# Molecular Geometry and Bonding Theories - PowerPoint PPT Presentation

Loading...

PPT – Molecular Geometry and Bonding Theories PowerPoint presentation | free to view - id: 755992-MmMzN

The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

## Molecular Geometry and Bonding Theories

Description:

### Chapter 8 Molecular Geometry and Bonding Theories – PowerPoint PPT presentation

Number of Views:113
Avg rating:3.0/5.0
Slides: 30
Provided by: Pears169
Category:
Tags:
User Comments (0)
Transcript and Presenter's Notes

Title: Molecular Geometry and Bonding Theories

1
Chapter 8
• Molecular Geometry and Bonding Theories

2
Molecular Shapes
• The shape of a molecule plays an important role
in its reactivity.
• By noting the number of bonding and nonbonding
electron pairs, we can easily predict the shape
of the molecule.

Figure 8.2
3
(No Transcript)
4
CH4 , C , H2O (SO4)-2 , (SiO4)-4
(PO4)-3 , CCl2F2
5
(No Transcript)
6
What Determines the Shape of a Molecule?
• Simply put, electron pairs, whether they are
bonding or nonbonding, repel each other.
• By assuming the electron pairs are placed as far
as possible from each other, we can predict the
shape of the molecule.

7
Valence Shell Electron Pair Repulsion Theory
(VSEPR)
• The best arrangement of a given number of
electron domains is the one that minimizes the
repulsions among them.

8
(No Transcript)
9
Electron Domains
• We can refer to the electron pairs as electron
domains.
• In a double or triple bond, all electrons shared
between those two atoms are on the same side of
the central atom. Therefore, they count as one
electron domain.

This molecule has four electron domains.
10
Electron-Domain Geometries
• These are the electron-domain geometries for two
through six electron domains around a central
atom.

Table 8.1
11
Electron-Domain Geometries
• All one must do is count the number of electron
domains in the Lewis structure.
• The geometry will be that which corresponds to
that number of electron domains.

Figure 8.6
12
Molecular Geometries
• The electron-domain geometry is often not the
shape of the molecule, however.
• The molecular geometry is defined by the
positions of only the atoms in the molecules, not
the nonbonding pairs.

Figure 8.6
13
Electron Domain Linear
• In this domain, there is only one molecular
geometry linear.
• NOTE If there are only two atoms in the
molecule, the molecule will be linear no matter
what the electron domain geometry is.

Table 8.2
14
Molecular Geometries
• Within each electron domain structure,
• there might be more than one molecular geometry.
• Given these examples, try and draw the electron
domain geometry for OH- ,
• The hydroxide ion.
• Once you try this,
• look at the notes for more chemical consequences
of these simple geometries.

Table 8.2
15
Electron Domain Trigonal Planar
• There are two molecular geometries
• Trigonal planar, if all the electron domains are
bonding
• Bent, if one of the domains is a nonbonding pair.

Table 8.2
16
Electron Domain Tetrahedral
• There are three molecular geometries
• Tetrahedral, if all are bonding pairs
• Trigonal pyramidal, if one is a nonbonding pair
• Bent, if there are two nonbonding pairs

Table 8.2
17
Electron Domain Trigonal Bipyramidal
• There are two distinct positions in this
geometry
• Axial (Apical if degenerate)
• Equatorial
• Name and draw the 4 possible degenerate
geometries.

Figure 8.8
18
Electron Domain Trigonal Bipyramidal
• Lower-energy conformations result from having
nonbonding electron pairs in equatorial, rather
than axial, positions in this geometry.

19
Electron Domain Trigonal Bipyramidal
• There are four distinct molecular geometries in
• this domain
• Trigonal bipyramidal
• Seesaw
• T-shaped
• Linear

Table 8.3
20
Electron Domain Octahedral
• All positions are equivalent in the octahedral
domain. There are three molecular geometries
• Octahedral
• Square pyramidal
• Square planar

Table 8.3
21
The Effect of Nonbonding Electrons and Multiple
Bonds on Bond Angles
• Nonbonding pairs are physically larger than
bonding pairs (all charge and virtually no mass
to constrain them).
• Therefore, their repulsions are greater this
tends to decrease bond angles in a molecule.

Figure 8.7
22
The Effect of Nonbonding Electrons and Multiple
Bonds on Bond Angles
• Double and triple bonds place greater electron
density on one side of the central atom than do
single bonds.
• Therefore, they also affect bond angles.
• For hazards and gas warefare read notes.

23
Shapes of Larger Molecules
• In larger molecules, it makes more sense to talk
about the geometry of a particular atom rather
than the geometry of the molecule as a whole.

24
(No Transcript)
25
Molecular Shape and Molecular Polarity
• If a molecule possesses polar bonds, it does not
mean the molecule as a whole will be polar.

Figure 8.11
26
Molecular Shape and Molecular Polarity
• By adding the individual bond dipoles, one can
determine the overall dipole moment for the
molecule.

Figure 8.12
27
Molecules Containing Polar Bonds
Figure 8.13
28
F12
Ozone-depleting gas trends
F22
29
Chapter 8 End of Part 1
• Molecular Shapes
• Electron Domain Shapes
About PowerShow.com