Outline for Today Friday, Dec. 7 Festivities A Non-Exhaustive - - PowerPoint PPT Presentation

Outline for Today

Friday, Dec. 7

• Festivities
• A Non-Exhaustive Overview of CH 141
• Selected Integrative (and Challenging) Example

Problems

2

Final Exam Review Opportunities

• Review Session: 4pm - 6pm Sunday Dec. 16th, Keyes 105
• Prof. Madison’s Office Hours: 1pm - 2pm Monday through

Friday

• Monday and Tuesday, Keyes 104 (Chem Help Center)
• Wednesday through Friday, my office Keyes 314
• By Appointment: Expect an email today! One

appointment per person. First come, first served.

Note Card Warm-Up Exercise

• 1) Name
• 2) Why do we use salt to melt ice?
• 3) Why do we add salt to pasta water?
• 4) Why does warm soda go flat?

The Big Questions in General Chemistry

• What is our material world is made of?
• How and why do atoms stick together to

form molecules?

• Why do molecules and materials have the

properties that we observe?

• How do molecules chemically react?

What is our Material World Made of?

Chemicals!

• You should now be able to:
• For any molecule that we’ve talked about in class, you

should now be able to:

• Draw the best possible lewis structure.
• Predict 3D shapes of molecules.
• Describe a molecule’s properties based on its structure.

Ch 2, 9, 11, 13 Ch 9 Ch 9 Ch 8

What is our Material World Made of?

• Relate certain names to chemical and/or empirical

formulas.

• Describe the structure of atoms or ions based on

subatomic particles (protons, neutrons, and electrons).

• Describe the electronic structure of atoms, ions, and

molecules using quantum numbers, molecular orbitals, electron configurations, etc.

Ch 2 Ch 6 Ch 2

Remember, this list is just a starting places. It is not exhaustive!

Example Problem: Drawing Lewis Structures

• Draw the lewis structure and predict the 3D shape for

phosphorous-dichloro-diflouride. What are the angles?

Cl Cl F F

Ch 8 and 9

Example Problem: Behavior

• f Electrons

What orbital is this? What are the quantum numbers for this orbital? Which regions of this orbital are most responsible for shielding?

Ch 6 and 7

Example Problem: Atoms, ions and their subatomic particles

• Sort the following by increasing radius:
• 1. Ca, K, S, and Cl
• 2. K+, Ca2+, S2-, and Cl-
• Using the subatomic particles, explain why.

Ch 7 and 2

Why do Molecules and Materials Have the Properties that They Do?

• You should now be able to:
• Distinguish physical properties from chemical properties.
• Relate molecular shapes and polarity to chemical

properties.

• Numerically analyze the behaviors of gases, liquids,

solids, and solutions.

Ch 1 Ch 11 Ch 10, 11, 12

Why do Molecules and Materials Have the Properties that They Do?

• You should now be able to:
• Relate electronic structure of diatomic molecules to

molecular properties.

• Relate electronic structure to periodic trends.

Ch 9 Ch 7

Remember, this list is just a starting places. It is not exhaustive!

Example with Molecular Structure of DNA

• The DNA base pairs are

Thymine and Adenine, Cytosine and Guanine.

• Which pair of DNA

bases is more stable to heating? AT or CG?

• Why?

Ch 8 and 13

Example: Photons and Electrons in modern materials (Nanoparticles)

smaller nanoparticles larger nanoparticles

Ag

Many more electrons below here! Highest Occupied Molecular Orbital Lowest Unoccupied HOMO

Photon absorption!

1 x 1

• 9

m

If a solution absorbs green light, then it appears red to us.

Question: Based on the color of the solution, which nanoparticles, (smaller or larger), absorb photons with the most energy?

smaller nanoparticles larger nanoparticles

E = hc λ

hint:

looks red absorbs green

λ = λ =

How do Chemicals React?

• You should now be able to:
• Balance chemical reactions
• Write chemical reactions between different molecules

based on the type of reaction (acid-base, precipitation, combustion, etc.)

• Using the concept of limiting reagent, determine what is

produced from a reaction.

Ch 3, 4, 20 Ch 3, 4, 20 Ch 3, 4, 10

How do Chemicals React?

• You should now be able to:
• Quantitatively account for energy flow (absorbed or

emitted) in a reaction in terms of heat, work, or light.

• Relate the enthalpy of a reaction to thermodynamic

processes like heating, cooling, and phase changes.

• Relate enthalpy changes to changes in chemical bonding

because of a reaction.

Ch 5, 6, 11 Ch 5, 11 Ch 5, 8

Remember, this list is just a starting places. It is not exhaustive!

Example of Redox Reactions and Enthalpy of Reaction

• When 500.0 mL of 0.50 M Cr2O72- is mixed with 9.0 g of Al(s)

and excess H+(aq), it forms Al3+(aq) and Cr3+ (aq) through a redox reaction.

• After the reaction takes place, what is the concentration of

Al3+(aq)?

• Does the solution boil? Assume the solution starts at 4oC.

Important data for this problem:

• Cp (solution)=4.1 J/g oC
• Kb=1.86 oC / m
• Density of solution at 4oC= 1.00 g/mL
• ∆Hrxn= -1500. kJ/mol Cr2O72-

Important topics

• Redox Reactions
• Limiting Reagents
• ∆Hrxn
• Heat capacity
• Boiling point elevation