VSEPR Theory/ Molecular Shapes Lab
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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?