Archive – AP Chem – Q3 – week 5 – 21-22

Q3: Week 5 – 3/7 – 3/11

Jump to: Tuesday, Wednesday, Thursday, Friday ^{______________________________________________________________}

3/7 – Monday – A Day – 2/3a Lab, 4

Main focus –

a) To Review sp2 hybridization, molecular and electron domain geometry.

b) To introduce sp3 hybridization.

c) To identify the electron and molecular geometries through VSEPR theory.

Period 2/3, 4:

1. Review the sp2 hybridization worksheet and form.

sp2 hybridization KEY p.pdf
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Hybridization Form 2 – key p.pdf – (weekend’s form key)
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2. sp, sp² , and sp³ – Began by filling out Hybridization Comparison chart for sp and sp2 only.

– began lecture of sp3 using sp3 hybridization worksheet

3. VESPR THeory – PHET

4. sp³ hybridization – use the “models” to show how methane is not planar.

Classwork:

Hybridization Comparison Chart Intro.pdf
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sp3 hybridization.pdf
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TODAY’s NOTES:

Octet Hybridization Table:

Although we say the bond angles of any sp3 hybridized molecule is 109.5 degrees that is not entirely true as the “Internuclear Distance of the electron lone pair will decrease if there is not a nucleus pulling it away from the central hybridized atom. The hybrid orbitals that contain the lone pair(s) are thus closer to the other hybrid orbitals and thus these hybrid orbitals repel the bonded hybrid orbitals into a smaller angle.

Notice the water, with 2 lone pairs, decreases the bond angle more (105)than one lone pair of ammonia (107). You do not need to know the exact bond angles of molecular geometries for the lone pair molecules but be aware of this and why.

PHET Simulation of VSEPR:

PHET Simulation of Polarity:

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3/7 – Monday Homework: –

1: Watch the sp³ lecture and follow along with me with the SP3 hybridization.pdf worksheet.

Use the octet hybridization family (images) posted above as needed.

sp3 hybridization.pdf
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sp3 hybridization key p.pdf

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2: Please complete the Hybridization Comparison Chart Intro.pdf with me. You may skip the first 2 side on the worksheet as we did them in class today. Start the video at 19:00 to the end to complete the back side.

IF we completed all three rows and the back then you can skip this video and worksheet.

Period 3 and 4 finished this in class.

You may need to review if you are having trouble or if it was not clear from watching from home today.

Use the octet hybridization family (Images) posted above as needed.

Hybridization Comparison Chart Intro.pdf

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3: Please complete the Ethane, Ethene, Ethyne Comparison.pdf with me with the video with me!.

Use the octet hybridization family posted above as needed.

Ethane, Ethene, Ethyne Comparison.pdf
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Ethane, Ethene, Ethyne Comparison worksheet key p.pdf
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Lecture on the Ethane, Ethene, Ethyne Comparison.pdf worksheet:

Also in the last few minutes of this lecture I review the bonding in Ibuprofen and Aspirin.

You do not have that worksheet yet.

4. Complete the Hybridization 3 form below: (you have 3 submissions.)

1. sp3 Lecture:

2. Video for Hybridization Comparison Chart Intro.pdf Homework::

3. Lecture on the Ethane, Ethene, Ethyne Comparison.pdf worksheet:

Also in the last few minutes of this lecture I review the bonding in Ibuprofen and Aspirin.

You do not have that worksheet yet but it may help you

4 : Hybridization Form 1 – 2021

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PHET Simulation of Polarity:

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3/8 – Tuesday – B Day – 2, 3b/4 Lab

Main focus –

a) To Compare and contrast ionic and molecular compounds in terms of electrical conductivity and types of formulas (empirical and molecular).

b) To identify a debyne as unit of polarity and that they molecular shapes of molecules periodically repeat.

c) To write a Lewis Dot Diagram for polyatomic ions

Period 2 3/4:

1. Homework review (last nights) – Hybridization 3 worksheet

Hybridization Form 3 – Key p.pdf
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2. Bonding presentation: slides 12 – 29:

a) conducting electricity demo ionic/molecular

i) Flash emulator for the ionic compounds – electrolytes

b) Molecular polarity demo – non – electrolytes

c) partial charges, dipole moments, overall dipole moment =

u = separation of charge x distance

Dipole Moment = debyes = coulomb – meter

3.33 x 10^-33C m = 1 debyes —> 1 D

need to show polar slide in bonding demo

Bond polarity/molecule polarity PHET

3. Complete the polarity discussion with

a) showing overall dipole moments for the molecules in the homework –

– WATER VS CARBON DIOXIDE – The meaning of Life!

b) Polyatomic ion – Table E in presentation Lewis structures (model a couple) from the backside of Hybridization Comparison Chart worksheet.

Hybridization Comparison Chart Intro.pdf

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c) Identify hybridization and lewis structures that are PERIODICALLY similar.

4. Bond Energy – Bond Energy and Bond length discussion with table below:

Carbon – Carbon bonds, electronegativity in HF, HCl, HBr, HI. Why is HI strongest acid?

TODAY’s NOTES:

Bond Energy and length data:

Bond energy = the energy needed to break bonds = Bonds are stable thus Bond energy is always positive.

Bond length = distance between nuclei of atoms in a bond.

Stronger the bond, stronger the attraction to the electrons between the bonded atoms and

this will lead to a shorter bond length.

Stronger the BOND Energy the shorter the BOND length!

π (pi) bonding occurs with every multiple bond between 2 atoms but it does not double or triple the bond

energy because π bonding contains electron density that IS NOT between 2 nuclei. I often describe π

bonding as bonds that are perpendicular to the 2 nuclei that are simultaneously attracting the electrons.

This is weaker than if the electrons are located exactly between the 2 nuclei in σ (sigma) bonding.

Bonding Presentation:

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3/8 – Tuesday Homework: –

Formal charges/ resonance –

We use formal charges to evaluate lewis structures so that we pick the most stable and realistic structure. THIS IS WHAT TONIGHT’s HOMEWORK is on!

In resonance the formal charges will be the same for all elements except that they will be in different locations. Formal charges will help verify the overall charge on polyatomic ions

1. Please view the lecture below on formal charges on the first side ONLY of the Formal Charges with Chlorate geometry 1718.pdf worksheet.

Formal Charges with Chlorate geometry 1718.pdf
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Formal Charges with Chlorate geometry 1718 key p.pdf
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Formal Charge Lecture:

2: Please complete the Hybridization identification worksheet 1617.pdf

and review with key below:

I made a mistake in the key. The carbon not highlighted in Ibuprofen should be sp³ .

Also NO₃^-1 has a molecular geometry that is trigonal planar!

Hybridization identification worksheet 1617.pdf
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Hybridization identification worksheet key p 1617.pdf
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3. Complete the form below:

4 : Hybridization Form 1 – 2021

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3/9 – Wednesday – A Day – 2/3a Lab, 4

Main focus –

a) To identify the best Lewis Dot structure through formal charges

b) To write lewis dot diagrams with resonance.

c) To determine the Bond Order of a molecule and how it is different in resonance.

Period 2/3, 4:

1. Review of Homework form: –

a) Formal Charges b) Bond Energy c) Bond Length d) dipole moments e) *Resonance

Hybridization Form 4 – Key p.pdf
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2. Review of Hybridization worksheet.

Hybridization identification worksheet key p 1617.pdf

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3. Resonance – delocalization of electrons through multiple bonding orbitals

– Complete NO₃^-1 polyatomic i0n lewis structure and discuss resonance and introduce Bond Order.

– Demonstrate Resonance through the un-hybridized p orbitals.

– Demonstrate how the formal charges stay constant

– Introduce Bond order and how it is different when there is Resonance

– How is Bond Energy and Bond order different with Resonance?

– How to identify it?

Practice with Formal charges and resonance:

Classwork:

Formal Charges & Resonance Follow Along.pdf
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4. Expanded octets – Started back side of Formal Charges with Chlorate geometry 1718.pdf in class.

add Bond orders, formal charge/ resonance 17 – 21 slides in Resonance Presentation

Formal Charges with Chlorate geometry.pdf
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TODAY’s NOTES:

*Formal Charges will help us determine how many double bonded oxygen in more advanced structures (chlorate structures). we keep adding the double bonds till the central atom will become a formal charge of zero. Remember that Formal Charges are “bookkeeping values” that help us determine the most accurate Lewis Structure. They are part of this valence bond theory that is not perfect in explaining or predicting the properties of all molecules but without experimental data you MUST follow formal charge rules:

a: Best Lewis Structure will have the more atoms at or near zero (atoms are using their valence electrons in the drawn Lewis structures).

b. If given a choice the most Electronegative Atom will have a negative value (that atom will gain the electron because of its larger coulombic attractions for electrons).

c. If the formal charges stay constant for different Lewis Structures for the same molecule or ion then you have Resonance.

Bond Order = All the bonds in a molecule (pair of electrons between atoms)

All the regions in the Lewis Dot Diagram that have bonds.

Molecules with resonant structures have Bond orders that are decimals to show that the electrons are are delocalized throughout the entire molecule!! This adds a little extra bond energy in every domain AND THUS THE BOND LENGTHS and BOND Energy will be somewhere in between a single and double bond!

Bonding Presentation: slide 35 – 47 today

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3/9 – Wednesday Homework: –

1. Make sure you have reviewed last nights form with the key

Hybridization Form 4 – Key p.pdf
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2. Watch the Hybridization lecture – sp³d, sp³d² lecture below (Expanded Octets Lecture):

We know that elements in Row 2 can only have a max of 8 electrons shared (octet rule!).

So it makes sense if we have elements with a n number greater than 2 (beyond row 2) then we can have Lewis dot structures that have more than 8 for our central hybridized atoms.

3: Then complete the Hybridization identification worksheet 2 expanded octets.pdf and start this worksheet with another video that models the first few chemicals and then review with the key.

Use my lecture and the worksheets to figure out the new geometries of the 2 NEW hybrid families!

Expanded octet geometry comparison chart.pdf
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Bonding Tables – molecular geometry and Hybridization p.pdf

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Hybridization identification worksheet 2 expanded octets.pdf
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Hybridization identification worksheet 2 expanded octets.pdf KEY.pdf
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Expanded Octets Lecture:

Lecture that models a few of the chemicals in the

Hybridization identification worksheet 2 expanded octets.pdf worksheet:

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3/10 – Thursday – B Day – 2, 3b/4 Lab

Main focus –

a) To write a lewis dot diagram with resonance for a molecule and a polyatomic ion.

b) To utilize formal charges in guiding the Lewis dot structures in complex structures

c) To Identify the geometry of molecules and ions that have sp3d and sp3d2 hybridization.

Period 2: –

1: Complete the backside of the Formal Charges & Resonance Follow Along.pdf worksheet. specifically we will complete the Lewis dot diagrams for NO2- and O3. I will add SO2, SO2-2, and SO3.

– discuss benzene’s stability with its delocalized electrons in its resonance structure

2. Expanded Octets –

VSEPR (Valence Shell Electron Pair Repulsion ) Balloons – Grodski Balloon expanded octets hybridization

demo and lewis diagram demo. Balloons and PHET simulation used.

– Review of all electron domain geometries and molecular geometries of expanded octets and modeled a few of the lewis structures.

Hybridization identification worksheet 2 expanded octets.pdf

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Hybridization identification worksheet 2 expanded octets.pdf KEY.pdf
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Period 3/4: –

Same as above except

TODAY’s NOTES:

Benzene, C₆H₆ that has resonance : What is the hybridization of Benzene?

Anyone remember the Aspirin Lab? (do you see a benzene ring in the structure)?

PHET Simulation of VSEPR:

Resonance, Formal Charges & Polyatomic Ions: for Dipole Moments

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3/10 – Thursday Homework: –

1. Please complete the take-home quiz. I have linked a google doc to your private email. Please complete the quiz on the given paper I handed out in class AND THEN take a picture of it and insert in into the shared google doc as proof that you have completed the quiz on time. I will grade from the google doc. IT WILL CLOSE AT 9:00 PM.

Molecular model quiz – Mock 1718.pdf
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AFTER 9:00 PM, I WILL POST THE KEY AND A REVIEW VIDEO HERE:

2. PLEASE Review YOUR QUIZ.

Molecular model quiz – Mock 1718 key.pdf
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Tomorrow you will take another in class. Tomorrows quiz in class has a weight with of 5 forms.

VSEPR Balloon Lesson did today :

Formal Charge and Resonance Extra Resource :

How to sketch the hybridized molecular structure – Extra Resource :

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3/11 – Friday – A Day – 2/3a Lab, 4

Main focus –

a) To interpret a potential Energy Internuclear Diagram in terms of bond energy and bond lengths.

b) To identify the factors that contribute to the strength of Lattice constants.

Period 2/3 /4–

1. Review of sp³d and sp³d² expanded octets through quiz examples:

2. Take the Molecular Model Quiz 2 (weight of 5) : Timed 15 minutes.

3. Potential Energy Internuclear distance Diagram

Complete the Potential Energy Internuclear distance Diagram

Use diagram to explain Bond Energy and Bond Length with chart posted this week.

Potential Energy Internuclear distance Diagram.pdf

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Run through slides 36 – 39:

4: Lattice Energy – Lets Remember that we have ionic compounds that are in the mix. They are ions attracting themselves in a crystal lattice and are not part of the hybridization or polarity discussion. Because all ionic compounds are solids (in crystal arrangements) at STP we use lattice energy to describe their stability or strength of ionic character. Much like we use the difference of electronegativity for the dipole moment of each polar bond in covalent (molecular) compounds.

5. Limitations of valence bond theories.

Lattice Energy presentation:

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TODAY’s NOTES:

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!!!

OK so what if we run into a Lewis Diagram that is beyond the Valence Bond Theory?

The Current AP Curriculum does not support using Formal Charges to provide guidance in building lewis dot diagrams that are beyond the Octet Rule. The rest of the world does so we make the following rule when dealing with AP:

If there is a element that exists in row three and beyond then the octet rule takes preference:

Does experimental evidence support this rule completely? No. Does experimental evidence support the use of formal charges completely? No. We need a new theory!

Example: SO_4-² , SO₃

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!

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3/11- Weekend Homework: –

1. Please review your Periodicity test that I handed back with the key that will be in Powerschool by Friday afternoon. If you think you got something right and I marked it wrong please ask me Monday.

2. Please complete the Bonding Test 1 – Take Home. Take as much time as you need to complete BUT you will have a timed Test on Monday (30 minutes) on Bonding Test 1 – (weighted twice as the take-home). I will review this with you with the key before we take the timed test.

3. Please view the MO theory MIT Lecture and complete the form below. (Please hold unto the worksheets I gave out Friday). MO Theory is non-valance bond theory that picks up where Lewis Dot Diagrams and Hybridization eventually fail. Please read my Notes above on the limitations of the valence bond theory before you begin the MIT LECTURE and Form.

*BONDING Test Topics –

Lewis Diagrams (molecules and polyatomic ions), determining Hybridization (sp, sp² , sp³⁾ electron domain geometry, molecular geometry, bond angles, polarity, drawing orbital sketches

Sigma, pi bonds,

Bond order (total bonds / places that can have bonds).

Formal Charges to determine the best lewis diagram, lattice energy

There will be NO sp3d or sp3d2 on the 1st bonding test.

THERE WILL BE NO (on the Take-home)

a) Expanded octets with sp3d,and sp3d2 hybridization

b) A POLYATOMIC ion like the chlorate geometry worksheet –

c) Dipole moments – Slide 22 – 34 –

d) Potential Energy Internuclear distance Diagram –

But these extra topics will be included on Monday’s test.

Mondays’s test will have the same material PLUS

a) Expanded octets with sp3d,and sp3d2 hybridization

b) A POLYATOMIC ion like the chlorate geometry worksheet –

c) Dipole moments – Slide 22 – 34 –

d) Potential Energy Internuclear distance Diagram –

3 :MIT MO Theory Lecture:

3 : MO Theory Form

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MO theory to Band THeory: For Next week.

Polar and Nonpolar molecules with Static Electricity Demo

Animation of Water in above demo: