems: -Complete the Review Worksheet for HW