Bonding Considerations The following PowerPoint presentation is a self directed study of...
-
Upload
harriet-chandler -
Category
Documents
-
view
218 -
download
0
description
Transcript of Bonding Considerations The following PowerPoint presentation is a self directed study of...
![Page 1: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/1.jpg)
The following PowerPoint presentation is a self directed study of additional bonding considerations. It includes information above and beyond the ionic and covalent bondingthat you have learned in class.
You are expected to review and study this PowerPoint on you own time.When you feel you are ready, ask your teacher for a handout that will testyour knowledge of these additional aspects of bonding nature.
![Page 2: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/2.jpg)
Let’s ReviewIONIC BONDSIONIC BONDS exist when one atom transfers
electron/s to another atom. Both atoms have attained a Noble Gas configuration.
COVALENT BONDS exist when two atoms share a pair of electrons between them in what is known as a SIGMA ()bond. It is also possible for atoms to share more than one pair of electrons. These multiple bonds are known as PI ()bonds. The atoms involved in bonding have attained a Noble Gas configuration.
![Page 3: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/3.jpg)
VSEPR Theory ExpandedConsider the tetrahedral sp3 hybrid. It
produces an atom with four bonding orbitals each separated by 109.5o.
However, this angle can be altered, in particular, by unshared electron pairs. Let’s consider two common examples of this phenomena.
![Page 4: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/4.jpg)
WaterThe bonding angle between the two Hydrogens in H2O with
its two unshared electron pair lobes on the Oxygen is 104.5o. WHY?
The two unshared pairs, are not confined (restricted) between the nuclei of two atoms.
Therefore, they are able to expand to a greater degree and “squeeze” together the bonds of the two Hydrogen atoms.
![Page 5: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/5.jpg)
AmmoniaThe bonding angle between the three Hydrogens in NH3
with its unshared electron pair lobe is 107o. WHY? The unshared pair on the Nitrogen is not confined
(restricted) between the nuclei of two atoms.Therefore, it is able to expand to a greater degree and
“squeeze” together the bonds of the three Hydrogen atoms.
![Page 6: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/6.jpg)
How can I see these angle changes for myself?
1) Using your Lewis structure directions, make a diagram of CH4 and NH3 and H2O.
2) Note the unshared pairs of electrons on the ammonia and water molecules.
3) Using the ball and stick sp3 models make models of methane, ammonia, and water.
4) Note that in the case of the ammonia and water there will be one and two holes respectively that aren’t filled. These are the unshared pairs. Fill them with gray sticks to represent the unshared electron pairs.
![Page 7: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/7.jpg)
I’m having trouble visualizing these molecules. What can I do?Methane: Note four sigma bonds with the H
atoms which complete the octet of the Carbon.
![Page 8: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/8.jpg)
I’m having trouble visualizing these molecules. What can I do?Ammonia: Note the three sigma bonds with
the H atoms. The lobe of unshared electrons are from the valence electrons of the N atom itself.
![Page 9: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/9.jpg)
I’m having trouble visualizing these molecules. What can I do?Water: Note the two sigma bonds with the H
atoms. The two lobes of unshared electrons are from the valence electrons of the O atom itself.
Note the two lobes of unshared electrons on the lower right of the water molecule.
![Page 10: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/10.jpg)
What have you learned so far?QUESTIONS:1) What are all four angles for a tetrahedron?2) What is the angle between the two H’s in a water molecule?3) What are the angles between three H’s in an ammonia
molecule?4) Why are the angles in water and ammonia less than a
tetrahedron?ANSWERS:1) 109.5o
2) 104.5o
3) 107o
4) The lobes of the unshared pairs expand, take up more space, and push the bonded atoms closer together.
![Page 11: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/11.jpg)
Bond Strength ~ INTRAMOLECULAR BONDS
COVALENT ~ Bonds within a single molecule
IONIC ~ Bonds within a single crystal
Bond strength is determined by BOND ENERGY, i.e. the amount of energy to break the bonds in Kilojoules per mole of bonds
RANK ~ Strongest to Weakest
1) Network Covalent Bonds
2) Ionic Bonds3) Metallic Bonds4) Polar Covalent Bonds5) Non-polar Covalent
Bonds
![Page 12: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/12.jpg)
NETWORK COVALENT SOLIDS
Examples: C (diamond), SiO2 (silica sand)Structural Particles: AtomsElectronegativity Difference: ZeroForces between Particles: Non-polar covalent
bondsProperties: Hard, very high-melting solids;
nonconductors; insoluble in common solvents
![Page 13: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/13.jpg)
Can I see a model of a diamond?Here it is: C-C
bonding!Here’s SiO2 for you
too! SiO2 is sand and
quartz
![Page 14: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/14.jpg)
IONIC BONDSExamples: NaCl (table salt), CaCO3 (calcite)Structural Particles: ions (cation and anion)Forces between Particles: Ionic bondsElectronegativity Difference: >1.7Properties: High melting points; conductors
in the molten state or water solution; usually soluble in water; insoluble in organic solvents
![Page 15: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/15.jpg)
Ionic Crystals can have many different shapes.Table Salt
Copper sulfate
Triphylite
![Page 16: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/16.jpg)
METALLIC BONDSExamples: (sodium), Fe (iron), Au (gold)Structural Particles: cations and mobile
electronsForces between Particles: Metallic bondsProperties: Variable melting points; conductors
in solid state; insoluble in common solvents
LEARN MORE ABOUT THE NATURE OF METALLIC BONDS BY CLICKING THIS LINK: www.ausetute.com.au/metallic.html
![Page 17: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/17.jpg)
A typical metal
![Page 18: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/18.jpg)
POLAR COVALENT BONDSExamples: NH3 (ammonia), HCl
(hydrochloric acid)Structural Particles: Polar moleculesForces between Particles: Polar covalent
bondsElectronegativity Differences: 0.2 – 1.7Properties: Generally higher melting points
and boiling points than non-polar molecules; more likely to be water- soluble
![Page 19: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/19.jpg)
NON-POLAR COVALENT BONDSExamples: H2 (hydrogen gas), CCl4 (carbon
tetrachloride)Structural Particles: Non-polar moleculesForces between Particles: Non-polar covalent
bondsElectronegativity Differences: 0 – 0.2Properties: Low melting and boiling points; often
gas or liquid at 25oC; insoluble in water; soluble in inorganic solvents
![Page 20: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/20.jpg)
![Page 21: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/21.jpg)
What have you learned so far?QUESTIONS:1) Intramolecular bonds are between what types of particles?2)What is bond energy? What unit is used?3) Rank the bond strength from highest to lowest.4) How are metallic bonds different from the other bonds?ANSWERS:
1) Within a single molecule (covalent compounds) & within a single crystal (ionic bonds)2) It is the energy to break a mole of bonds and the unit is kJ/mol.3) Coordinate covalent, ionic, metallic, polar covalent, non-polar covalent4) They involve a moving “sea of electrons.”
![Page 22: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/22.jpg)
Bond Strength ~ INTERMOLECULAR BONDS
These are bonds between molecules (covalent compounds).
Technically they are not bonds in the normal sense. Rather, they are attractive interactions.
The bond strength is measured in Kilojoules per mole of bonds.
Together these attractions are known collectively as van der Waals forces.
RANK ~ Strongest to Weakest
1) Hydrogen bonds2) Dipole – dipole
interactions3) Dipole – induced dipole
interactions4) Dispersion (London)
forces
![Page 23: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/23.jpg)
HYDROGEN BONDSA force exerted between an H atom bonded to an F,
O or N atom on one molecule and an unshared electron pair on the F, O or N atom on another molecule.
The H on the molecule behaves almost like a bare proton because of the high electronegativities of the F (4.0), O (3.5) and N (3.0).
The small size of the H atom allows the unshared pair of the F, O or N to approach very closely. NOTE: This only happens with these three non-metals with their small atomic radii.
H bonding creates relatively high melting and boiling points compared to the low molar masses.
![Page 24: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/24.jpg)
Water is affected by hydrogen bondingThe high surface tension of water is due to H
bonds.NOTE: H bonding creates higher melting and
boiling pointsWater, H2O,\; H bonds:
b.p. 100o C molar mass 18 g/mol
Methane, CH4; no H bonds:b.p. -161.6oC molar mass 16 g/mol
![Page 25: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/25.jpg)
DIPOLE-DIPOLE INTERACTIONSPolar molecules experience an asymmetrical
electronegativity difference higher than 0.2 across the molecule.
Such a molecule is called a dipole.The dipoles line up as close as possible, positive
end to negative endThere is an attractive force between adjacent
molecules. This is known as the dipole moment. Mr. Congdon’s Joke: What did the two dipoles say to each other? You got a moment?
![Page 26: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/26.jpg)
DIPOLE-INDUCED DIPOLE INTERACTIONSA permanent dipole molecule such as
Hydrogen fluoride (H-F) can “induce” (create) a temporary dipole moment in an adjoining non-polar molecule
The overall electron cloud of the molecule (or part of the molecule) will shift to create (+) and (-) poles
Note that these interactions are temporary and the non-polar molecule will shift its electron cloud position back to normal once the permanent dipole is no longer close
Hydrogen flouride
![Page 27: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/27.jpg)
DISPERSION (London) FORCESThese forces involve attractions between temporary
or induced dipoles in adjacent molecules.At a given instant, the electron cloud around a non-
polar molecule may shift from one side of the molecule to the other, thus inducing a dipole.
The temporary dipole induces a similar dipole in an adjacent non-polar molecule.
ALL molecules have dispersion forces. The strength of the forces depends on…..the number of electrons that make up the moleculeThe ease with which the electrons are dispersed to form
temporary dipoles
![Page 28: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/28.jpg)
London forces are responsible for holding much of your body together because of the many molecules involved. Have you every split your lip or your knee bumping into
something? OUCH! You exerted enough bond energy to break the London forces in
your lip or in your knee. Remember London forces are the weakest of the intermolecular
forces.
![Page 29: Bonding Considerations The following PowerPoint presentation is a self directed study of additional…](https://reader035.fdocuments.us/reader035/viewer/2022062601/5a4d1bfc7f8b9ab0599ec80d/html5/thumbnails/29.jpg)
Once you have reviewed this PowerPoint, see your instructor for an evaluative problem set.
1) You will be asked to fill out several questions related to this PowerPoint.
2) You may refer back to the PowerPoint at any time.
3) The evaluative problem set will also give you book references.
4) You will also be asked to evaluate this PowerPoint and offer suggestions.