Archive for November, 2018

Making White Light – materials research for a better world

Incandescent bulbs are one of the most energy-inefficient products in daily use,” Joanna McKittrick says. Touch a regular old 100-W light bulb after it’s been lit for a few minutes, and you’ll see what she means.

Less than 5% of the electrical energy that goes into the tungsten filament inside is converted to visible light, explains McKittrick, a luminescent materials specialist at the University of California, San Diego. The rest is wasted as heat that, should you follow our instructions, will burn your fingers.

Incandescents “basically haven’t changed since Thomas Edison invented them” about 140 years ago, she says.

Discovered via computational screening for new phosphors, this compound (above) is the first member of the previously unknown Sr-Li-Al-O crystal family. Black outline = unit cell. Gold = Sr. Red = Li. Green = Al. Blue = O.

Bulbs that contain light-emitting diodes (LEDs), on the other hand, can produce the same amount of white light but barely feel warm to the touch. That’s because LEDs are more energy efficient. A 15-to-20-W LED can produce the same brightness as a 100-W incandescent, roughly 1,500 lumens. LEDs are also less fragile and can last tens of thousands of hours longer. Nevertheless, these modern alternatives currently account for less than 10% of lighting worldwide, according to data from the U.S. Department of Energy.

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Week 13 Schedule: Section B

This week we will build off of the concepts of molecular structure, polarity,  and dipole moments to understand how intermolecular forces stick molecules to each other in the liquid and solid phases.  We will explain properties of liquids and solids as well as their phase changes from the intermolecular forces that occur between molecules.

Reminder: Exam #3 is on Wednesday.  More information can be found here.  There is a review session on Monday at 7pm.

Homework #12 will be due next week on Wed. December 5th.

Monday Lecture Materials: Lecture slides 11-26Class notes 11-26

Wednesday Lecture Materials: Lecture slides 11-28Lecture slides 11-28-With soln to PracticeClass notes 11-28

Viscosity and the Pitch Drop Experiment

Friday Lecture Materials: Lecture Slides 11-30

Surface Tension in Space:

Week 13 Mon 11/26 Tue 11/27 Wed 11/28 Thu 11/29 Fri 11/30
In Class Chapter 11 Chapter 11 Chapter 11
Learning Objectives Molecular Comparison of solids, liquids and gases. Relating molecular structure to intermolecular forces. Relating properties of liquids to their intermolecular forces. Structures and bonding of solids.
Topic Liquids and Intermolecular Forces Liquids and Intermolecular Forces Liquids and Intermolecular Forces
Outside of Class
Homework Work on Homework #12
Reading 1st read of chapter 11 2nd read of chapter 11
Other Things to Remember Review Session 5pm-7pm Keyes 105 3rd Exam is Tonight from 5-7pm in Keyes 105 Office hours 1:00-2:30pm
Practice Problems 11.12, 11.15, 11.17, 11.21, 11.22 11.29, 11.32, 11.37, 11.39, 11.45 11.51, 11.55, 11.59, 11.61, 11.71

Solids and Liquids – Making the Oceanographer Happy

Reading chapters 11 and 13

Intermolecular Forces:
London, dipole-dipole, hydrogen bonding, ion-dipole
Comparison of forces
Properties of  Solids, Liquids, and Gases
Phase changes
Heating curves

Resources:   hydrogen boding in biological structures,  Chapter 11 Images 2018, Chapter 11 Notes, Chapter 13 Slides 2018, Chapter 13 notes




Third Exam and Review Session

Reminder: Exam 3 is Wednesday, Nov. 28.  Exam Locations: Keyes 105, 102, 103, and 114.

Practice exams and their solutions can be found on the Sample Exam page.  The relevant files are Practice Exam 3, Exam 3 (with answers) from 2016, and Practice Exam 3 2017.  You are strongly encouraged to do these practice exams before Monday 11/26.  

Exam information: Exam 3 will be held on Wed, Nov. 28 from 5:00-7:00 pm. You may work for the entire 2 hours, but the exam is expected to take most students 60 min. The exam will cover the class material from chapters 1-10 and laboratory material from up to and including experiment 9.  Chapters 6-9 will be emphasized (Electronic Structure of Atoms through Molecular Geometries and Bonding Theories).   Allowed exam items are pens/pencils and a course-approved calculator. You will be provided with a periodic table and equation sheet.

There will be an optional review session on Monday, 11/26 in Keyes 105 at 7 PM.

Equation Sheet Exam 3

“Week” 12: Section B

On Monday we will look at more challenging and integrative practice problems from chapter 9.  These practice problems will help you prepare for exam #3 which will take place on Wednesday, Nov 28th at 5pm.

Be sure to look at the practice exams posted under “Sample Exams and Exam Solutions” over the next week.  I also recommend that you do the practice problems posted on this blog as well as those posted on Mastering Chemistry.

I hope you have a fantastic and restful Thanksgiving!

Monday Lecture Material: Lecture Slides 11-19Class notes and solutions to Integrative Examples 11-19

Week 12 Sat 11/17 Mon 11/19 Tue 11/20 Wed 11/21 Thu 11/22 Fri 11/23
In Class Chapter 9 No Class No Class
Learning Objectives Compare and contrast the 4 bonding theories. Apply the 4 bonding theories to challenging molecules.
Topic Bonding Theories
Outside of Class
Homework Work on HW #11 Work on HW #11 Finish HW #11 Homework #11 is due at 11:59pm
Reading Read chapter 9 First read of Chapter 11
Tasks Eat & Relax Attempt Practice Exam #3
Practice Problems 9.85, 9.89, 9.91, 9.97, 9.99

Play with this! Geometry Builder


Week 11: Section B

This week we will continue our discussion of molecular bonding.  We will learn how to turn our two dimensional Lewis structures into to three dimensional molecular geometries.  By the end of the week we will be able to apply and analyze four theories of molecular bonding: Valence Shell Electron Pair Repulsion theory, Valence Bond theory, Hybrid Orbitals, and Molecular Orbital Theory.

Homework #10 is posted on Mastering Chemistry and it covers chapter 8. It is due on Wednesday at midnight.

Monday Lecture Material:Lecture Slides 11-12class notes 11-12

Wednesday Lecture Material: Lecture Slides 11-14class notes 11-14

Friday Lecture Material:Lecture Slides 11-16class notes 11-16

Week 11 Sat, Sun 11/10-11 Mon 11/12 Tue 11/13 Wed 11/14 Thu 11/15 Fri 11/16
In Class Chapter 9 Chapter 9 Chapter 9
Learning Objectives Describe the 3D structure of molecules based on VSEPR theory. Relate the hybrid orbitals used in bonding and to the 3D structure of molecules. Explain how molecular orbital theory is used to describe bonding in diatomic molecules
Topic Bonding Theories: VESPR Bonding Theories: Valence Bond Theory and Hybrid Orbitals Bonding Theories: Molecular Orbital Theory
Activities Balloon Models Building Molecular Models Will liquid O2 stick to a magnetic?
Outside of Class
Homework Work on HW #10 Work on HW #10 Work on HW #10 Homework #10 is due at 11:59pm Start HW #11 Work on HW#11 (Due Tues. 11/20 at Midnight)
Reading 1st Read of Chapter 9 2nd Read of Chapter 9
Other Things to Remember Special Office Hours Sun. 1pm-3pm Office Hours 2:30-4:00 Office Hours 1-2:30
Practice Problems 9.13, 9.17, 9.21, 9.27, 9.37 9.45, 9.49, 9.53. 9.55, 9.61, 9.63 9.59, 9.61, 9.69, 9.71

For your entertainment, a remake of “Shape of You” but with a mash-up of all the 4 bonding theories that we’ll discuss this week.

Week XI – Advanced Bonding – King

Reading:  Chapter 9

Homework:  Please see Mastering Chemistry

 Lecture Outline:

Molecular Shapes and VSEPR
Bond Strength and Energies
Valence Bond Theory
Molecular Orbitals  – Wave Example ISimple Wave II

Resources:  Chapter 9 Slides, Chapter 9 Notes 2018Chemical Education Molecule Viewer

Why we care about the shapes of Molecules –

Week 10: Section B

Molecular Bonding! This week we will build on what we’ve learned about valence electrons in chapters 6 and 7 in order to understand how atoms connect to form molecules.  We will start with ionic bonding  which builds directly out of concepts of ionization and electron affinity from chapter 7.  Then we will master drawing Lewis structures, including learning to draw resonance structures and learning when it is ok to break the octet rule.  By the end of the week we will be able to relate Lewis structures to bond strengths and to enthalpies of reactions.

Homework #9 covers chapter 7. It is due on Mastering Chemistry at midnight on Wednesday.

Monday Lecture Materials: Lecture Slides 11-5class notes 11-5

Wednesday Lecture Materials: Lecture Slides 11-7class notes 11-7

Friday Lecture Materials: Lecture Slides 11-9class notes 11-9

Week 10 Sat 11/3 Sun 11/4 Mon 11/5 Tue 11/6 Wed 11/7 Thu 11/8 Fri 11/9
In Class Chapter 7 and 8 Chapter 8 Chapter 8
Learning Objectives Relate electron configurations to periodic trends and observed exceptions to the trends. Write lewis structure for molecules. Use electronegativity to categorize bonding types. Use formal charges to identify the best lewis structure. Identify when resonance structures or exceptions to the octet rule are necessary to define bonding.
Topic Electron Affinity, Exceptions to Periodic Trends, Ionic Bonding Covalent Bonding, Bond Polarity, Lewis Structures Lewis Structure, Resonance Structures, Exceptions, Bond Enthalpy
Outside of Class
Homework Homework #8 is due at 11:59pm Work on homework #9 Homework #9 is due at 11:59pm Work on Homework #10
Reading 1st read of chapter 8 2nd read of chapter 8
Other Things to Remember Office Hours 2:30-4:00 Office Hours 1-2:30
Practice Problems 8.7, 8.9, 8.17, 8.19, 8.20 8.33, 8.35, 8.41, 8.45, 8.49 8.55, 8.56, 8.63, 8.65, 8.69, 8.71

Week X – Bonding – King

Reading:  Chapter 8

Homework:  Please see Mastering Chemistry

 Lecture Outline:

Ionic Bonding
Lattice Energies
Covalent Bonding
Lewis Structures
Bond Polarity and Electronegativity

Resources:  Chapter 8 notes 2018,  Chapter 8 slides

Viewing Molecules:   Simple – ethanol, Complex – carbonic anhydrase