Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction...
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Transcript of Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction...
![Page 1: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/1.jpg)
Unit 10: Chemical Bonding
Section 2: Molecular Geometry
![Page 2: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/2.jpg)
As molecules form…
Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces.
Multiple Bonds – occur in covalent bonds when atoms share more than one electron. Double Bond – atoms
share 2 electrons Triple Bond – atoms share
3 electrons
![Page 3: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/3.jpg)
Bond Strength vs Bond LengthThe more bonds between 2 atoms,
the stronger the bond.The more bonds between atoms, the
shorter the length of the bonds become
Bond Strength Single Bond < Double Bond < Triple Bond
Bond Length Single Bond > Double Bond > Triple Bond
![Page 4: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/4.jpg)
VSEPR Theory – “valence-shell electron-pair repulsion”
States that repulsion between the sets of valence electrons causes sets to be placed as far apart as possible. Electrons have the same charge, which
causes them to repel each other as far as possible
Leads to unique angles between atoms in the molecule.▪ Bond Angle – Angle made between two
adjacent atoms in a molecule
![Page 5: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/5.jpg)
VSEPR Theory
Bending of molecules leads to one of these molecular shapes… Linear Trigonal-planar Tetrahedral Bent Trigonal-pyramidal Trigonal-bipyramidal Octahedral
![Page 6: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/6.jpg)
Chart of Molecular shapes and corresponding bond angles
![Page 7: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/7.jpg)
Determining Polarity of a Molecule
A molecule may be polar or non-polar, just like the individual covalent bonds You must consider 2 things when
determining polarity of a molecule▪ 1) The polarity of the individual bonds in the
molecule▪ 2) The shape or geometry of the molecule
![Page 8: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/8.jpg)
Non-Polar Molecules
There are 3 possible outcomes If all bonds are non-polar, then the whole
molecule is non-polar regardless of its shape
If there is symmetry in the molecule so that the polarity of the bonds cancels out, then the molecule is non-polar▪ O=C=O The carbon-oxygen bond is a polar
bond, but because they are exactly opposed to each other, the molecule is overall non-polar
![Page 9: Section 2: Molecular Geometry. Forces draw the atoms closer together. These forces of attraction are called Intermolecular Forces. Multiple Bonds.](https://reader036.fdocuments.in/reader036/viewer/2022082713/5697bfc71a28abf838ca7eb4/html5/thumbnails/9.jpg)
Polar Molecules
If there are polar bonds but there is no symmetry such that they cancel each other out, the overall molecule is polar▪ Water is a typical example of this. The two O-
H bonds are oriented in a V-shape, and so the don't cancel out▪ Similarly, CH3Cl is also polar. It is the same
shape as CCl4 (see above), but now it doesn't have the same symmetry because there is only one C-Cl bond and the bonds don't cancel out anymore