intermolecular attractions
DESCRIPTION
Intermolecular Attractions. Bonding and VSEPR Theory Structures of Solids and liquids. Electron Dot (Lewis) Diagrams Explain Chemical Bonding. Chemical bonds – occur when electrons are transferred or shared by elements so that they each become more stable. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/1.jpg)
BONDING AND VSEPR THEORY
STRUCTURES OF SOLIDS AND LIQUIDS
Intermolecular Attractions
![Page 2: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/2.jpg)
CHEMICAL BONDS – OCCUR WHEN ELECTRONS ARE TRANSFERRED OR SHARED BY ELEMENTS SO THAT THEY EACH BECOME MORE STABLE
Electron Dot (Lewis) Diagrams Explain Chemical
Bonding
![Page 3: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/3.jpg)
How many electrons do most atoms want in their outer energy level to be stable?
0 1 2 6 8 18
17% 17% 17%17%17%17%
1. 02. 13. 24. 65. 86. 18
![Page 4: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/4.jpg)
Bonds that form between two nonmetals are which type?
Ionic
Covalent
Metallic
33% 33%33%1. Ionic2. Covalent3. Metallic
![Page 5: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/5.jpg)
Drawing Electron Dot Diagrams
Electrons usually stay in pairs when bonded.
Bonding pairs – pair of electrons that form the bond
- can be represented as a line segment
Lone (or unbonded) pairs – pairs of electrons that are not involved in bonds and are shown as dots
![Page 6: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/6.jpg)
How many bonding pairs are in the following compound?
1 2 3 4 6 9 18
14% 14% 14% 14%14%14%14%1. 12. 23. 34. 45. 66. 97. 18
![Page 7: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/7.jpg)
How many lone pairs are in the following compound?
1 2 3 4 6 9 18
14% 14% 14% 14%14%14%14%1. 12. 23. 34. 45. 66. 97. 18
![Page 8: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/8.jpg)
How many bonding pairs and lone pairs are in the following compound?
6 bonding pair...
12 bonding pai...
12 bonding pai...
6bonding pairs
...
0% 0%0%0%
1. 6 bonding pairs, 18 lone pairs
2. 12 bonding pairs, 18 lone pairs
3. 12 bonding pairs, 36 lone pairs
4. 6bonding pairs, 6 lone pairs
![Page 9: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/9.jpg)
Drawing Electron Dot Formulas for Compounds
Exceptions: Hydrogen only needs 2 electrons (1 bond)
Boron tends to need only 6 electrons (3 bonds)
Single atoms go in the center
If more than one single atom, middle atom central atom
![Page 10: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/10.jpg)
Draw the electron dot formula. Then state how many bonding and unbonding pairs are present.
A) NBr3
B) Water
C) Chlorite ion (ClO2- )
D) CF2Cl2
![Page 11: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/11.jpg)
Multiple Bonds
If there are not enough electrons to form full octets, multiple bonds may need to be formed.
![Page 12: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/12.jpg)
Draw the electron dot formula
E) O2
F) CO2
![Page 13: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/13.jpg)
Resonance Structures
If there are more than one possibility, resonance structures are drawn.
Resonance structures show possible locations of the bonds. In reality the electrons exist as an average of the two structures – splitting time equally between them.
![Page 14: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/14.jpg)
Resonance Example
Each resonance structure is shown followed by the combination with the double bonds shown with a dotted line as one of the bonds.
![Page 15: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/15.jpg)
Draw the electron dot formulas including resonance structures
G) SO2
H) N2O
![Page 16: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/16.jpg)
What is the name of the property that describes the tendency of an atom to attract electrons when bonded to another atom?
Ioniza
tion ene...
Conductivit
y
Electr
onegativ..
.
Metallic
Chara...
Bond length
20% 20% 20%20%20%
1. Ionization energy
2. Conductivity3. Electronegativit
y4. Metallic
Character5. Bond length
![Page 17: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/17.jpg)
Classifying Bond Types
Chemical bonds can be classified by how much the bonded electrons are shared or are not shared by the elements involved.
• Electronegativity: The ability of one atoms in a molecule to attract electrons to itself.
• Wolfgang Pauling set electronegativities on a scale from 0.7 (Cs) to 4.0 (F).
• Electronegativity increases • across a period and • down a group.
![Page 18: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/18.jpg)
Electronegativities of Elements
Electronegativity
![Page 19: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/19.jpg)
![Page 20: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/20.jpg)
Bond Classification based on Electronegativity Difference
As the difference in electronegativity increases, electrons are less equally shared and become more polar.
![Page 21: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/21.jpg)
Type of Bonds Electronegativity Difference
Nonpolar covalent
Polar covalent
Ionic
x ≤ 0.4
0.4 < x < 1.8
x ≥ 1.8
Bond Classification based on Electronegativity Difference
![Page 22: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/22.jpg)
![Page 23: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/23.jpg)
Classify the bond between the following elements: Cl and Cs
Ionic
Polar Covale
nt
Nonpolar Cova
l...
0% 0%0%
1. Ionic2. Polar Covalent3. Nonpolar
Covalent
![Page 24: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/24.jpg)
Classify the bond between the following elements: C and H
Ionic
Polar Covale
nt
Nonpolar Cova
l...
0% 0%0%
1. Ionic2. Polar Covalent3. Nonpolar
Covalent
![Page 25: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/25.jpg)
Classify the bond between the following elements: N and O
Ionic
Polar Covale
nt
Nonpolar Cova
l...
0% 0%0%
1. Ionic2. Polar Covalent3. Nonpolar
Covalent
![Page 26: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/26.jpg)
INTERMOLECULAR FORCES
Interactions between Molecules
![Page 27: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/27.jpg)
Polarity of a Compound
Like bonds, compounds themselves can also be classified as polar or nonpolar.
Polarity is based on: Difference in electronegativity of atoms within a
compound Symmetry of the compound
![Page 28: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/28.jpg)
Nonpolar Compounds
- Diatomic molecules are always nonpolar. (ex. F2)
- Also, compounds that are totally symmetric may be nonpolar as well. (ex. CCl4)
![Page 29: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/29.jpg)
Nonpolar Compound – the bonds are polar but the dipoles cancel out since the compound is symmetrical (tetrahedral)
![Page 30: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/30.jpg)
Nonpolar Compound – the bonds are polar but the dipoles cancel out since the compound is symmetrical (linear)
![Page 31: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/31.jpg)
Polar Compounds
Polar compounds have one side of the compound that is more positive and another side that is more negative.
![Page 32: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/32.jpg)
Polar Compounds
![Page 33: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/33.jpg)
Polar Compounds
![Page 34: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/34.jpg)
Polar Compounds
![Page 35: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/35.jpg)
BF3 = Polar or Nonpolar
1 2
0%0%
1. Polar2. Nonpolar
![Page 36: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/36.jpg)
![Page 37: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/37.jpg)
CH3F = Polar or Nonpolar?
1 2
0%0%
1. Polar2. Nonpolar
![Page 38: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/38.jpg)
![Page 39: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/39.jpg)
CF4 = Polar or Nonpolar?
1 2
0%0%
1. Polar2. Nonpolar
![Page 40: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/40.jpg)
Br2 = Polar or Nonpolar
1 2
0%0%
1. Polar2. Nonpolar
![Page 41: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/41.jpg)
PBr3 = Polar or Nonpolar
1 2
0%0%
1. Polar2. Nonpolar
![Page 42: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/42.jpg)
Intermolecular Forces
Intermolecular Forces are forces that exist between two molecules that hold them together.
Intermolecular Forces are caused by charge differences and polarity (because positive and negatives attract)
The stronger the polarity, the stronger the attraction between molecules.
![Page 43: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/43.jpg)
Intermolecular Forces
The stronger the polarity, the stronger the attraction between molecules.
The strength of the attraction between molecules determines properties such as: Boiling point Melting point Surface tension Cohesion Capillary action
![Page 44: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/44.jpg)
Types of Intermolecular Forces
Three major types of intermolecular forces: Dipole-Dipole Interactions
Hydrogen Bonds
Dispersion Forces
![Page 45: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/45.jpg)
Dipole-Dipole Interaction
Occurs in polar molecules.
Positive pole of one molecule is attracted to the negative pole of the next molecule.
![Page 46: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/46.jpg)
Hydrogen Bonds
Occurs in polar molecules when the hydrogen atom is attracted to the more electronegative nitrogen, oxygen, or fluorine atom of another molecule.
![Page 47: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/47.jpg)
![Page 48: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/48.jpg)
Dispersion Forces
Dispersion forces are the weakest type of intermolecular forces because they exist between nonpolar molecules.
Usually, the electrons are shared equally. But because electrons are constantly moving, sometimes a temporary dipole forms when all the electrons are on one side of the molecule.
This temporary dipole would cause an attraction with another temporary dipole.
![Page 49: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/49.jpg)
Summary of Intermolecular Forces (from strongest to weakest)
![Page 50: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/50.jpg)
What kind of intermolecular force would exist in H2O?
1 2 3
0% 0%0%
1. Hydrogen bonding
2. Dipole-Dipole3. Dispersion
![Page 51: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/51.jpg)
What kind of intermolecular force would exist in PCl3?
1 2 3
0% 0%0%
1. Hydrogen bonding
2. Dipole-Dipole3. Dispersion
![Page 52: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/52.jpg)
What kind of intermolecular force would exist in Br2?
1 2 3
0% 0%0%
1. Hydrogen bonding
2. Dipole-Dipole3. Dispersion
![Page 53: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/53.jpg)
What kind of intermolecular force would exist in NH3?
1 2 3
0% 0%0%
1. Hydrogen bonding
2. Dipole-Dipole3. Dispersion
![Page 54: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/54.jpg)
Melting and Boiling Points
In order to melt or boil a substance, intermolecular forces must be broken.
Therefore, weaker intermolecular forces require less energy and have lower melting and boiling points.
Therefore, stronger intermolecular forces require more energy and have higher melting and boiling points.
![Page 55: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/55.jpg)
Which type of intermolecular force would have the lowest boiling point and exist as a gas at room temperature?
1 2 3 4 5
0% 0% 0%0%0%
1. Ionic Bonds2. Dispersion
Forces3. Hydrogen
Bonds4. Covalent Bonds5. Dipole-Dipole
attractions
![Page 56: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/56.jpg)
Which type of intermolecular force would have the highest melting point and always exist as a solid at room temperature?
1 2 3 4 5
0% 0% 0%0%0%
1. Ionic Bonds2. Dispersion
Forces3. Hydrogen
Bonds4. Covalent Bonds5. Dipole-Dipole
attractions
![Page 57: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/57.jpg)
Which compound would have the lowest boiling point and exist as a gas at room temperature?
1 2 3 4 5
0% 0% 0%0%0%
1. H2O2. N2
3. CuI2
4. CO2
5. LiF
![Page 58: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/58.jpg)
Which compound would have the highest melting point?
1 2 3 4 5
0% 0% 0%0%0%
1. NH3
2. NaBr3. F2
4. CO2
5. NH3
![Page 59: Intermolecular Attractions](https://reader033.vdocuments.net/reader033/viewer/2022042603/56815ff8550346895dcef6f5/html5/thumbnails/59.jpg)
Effects of Molecular Mass on Melting and Boiling Points
The higher molecular masses will have higher melting and boiling points because they have more electrons that form temporary dipoles.
Acts as the tiebreaker if the forces are the same types – highest mass has the strongest force (highest melting and boiling point).