Covalent Bonding - Mr. Michael's Website -...
Transcript of Covalent Bonding - Mr. Michael's Website -...
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Chapter 8Covalent Bonding
8.1 Molecular Compounds8.2 The Nature of Covalent Bonding
8.3 Bonding Theories
8.4 Polar Bonds and Molecules
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Molecular Shape
What information does a structural formula give you?
Structural formula
It tells us… 1) Which atoms are
bonded to which
2) Whether single, double or triple bonds are used.
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Molecular Shape
A structural formula is two-dimensional, so it does not give us a true representation of the arrangement of atoms. Molecules are 3-D!
Structural formula
3-D Model
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Molecular Shape
Why is the shape of a molecule VERY important?
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The shape of a molecule helps us predict some of its properties.
If water wasn’t “bent” it would have totally different properties.
Molecular Shape
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VSEPR Theory
• What is it? The theory scientist use to predict the shape of molecules.
VSEPR Theory
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VSEPR Theory(What we use to predict the shapes of molecules)
• First concept: Electron Domain
• Page 38-39, Questions 1-10.
VSEPR Theory
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VSEPR Theory: Checkpoint 1
How many electron domains?
VSEPR Theory
4 electron domains
(2 bonding, 2 nonbonding)
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VSEPR Theory: Checkpoint 1
How many electron domains?
VSEPR Theory
3 electron domains
(2 bonding, 1 nonbonding)
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VSEPR Theory: Checkpoint 1
How many electron domains?
VSEPR Theory
2 electron domains
(2 bonding, 0 nonbonding)
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VSEPR Theory: Checkpoint 1
How many electron domains?
VSEPR Theory
6 electron domains
(6 bonding, 0 nonbonding)
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VSEPR Theory: Checkpoint 1
True or False? All covalent bonds (single, double or triple) count as 1 electron domain.
TRUE
VSEPR Theory
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VSEPR Theory: Checkpoint 1
True or False? A non-bonding pair of electrons counts as 1 electron domain.
TRUE
VSEPR Theory
Also called a “lone pair”
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VSEPR Theory: Checkpoint 1
Electron domains (attract/repel) each other.
Repel
VSEPR Theory
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VSEPR Theory (what we use to predict 3-D shapes of molecules)
Valence-Shell Electron-Pair Repulsion theory
• All electron domains around an atom will be positioned as far apart as possible in three-dimensional space.
VSEPR Theory
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VSEPR Theory
• Second concept: Repulsions lead to 3-D Shapes
• Page 39-40, Questions 11-17.
VSEPR Theory
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VSEPR Theory: Checkpoint 2
Why is it possible to get larger angles separating electron domains in three-dimensions versus two-dimensions?
There is more space in three-dimensions than in two-dimensions.
VSEPR Theory
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VSEPR Theory: Checkpoint 2
True or False?Lone pairs and bonding pairs repel each other equally.
False. Lone pairs repelmore strongly.
VSEPR Theory
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VSEPR Theory: Checkpoint 2
Which would repel each other the most?a)Two bonded pairs.b)A bonded pair and a lone pair.c)Two lone pairs.
Two lone pairs.
VSEPR Theory
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Due Today: Finish the worksheet (#1-20)
Homework #1 VSEPR Homework on Page 42
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VSEPR Theory
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VSEPR Theory
2 electron domains 3 electron
domains4 electron domains
LinearTrigonal planar
Tetrahedral
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Trigonal planar
120o
VSEPR Theory
Bent
< 120o
3 electron domains
The name of the shape is determined by looking at the ATOMS only.
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Tetrahedral
109.5o
VSEPR Theory
4 electron domains
A tetrahedron is a 3-D shape with 4 sides
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Trigonal pyramid
107o
VSEPR Theory
4 electron domains
The name of the shape is determined by looking at the ATOMS only.
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Bent
104.5o
VSEPR Theory
4 electron domains
The name of the shape is determined by looking at the ATOMS only.
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Trigonal bipyramid
120o, 90o
VSEPR Theory
5 electron domains
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Seesaw
120o, 90o
VSEPR Theory
5 electron domains
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T-shaped
90o
VSEPR Theory
5 electron domains
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Octahedral
90o
VSEPR Theory
6 electron domains
An octahedron is a 3-D shape with 8 sides.
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Square pyramid
90o
VSEPR Theory
6 electron domains
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Square planar
90o
VSEPR Theory
6 electron domains
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What causes valence-electron pairs to stay as far apart as possible?
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What causes valence-electron pairs to stay as far apart as possible?
The repulsion between electron pairs due to their negative charges causes valence-electron pairs to stay as far apart as possible.
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Shared electrons and the valence electrons that are not shared affect the shape of a molecular compound, as the valence electrons stay as far apart from each other as possible.
BIG IDEA
Bonding and Interactions
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