Molecular Polarity

   Objective  Today I will be able to:  Predict the molecular shape of a molecule using the VSEPR theory • Predict the polarity of molecules based on the molecular shape Evaluation/ Assessment  Informal assessment – Listening to group interactions as they completethe molecular shapes lab and practice worksheets.

 Formal Assessment – Analyzing student responses to the exit ticket and the practice worksheets. Common Core Connection  Make sense of problem and persevere in solving them  Reason abstractly and quantitatively  Use appropriate tools strategically  Look for and make use of structure

Lesson Sequence

• • • • • • Warm – Up Explain: Molecular Polarity Elaborate: Molecular Shapes Lab Polarity – Formal and informal assessment Elaborate: Molecular Polarity Worksheet Elaborate: VSEPR Theory Practice Evaluate: Exit Ticket • Formal assessment

Warm - Up

• • • What does VSEPR stand for?

What is the VSEPR Theory?

Why do the molecules form these specific shapes?

Objective

• Today I will be able to: – Predict the molecular shape of a molecule using the VSEPR theory – Predict the polarity of molecules based on the molecular shape

Homework

• Finish VSEPR Theory Practice

Agenda

• • • • • • Warm-Up Molecular Polarity Notes Predicting Polarity in Molecular Shapes Lab Molecular Polarity Worksheet VSEPR Theory Practice Exit Ticket

Polarity

Molecular Polarity

• • • Just because a molecule has polar bonds does not mean it is a polar molecule We have to look at the overall shape of the molecule Two or more polar bonds may cancel each other out leading to a nonpolar molecule

A molecule will be nonpolar if…

• • • • All of the terminal atoms (or groups) are the

same

If all of the terminal atoms (or groups) are symmetrically arranged around the central atom The terminal atoms (or groups) have the same charges Example: CO 2

A molecule will be polar if…

• • • • One or more terminal atoms differ from each other The terminal atoms are not symmetrically arranged Polar molecules will have one slightly positive end and one slightly negative end Example – – H 2 O NH 3

Polarity Examples

Molecular Shapes Lab

• • • Revisit the molecular shapes lab Fill out the column labeled polarity Please ask questions!

Molecular Polarity Worksheet

Complete in class and we will review selected answers as a group

VSEPR Theory Practice

Complete worksheet, whatever is not finished will be your homework

Exit Ticket

• • • • • Determine if the following molecules are polar or nonpolar • (Hint: Draw a Lewis structure) Cl 2 H 2 O CH 3 Br CH 4