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