Chemistry Grade 11
Term 2 - 2020-2021
Chemistry Grade11
Term 3: 2020-2021
Week 2
Day 2
Section 5: Mollecular geometry
HOLT McDOUGAL
Modern Chemistry
Chapter 6: chemical bonding
Section 5: Mollecular geometry
GRADE 11– CHEMISTRYWEEK 3 - DAY 2 AY 2020 – 2021
Chapter 6: chemical bonding
Section 5:
Molecular Geometry
ALWAYS KEEP THESE IN MIND.
NEVER FORGET THE CLASS RULES AND
REGULATIONS!
Section 5: Mollecular geometry
Section 5: Mollecular geometry
AMBITION
.
Grade 10: Chapter 15: section# 2 : PH meter #492,493
HS-PS1-3
Plan and conduct an investigation individually and collaboratively to produce data
to serve as the basis for evidence, and in the design: decide on types, how much,
and accuracy of data needed to produce reliable measurements and consider
limitations on the precision of the data and refine the design accordingly.
Topic: Molecular Geometry
Students will be able to explain VESPR Theory, Predict the shapes of molecules
or polyatomic ions using VSEPR theory.
Section 5: Mollecular geometry
Chapter 6
Chemical Bonding
Section 5: Mollecular geometry
Elaborate (SC: I can Predict the shapes of molecules or polyatomic ions using
VSEPR theory.)
Evaluate:(SC: I can answer application questions in Learning Check.)
Section 5: Mollecular geometry
Section 5: Mollecular geometry
Section 5: Mollecular geometry
Poly atomic ions
•
According to the VSEPR theory, the NH4+
molecule ion possesses tetrahedral molecular
geometry. Because the center atom, nitrogen,
has four N-H bonds with the hydrogen atoms
surrounding it. The H-N-H bond angle is 109.5
degrees in the tetrahedral molecular geometry.
Nitrate ion
The nitrate has 3 electron domains and no lone pairs.
Therefore, NO3– molecular geometry is slightly bent and is
trigonal planar. The bond angle is 120o.
Geometry: Trigonal Planar
Bond Angle: 120o
Section 5: Mollecular geometry
Section 5: Mollecular geometry
VSEPR Theory
• VSEPR theory can also account for the geometries of
molecules with unshared electron pairs.
• examples: ammonia, NH3, and water, H2O.
• The Lewis structure of ammonia shows that the
central nitrogen atom has an unshared electron pair:
HNH
H
• VSEPR theory postulates that the lone pair occupies
space around the nitrogen atom just as the bonding
pairs do.
VSEPR Theory
• Taking into account its unshared electron pair, NH3
takes a tetrahedral shape, as in an AB4 molecule.
• The shape of a molecule refers to the positions of
atoms only.
• The geometry of an ammonia molecule is that of a
pyramid with a triangular base.
• H2O has two unshared pairs, and its molecular
geometry takes the shape of a “bent,” or angular,
molecule.
VSEPR Theory
• Unshared electron pairs repel other electron pairs
more strongly than bonding pairs do.
• This is why the bond angles in ammonia and water are
somewhat less than the 109.5° bond angles of a
perfectly tetrahedral molecule.
VSEPR Theory
• The same basic principles of VSEPR theory that have
been described can be used to determine the
geometry of several additional types of molecules,
such as AB2E, AB2E2, AB5, and AB6.
• Treat double and triple bonds the same way as
single bonds.
• Treat polyatomic ions similarly to molecules.
• The next slide shows several more examples of
molecular geometries determined by VSEPR
theory.
VSEPR and Molecular
Geometry
Chapter 6
Section 5 Molecular Geometry
VSEPR and Molecular
Geometry
VSEPR Theory
• Sample Problem F
a. Use VSEPR theory to predict the shape of a
molecule of carbon dioxide, CO2.
b. Use VSEPR theory to predict the shape
of a chlorate ion, ClO3 .
VSEPR Theory
• Sample Problem F Solution
a. Draw the Lewis structure of carbon dioxide.
O
•
C
O
There are two carbon-oxygen double bonds and
no unshared electron pairs on the carbon atom.
•
This is an AB2 molecule, which is
•
linear.
VSEPR Theory
• Sample Problem F Solution, continued
b. Draw the Lewis structure of the chlorate ion.
Cl
O O O
•
There are three oxygen atoms bonded to the central
chlorine atom, which has an unshared electron pair.
•
This is an AB3E molecule, which is
•
trigonal-pyramidal.
Explain
•
•
•
Click on the link
below and wait for
the teacher to give
you the link.
Activity 1:
https://nearpod.com/
Activity 2: in MS forms
Differentiated strategy (in process)
(Note: students can
choose the activities
according to their choice.)
Section 5: Mollecular geometry