Transcript VSEPR Theory/ Molecular Shapes Lab

 Objective
 Today I will be able to:
 Draw Lewis Structures to represent the valance electrons of atoms
 Represent the formation of ionic and covalent compounds using Lewis
Structures
 Predict the molecular shape of a molecule using the VSEPR theory
 Evaluation/ Assessment
 Informal assessment – Listening to group interactions as they complete
the illustrating ionic and covalent compounds practice and the molecular
shapes lab.
 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: VSEPR Theory
 Explore and elaborate: Molecular Shapes Lab

Informal Assessment
 Evaluate: Exit Ticket
•
Formal assessment
Warm - Up
 How do I determine the number of valence electrons an
atom has?
 What does VSEPR stand for?
 Draw the lewis structure for N2
Warm-Up (Day 2)
 What bond angles does a tetrahedral shaped molecule
have?
 Draw the lewis structure for N2
 What shape and angle does this structure have?
Objective
 Today I will be able to:
 Draw Lewis Structures to represent the valance electrons of
atoms
 Represent the formation of ionic and covalent compounds
using Lewis Structures
 Predict the molecular shape of a molecule using the VSEPR
theory
Homework
 Have a great weekend 
Agenda
 Warm-Up
 VESPER Notes
 Molecular Shapes Lab
 Exit Ticket
Lewis Structures
 Visual representation of the number of valance electrons
in an atom
How to draw Lewis structures
 Write the symbol of the element
 Pretend there are 4 sides
 Use dots to represent the valance electrons around the
symbol
 Place one dot on each side of the element before you form
pairs
 Exception: If there are only 2 valance electrons, they both
go on the same side
Lewis Structures
 C
1s2 2s2 2p2
•
•C •
•
Lewis Structures
 Examples
Mg 1s2 2s2 2p6 3s2
•
Mg •
Lewis Structures
 Cl
1s2 2s2 2p6 3s2 3p5
••
•• Cl ••
•
Lewis Structures
 Cl 1s2 2s2 2p6 3s2 3p5
 Cl-1 1s2 2s2 2p6 3s2 3p6
•
•
[ •• Cl •• ]
••
-1
Valance – Shell Electron Pair
Repulsion Theory (VSEPR)
 In a small molecule, the pairs of valance
electrons are arranged as far apart from
each other as possible
 Explains why atoms form certain shapes
when they bond together
Linear
 Bonds Formed: 2
 Lone Pairs: 0
 Bond Angle: 180o
Trigonal Planar
 Bonds Formed: 3
 Lone Pairs: 0
 Bond Angle: 120o
Tetrahedral
 Bonds Formed: 4
 Lone Pairs: 0
 Bond Angle: 109.5o
Trigonal Pyramidal
 Bonds Formed: 3
 Lone Pairs: 1
 Bond Angle: <109.5o
Bent (Tetrahedral)
 Bonds formed: 2
 Lone Pairs: 2
 Bond Angle: <109.5o
Bent (Trigonal Planar)
 Bonds Formed: 2
 Lone Pairs: 1
 Bond Angle: <120o
Trigonal Bipyramidal
 Bonds Formed:5
 Lone Pairs: 0
 Bond Angle: 120o and 90o
Octahedral
 Description:6
 Lone Pairs: 0
 Bond Angle: 900
Molecular Shapes Lab Directions
 Draw a Lewis Dot Structure for the molecule
 Make a model using the kit and draw the shape on your
paper
 Write the shape name
 Write the bond angle
 Skip POLARITY for now, and we will come back to this
part
 Be careful with the kits, do not drop or lose pieces!
Exit Ticket
 Draw the Lewis Structure for CO2
 Determine the shape and bond angles of CO2 according to
the VSEPR theory.
Exit Ticket – Mol Monday # 7
 How many formula units of LiCl are in 2.30 moles of LiCl?