3 January 2012 Take Out Bonding Problem Set Objective: You will be able to:

describe the VSEPR model and describe molecular geometry for 2 to 4 electron domains

Do now: On your white paper, across the top of a long edge, draw the Lewis structures for:

1. carbon dioxide2. boron trifluoride3. methane4. ammonia

Agenda

I. Homework QuizII. Collect Winter Break Homework

We’ll do a review of intermolecular forces after this current (short) unit

III. VSEPR Theory and Molecular GeometryHomework: p. 453 #1, 2, 7, 9, 12 (please

sketch neatly!): tomorrowI’ll collect the Intermolecular Forces

problem set tomorrow. See me after school with questions!

Keys?

The VSEPR Model

Valence-shell electron-pair repulsion (VSEPR) model: a way to use Lewis structures to determine the geometries (shapes) of molecules. based on repulsive forces that exist

between electron pairs within molecules geometry: the arrangement of a

molecule’s atoms in three-dimensional space

bond angle: an angle made by the lines joining the nuclei of atoms in a molecule

electron domain: a region around an atom in which electrons will most likely be found. produced by a non-bonding pair, a

single bond, a double bond or a triple bond

Activity

1. On your white paper, across the top of a long edge, draw the Lewis structures for:

1. carbon dioxide2. boron trifluoride3. methane4. ammonia

2. Then, with your knowledge of the VSEPR theory, construct models for each molecule that predict it’s 3D geometry. Sketch these below each Lewis structure.

3. Measure and label the bond angles.

Linear2 bonding domains0 non-bonding domains

180o

Trigonal Planar3 bonding domains0 non-bonding domains120o

Non-linear (bent)2 bonding domains1 non-bonding domain117o

Tetrahedral4 bonding domains0 non-bonding domains109.5o

Trigonal pyramidal3 bonding domains1 non-bonding domain107o

Non-linear (bent)2 bonding domains2 non-bonding domains104o

On your paper

Label the shapes of the four molecules you already constructed

Draw Lewis structures for NO2

-

H2O Determine their shape. Build the

model. Draw a sketch, label the shape name

and the bond angle.

Next Up

What about molecules with 5 or 6 electron domains?!

Homework

p. 453 #1, 2, 7, 9, 12: tomorrow

4 January 2012

Take Out: Problem sets, p. 453 Homework Objective: You will be able to:

use VSEPR theory to determine the shapes of molecules with five and six electron domains around the central atom.

Homework Quiz: Draw the Lewis structure, determine the shape, sketch, label the bond angle: HCF3

Bonus: Describe the polarity of this molecule.

Agenda

I. Homework QuizII. Homework AnswersIII. Shapes of molecules with five and

six electron domains: NotesIV. Polarity? Homework: p. 453 #7d, 8, 10, 12d,

e, g, 13, 14: Mon. read p. 420-423, ignore equations:

Mon.

Draw Lewis Structures for…

PCl5

SF4

ClF3

XeF2

Electron-Domain Geometry

Trigonal bipyramidal: 5 electron domains trigonal bipyramidal (5 bonding, 0

non) seesaw (4, 1) T-shaped (3, 2) Linear (2, 3)

Draw Lewis Structures for…

SF6

BrF5

XeF4

Electron-Domain Geometry

Octahedral: 6 electron domains octahedral (6 bonding, 0 non) square pyramidal (5, 1) square planar (4, 2)

9 January 2012

Take Out Homework Objective: You will be able to:

identify and describe the polarity of bonds and molecules

Homework Quiz: a. Draw a Lewis Structure b. Identify the shape c. Sketch a. IBr3 b. SI6

Agenda

I. Homework QuizII. Homework AnswersIII. Polarity Notes and Practice

ProblemsIV. Hand back assignmentsHomework: p. 454 #18, 20, 23finish polarity practice problemsread p. 428-436

Practice Problems

Draw Lewis Structures, predict geometry (electron domain and molecular), sketch, label: PBr5

SI6

ClF4+

SF5-

BCl3

IBr3

XeCl2

Polarity

bond polarity: a measure of how equally the electrons in a bond are shared between two atoms. the greater the difference in

electronegativity of the bonded atoms, the more polar the bond.

dipole moment: measure of the charge separation in a molecule; how polar the entire molecule is the vector sum of all the bond

dipoles

Examples

HCl BF3

CCl4

NH3

CH3Cl

Examples

C2H2Cl2

Practice Problems

1. SO2 9. BF3

2. CCl4 10. SF3+

3. CHCl3 11. XeF2

4. TeCl2 12. BrF5

5. CO32- 13. XeF4

6. NH3 14. SeF4

7. SO42- 15. ClF3

8. CO2 16. SeF6

Homework

p. 454 #18, 20, 23 finish polarity practice problems read p. 428-436

10 January 2012

Take Out Homework Objective: You will be able to:

describe and identify hybridization of orbitals in molecules and describe and count sigma and pi bonds.

Homework Quiz: SF3+ a. Draw the

shape and label with the shape name. b. Indicate bond moments. c. Indicate dipole moment, if any. d. Polar or non polar?

Agenda

1. Homework Quiz2. Hybridization Notes and Practice

Problems3. Sigma and Pi Bond Notes and

Practice ProblemsHomework: p. 454 #31, 32, 34, 35,

37, 39, 40, 41, 42, 69, 71, 75, 82, 99 b0nus: 100: Thurs.

Hybridization

VSEPR Theory Review

Valence electrons only are involved in bonding.

Non-bonding and bonding electron pairs around the central atom repel each other.

This repulsion causes specific shapes and bond angles for each molecule.

Question

How can atoms, that have s, p and d orbitals, bond in ways that make the molecule shapes?

Ex: p orbitals at 90o angles to each other. How can they make a bond angle of

109.5o in tetrahedral or 120o in trigonal planar?? ?

37

1s 2s 2p 1s Carbon Hydrogen

How can carbon make four bonds with four hydrogen atoms?? How can those bonds be at 109.5o (tetrahedral)?

Energy

Answer: Hybrid orbitals: the sublevels in an atom’s outer shell recombine into new orbitals of equal energy with different shapes and angles.

1s sp3 hybrid orbital

Energy

• Hybridization: the mixing of atomic orbitals in an atom (usually the central atom) to generate a set of hybrid orbitals.

Total energy the same, but redistributed

39

1s 2s 2p 1s Carbon Hydrogen

Energy

1s sp3 hybrid orbital

Energy

Animation

http://www.youtube.com/watch?v=g1fGXDRxS6k

http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/hybrv18.swf

sp3 Example

CH4

sp hybridization

BeCl2

12 January 2012

Objective: You will be able to: describe and identify hybridization

of orbitals in molecules and describe and count sigma and pi bonds.

review bonding and molecular geometry.

Agenda

Hybridization notes Practice problems Sigma and pi bond notes and examples Problem Set work timeHomework: p. 454 #31, 32, 34, 35, 37,

39, 40, 41, 42, 69, 71, 75, 82, 99 b0nus: 100: Tues.

Problem Set: TuesTest Weds.

sp2 hybridization

BF3

Shapes of hybrid orbitals

s, p

s, p, p

s, p, p, ptrigonal pyramidal

NH3 is also sp3 hybridization: three orbitals for the H, one orbital for the non-bonding pair.

Steps to Determine Hybridization

1. Draw the Lewis structure2. Predict the molecule shape using

the VSEPR theory3. Determine hybridization by

matching the arrangement of the molecule with known examples (table 10.4)

For each compound’s central atom, draw the orbital notation.

Then, draw the orbital notation after hybridization.

Name the type of hybridization and the shape of each molecule.

1. BeH2

2. AlI3

3. PF3

4. SiF4

5. CO2

6. PH3

7. H2O

Multiple Bonds

When a double bond forms, the two bonds are not exactly the same. First: “end on” s-orbital

interaction: σ (sigma) bonds Second: “side on” p-orbital

interaction: π (pi) bonds

Single bonds: always σ bonds. Double bonds: one σ + one π

bond. Triple bonds: one σ bond +two π

bonds

Count sigma and pi bonds CHCl3 SCO SeO2

ClO3-

Practice Problems Count the total number of sigma and

pi bonds in each molecule Draw a Lewis structure first!

1. H2CO2. O2

3. CO2

4. HCN (C is the central atom)5. CSN- (C is the central atom)6. N3

-

Homework

p. 454 #31, 32, 34, 35, 37, 39, 40, 41, 42, 69, 71, 74, 75, 82, 99 b0nus: 100: Thurs.

17 January 2012

Objective: You will be able to: review chemical bonding and molecular

geometry for a test. Homework Quiz: For the molecule on

the board:a. Describe/label bond moments and dipole

moment, if any.b. Describe the hybridization around each

C atomc. How many sigma bonds? Pi?

Agenda

I. Homework quizII. Questions on problem

set/homework?III. Collect problem setIV. Midterm ReviewHomework: Unit 6 test tomorrow

Unit 6 Test

12 multiple choice 1 four-part free response 1 period!!

Midterm Exam

I. 26 multiple choice, no calc.II. 2 predict products/write equationIII. 2 multi-part free response, with

calc. 110 minutes

Textbook Homework

Questions?

Problem Set

Questions?

Homework

Study for Unit Test Midterm Review starts Thursday