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Objectives

Objectives. I CAN determine the geometry and hybridizations of covalent compounds based on the VSEPR Model I CAN predict the polarity of covalent compounds using the VSEPR MOdel. Investigation. Work in groups of 3-4 Complete worksheet and shapes. STOP after every shape 1 minute per shape.

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Objectives

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  1. Objectives • I CAN determine the geometry and hybridizations of covalent compounds based on the VSEPR Model • I CAN predict the polarity of covalent compounds using the VSEPR MOdel

  2. Investigation • Work in groups of 3-4 • Complete worksheet and shapes. STOP after every shape • 1 minute per shape

  3. Key Point 1: What is the VSEPR Model? • The VSEPR (pronounced Vesper) Model is a model that tells us a molecule’s shape • The main rule of the VSEPR model is that electrons will repel each other (negative-negative) so they must be placed as far apart as possible

  4. KP2: How do we use the VSEPR Model? • In a covalent compound, each element has a number of bonding and nonbonding pairs of electronsaround the nucleus. • For example, in H2O, Oxygen has 2 bonding pairs and 2 nonbonding (lone) pairs

  5. Bonding and nonbonding pairs of electrons are also called steric groups • Oxygen has a total of 4 steric groups

  6. KP3: Once you know the number of steric groups, you can figure out the geometry of a compound by looking at the following chart:

  7. Example: List the possible • shapes for the compounds • below: • CO2 • NH3 • PCl3 • BeBr2

  8. KP4: What does the VSEPR Model tell us about polarity? • A molecule will have a DIPOLE when the electrons spend most of their time on one side • Electrons will always spend the most time with the element that is most electronegative (highest electron affinity) • Remember: electron affinity goes UP as we move across the periodic table

  9. Example 1: Let’s look at water. First, draw the bonds in H2O with Lewis Dot Structures.

  10. Example 1: Let’s look at water. First, draw the bonds in H2O with Lewis Dot Structures. Now, figure out what SHAPE H2O will be according to the VSEPR Model: Now, which element is more electronegative? Oxygen or hydrogen? _____________________________ So, the electrons will spend more time with the ___________________ atom, and the pole will look like this:

  11. Example 2: What about CO2? First, draw LDSs: What SHAPE will CO2 be according to the VSEPR Model: Now, which element is more electronegative? Carbon or Oxygen? _____________________________ Will this element have a dipole? ____________________

  12. Example 3--CHALLENGE: What about NO3-? First, draw LDSs What shape will NO3- be according to the VSEPR Model? Now, which element is more electronegative? Nitrogen or Oxygen? _____________________________ Will this element have a dipole? ____________________

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