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Archive – Q3 week 4 – 19-20

Week of 2/24 – 2/28 –   Remember to Refresh this page every time you open!

Monday – 2/24 – period 2 – 
 
1. Compared salts, Molecular, Metallic compounds through the conductive demos and animation.
    Used the more advanced understanding of electrons shielding or Z, Zeff to demonstrate how these compounds  
   differ.
    – properties based on crystal formation, ions, molecules, free electrons
2. Ionic Properties Demonstration-
3. Molecular Polarity Dem0 – 
                              period 3/4 –
 
1. Compared salts, Molecular, Metallic compounds through the conductive demos and animation.
    Used the more advanced understanding of electrons shielding or Z, Zeff to demonstrate how these compounds  
   differ.
    – properties based on crystal formation, ions, molecules, free electrons
2. Ionic Properties Demonstration-
3. Molecular Polarity Dem0 – 
 
4. Hot Air Balloons
Class Notes on the limitations of the Valance Bond Theories:
 
Valence bond theories that we learned:
1: Covalent bonds – sigma, pi bonding
2: VSEPR theory – (electron orbitals repelling to form equidistance stable geometries)
3: Lewis Dot structures
4. Hybridization
 
 
Our valence bond theories = hybridization, VSEPR, Lewis dot diagrams have limitations as we have seen.  How does the chlorate ion have resonance if it is sp3 hybridized and there are no un-hybridized p orbitals to pi bond with?
 
Remember that dots on a piece of paper can give us so much information for many molecules some complex but some our rules of formal charges that help guide us to the best structure guide us to structures that actually do not exist based on their properties found experimentally!
 
Here is an example of the sulfate ion, SO4-2
 
THE LEWIS DIAGRAM BELOW REPRESENTS THE BEST LEWIS DOT STRUCTURE BASED ON FORMAL CHARGES.  Below each sulfur has a Formal charge of ZERO!
Above is what our valence bond theory predicts using the rules of Formal Charges and etc.  THIS IS NOT WHAT WE FIND experimentally!!! Actually the lewis diagrams that we find from experimental evidence looks like the following.
 
The sulfur below has a Formal Charge of +2 and yet it is the structure we identify experimentally!
 
WHAT???  How can it exist more like this structure when clearly is breaks the rules of Formal Charges (+2) on the Sulfur atom?  Actually the charge is measured to be +1.77 on the sulfur in experiments.  What gives?  The bonding is neither covalent nor ionic it is something in between.. 
 
So we are at the end or the limits of this valence bond theory. We were were always going to be limited by a theory that treats electrons as dots when we have learned from electrons exist as waves!!!
 
So lets learn a new theory that picks up where valance bond theory leaves off.  It is called MO theory or molecular orbital theory and it treats electrons as waves!
 
Monday 2/24 – Homework: 
 
1. READ CLASS NOTES ABOVE FIRST!
 
2:  Watch the Lecture below on MO (molecular orbital theory) . You are going back to MIT! You will only need about the first 30 minute of the video.
3.  Complete the form below:
 

MO Theory Form 1920

 

 
              

MO orbital Theory Presentation:

MO Conjugated Theory

 
Today’s demos:
 
Electrolyte (salts or ionic compounds properties) vs. Metallic, and Molecular

 

Molecular polarity demo:
Molecular Conductivity Animation:
Molecular Polarity Animation:
 
End of Monday..

Tuesday – 2/25 – period  2/3 – 
 
1.  Review the Class Notes posted Monday- complete the discussion that valence bond theory although great in predicting the properties of so many compounds, does NOT predict and help explain all molecules.  There must be another theory.  That theory is MO theory.
 
2. Homework Review of the MO Theory Form:
 
MO Theory Form 1920 – Key p.pdf
View Download
3. MO theory – digital notes on linked presentation- “MO Bonding” – NOT SURE IF I WILL DO NEXT  YEAR – might be more effective to print out diagrams and students fill in.
      I linked every student a MO presentation to annotate and 
– completed the presentation that students annotated to.
– students completed the nitrogen and Oxygen worksheet in class with me.
– discovered that oxygen will have 2 lone pairs in the anti-bonding orbital that makes O2 paramagmetic.
– discovered the small gap between the anti- bonding orbitals is the reason oxygen is light blue.
 
isolated liquid oxygen/paramagnetic demo.
bonding 5 MO Yo!.pdf
View Download
 
bonding 5 MO Yo! complete key.pdf
View Download
 
Selected correlation graphs (Li2 – C2) – These were in the student presentation “MO Bonding “
bonding 5a MO Yo classwork!.pdf
View Download
 
Used this worksheet after the “MO Bondng”
bonding 5 MO Yo! oxygen and nitrogen.pdf
View Download
                                     period 4 – 
 
1. Review of why we need MO theory
2. Homework Review of the MO Theory Form:
 
MO Theory Form 1920 – Key p.pdf
View Download
3:  Modeled some MO diagrams/ Bond order determination
4 : MO theory – digital notes on linked presentation- “MO Bonding” 
     (did not get to this today..)
    
 
The making of liquid oxygen:
 
Liquid Oxygen Demonstration:
Liquid Oxygen is Paramagnetic: (only MO explains this!)
2/25 Tuesday Homework- 
 
*Remember that higher the bond order, shorter the bond distance, and higher the bond enthalpy (energy needed to break the connection between atoms).
1:  Complete the bonding 5 MO Yo! complete key.pdf worksheet and review with the key below or lecture below the form below. Period 4 will need the lecture as we had less time in class.
 
bonding 5 MO Yo! complete key.pdf
View Download
 
2: View lecture on Gap theory and complete form below: (best out of 2 attempts!)
 
Lecture on  bonding 5 MO Yo!.pdf worksheet: 
Lecture on Gap Theory:
Form on Gap theory (must watch lecture / and view slides on Gap Theory first):
End Tuesday!

 
Wednesday- 2/26 – period  2 – 
1: Review MO diagrams N2 and N2+ –  I modeled both on first side.
    – Determined the BO for both
    – Compared Bond lengths and bond energies for both using their respective Bond Energies
 
MO – N2 vs N2+.pdf
View Download
 
 
2. Reviewed the Homework Form:
 
Gap or Band Theory Form 1920 – Key p.pdf
View Download
       Used the Types of solids worksheet to start identifying the type of solid
        Network Solids – Covalently bonded crystal structure – 
 
                                    –  we saw graphite – C (s) and diamond (C) are  examples
 
We should know how to identify the band gap diagrams of the metallic solids, network, and molecular solids.
Types of Solids.pdf
View Download
 
Types of Solids key.pdf
View Download
 
bonding 5 MO Yo! oxygen and nitrogen.pdf
View Download
2: Review Gap Theory/ Chromophores / Crystal Field Splitting
3:  Chromophores vs Crystal Field theory
                                 
                                   period 3/ 4 – 
1: Review MO diagrams N2 and N2+ –  I modeled both on first side.
    – Determined the BO for both
    – Compared Bond lengths and bond energies for both using their respective Bond Energies
       Used the Types of solids worksheet to start identifying the type of solid
 
MO – N2 vs N2+.pdf
View Download
2. Reviewed the Homework Form:
 
Gap or Band Theory Form 1920 – Key p.pdf
View Download
 Network Solids – Covalently bonded crystal structure – 
 
                                    –  we saw graphite – C (s) and diamond (C) are  examples
 
We should know how to identify the band gap diagrams of the metallic solids, network, and molecular solids.
 
3. REview Gap Theory /Chromophores/ Crystal field theory
4:  Chromophores vs Crystal Field theory
                            
Today’s or Tomorrow’s Demo:
2/26 – Wednesday Homework:   – 2 parts!
1. Please read my notes below:
                                                                                                                   NEW!
 Ionic Solids Molecular solids     Network solids   Metallic Solids
 crystals of ions Molecules!!! crystals of covalent bonds crystals of nuclei in a sea of mobile electrons
Ex:  NaCl, NaNO3, NH4Cl Ex: H2O, CH4, C6H12O6     Ex: SiO2, C (s)graphite   Ex: Ni, Cu, Any metal element
 continuous ionic bonds    IMF depending on polarity   continuous covalent bonds              metallic bonds
 Chromophores – pi stacking if conjugated

  Non Chromophore  –

  Crystal field splitting
 Conductive if in (l) or (aq)   Non conductive      *Non conductive            Conductive
   high melting points  
     breaking ionic bonds
   Low Melting points
breaking IMF not Bonds!  
   high melting points
 breaking covalent bonds
   high melting points
   breaking metallic bonds
Network solids are the RARE CASE when some molecular compounds make continuous covalent bonds in their crystals.  Diamond and Graphite are examples.  Most molecular solids are held by IMF. *Graphite is the only Network solid that conducts due to the delocalization of electrons throughout its crystal.
 
IMF = Intermolecular Forces – ATTRACTIVE forces that hold molecules together
 
Molecular solids have the lowest melting points because when you give them heat you are separating molecules HELD TOGETHER BY ATTRACTIVE FORCES (IMF) that are only a fraction of the BOND Energy of Covalent, Ionic, or Metallic BONDs!  It takes less energy to separate molecules held together by attractive forces than it does to separate atoms or ions (breaking bonds).
 
Remember when we made the Slime (Cross-Linked Polymer)?  The long strands of the top and bottom molecules are held by the middle molecule attracting them. Notice the dashed lines in between the three molecules shown that represent the attractive forces.  Each different molecule is circled. These dashed lines are Intermolecular Forces (IMF’s) that are keeping this SLIME together as a solid.  They are written as dashed lines so not to confuse them with bonds. Because this solid is held by IMF which are much weaker than bonds you can imagine that it would not take much heat to “melt” your Slime. It would have a very low melting point.
 

Since we are breaking only attractive forces AND NOT BONDS heating this solid would be a PHYSICAL Change as the chemical formulas (of the individual molecules) would not change!

 
All phase changes (ex. melting, freezing) of molecular compounds are always physical changes!!!!
 
                                                H2O (s)  —-> H2O (l)  —-> H2O (g) 
 
                                                               Ice     —->  water    —->  steam
 
We are only separating the attractive forces between the molecules and thus the chemical formula does not change.
 
In our copper Iodine lab earlier in the year why did the Iodine sublime?
                                                                        I2 (s)  ——>   I2 (g) 
 
Because Iodine is a molecular solid with a low melting (sublimation) point due to the weak attractive keeping iodine as a solid.
 
2. Complete the Types of Solids.pdf worksheet and review with the key below.
Types of Solids.pdf
View Download
 
Types of Solids key.pdf
View Download
 
THERE IS NO FORM TONIGHT!
End Wednesday..

Thursday – 2/27 – period  2/3 –   
 
1.  Complete Gap theory with Solids worksheet – Review of Network Solids
 
Types of Solids Key New 1718 p.pdf
View Download
 
2.  IMF’s  Lesson – Attractions That keep molecular compounds together
 
            a) Discussion of LDF’s, dipolar forces, and H- Bonds
 
3.  Worked on and completed Classwork worksheet: IMF comparison worksheet 1819.pdf
IMF comparison worksheet 1819.pdf
View Download
 
IMF comparison worksheet 1819 KEY.pdf
View Download
 
Intermolecular Attractions Presentation:
                                            period 4  –
1.  Complete Gap theory with Solids worksheet – Review of Network Solids
 
Types of Solids Key New 1718 p.pdf
View Download
 
2.  IMF’s  Lesson – Attractions That keep molecular compounds together
 
            a) Discussion of LDF’s, dipolar forces, and H- Bonds
3.  Started Classwork worksheet: IMF comparison worksheet 1819.pdf
Will complete with me using lecture that will posted later.
 

IMF comparison worksheet 1819.pdf
View Download
 
IMF comparison worksheet 1819 KEY.pdf
View Download
 
Why would N2 (l) be a great
 liquid to use to create a large amount of vapor pressure?
 
Thursday – 2/28 Homework: 
*Please pay attention for your homework instructions by class!
1:  Period 2/3 : View lecture on Intermolecular attractions – if needed- 
1:  Period 4:  You will need to complete the Lecture below starting at 17:22.
 
2Period 4: Complete the 1st side of the IMF comparison worksheet 1819.pdf worksheet using the 
      Lecture below for the worksheet.  The key is available for your viewing pleasures.
 
IMF comparison worksheet 1819.pdf
View Download
IMF comparison worksheet 1819 KEY.pdf
View Download
IMF Comparison Review –  Lecture:
 
 
2:  Period 1 – Complete form on intermolecular attractions (best out of 2 submissions).
3:  Period 4 – Complete form on intermolecular attractions (best out of 2 submissions).
 
Lecture on intermolecular attractions (started or completed in class):
Intermolecular attractions form:
This form is on auto-reply and you have 2 submissions that are due by tomorrow morning.
 
End Thursday

Friday – 2/29 – Leap year!
 
Period 2 – 
1. Review Homework Form – Review the concept of solubility/miscibility with water
                                               
Intermolecular Attractions Form 1920 – Key pp.pdf
View Download
2. RAT QUIZ on IMF’s
 
Period 3/4 – 
 
1. Review Homework Form – Review the concept of solubility/miscibility with water
 
                                                    – Like dissolves Like really means?? 
 
2. Mini – lesson on Ideal solutions- 
 
3. Complete – IMF comparison worksheet 1819.pdf worksheet – front and back
 
IMF comparison worksheet 1819.pdf
View Download
 
IMF comparison worksheet 1819 KEY.pdf
View Download
 
4. RAT Quiz on IMF’s
 
 
2/29 – Friday – HOMEWORK – Bonding Test 3 – TEST MONDAY!
 
 Bonding TEST 3 – MO diagrams, Band theory, crystal field splitting, chromophores, intermolecular attractions, types of compounds.
1 : Study your forms (MO Form 1),  (Band/Gap Theory) , (IMF form).
     You have key’s for each of them!
 
(MO Form 1):
MO Theory Form 1920 – Key p.pdf
View Download
(Band/Gap Theory):
Gap or Band Theory Form 1920 – Key p.pdf
View Download
 
(IMF form):
Intermolecular Attractions Form 1920 – Key pp.pdf
View Download
 
2.  Complete the IMF comparison 2 worksheet.pdf for more practice on IMF’s
      with the key or the video below it.
 
IMF comparison 2 worksheet.pdf
View Download
IMF comparison 2 worksheet Key.pdf
View Download
IMF comparison 2 worksheet.pdf lecture:  
This was a lecture made with the older version of the worksheet that you have.
 
3.  Review the classwork worksheet that we did in class Thursday/Friday.
IMF comparison worksheet 1819.pdf
View Download
 
IMF comparison worksheet 1819 KEY.pdf
View Download
IMF Comparison Review –  Lecture:
 
4. Review the Friday’s RAT quiz with the Key below:
 
IMF RAT 1718 KEY p.pdf
View Download
5.  The presentations that were used this week:
 
MO orbital Theory Presentation:

MO Conjugated Theory

 
Intermolecular Attractions Presentation:
This was a another great week!  Great Job! Thanks for your hard work!!
 
End of week 4!