Chemistry WarmUp Copy ALL of these assignments into your binderIncluding dates, WarmUps, InClass assignments AND page numbers!August 30-31 WarmUp: Agenda and complete egg in a bottle lab reportInClass: Safety Contract review InClass: Lab Bubbles p23Homework: Read and take notes 1.3 p25 q18-25 DUE NEXT CLASS

Setpember 1 WarmUp: Hypothesis/Procedure/ObservationsInClass: Introduction to Dimensional AnalysisHomework: Read 1.4 answer q26-27p30 DUE NEXT CLASS

September 2-3WarmUp: Scientific Method and the Bubbles Lab RevisitedInClass: An Experimental Approach to Science p21TEInClass: Self-assess bubbles lab Quiz: Scientific Method ch1.1-1.3Lab: Using the metric systemHomework: Read 2.1 answer q3-7 DUE NEXT CLASSAs soon as you finish copying these assignments:Carefully read over and complete your Egg in a Bottle lab report.Compare your use the rubric to assign yourself a grade.

AnnouncementsSLAC: LEADING THE CHARGE: Exotic New Materials for Future Devices

September 28th 7:30-8:30For extra credit (10 homework or inclass points) turn in•Program•Your notes signed by the presenter or organizer.

http://www2.slac.stanford.edu/lectures/

EYH: October 9, 2010 UCSC

http://eyh.ucsc.edu/

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Chapter 1

Introduction to Chemistry

Chapter 1

Introduction to Chemistry

What is Chemistry?

• Study of matter composition, properties, & changes

• Applied chemistry attain goals

• Pure chemistry gather knowledge for knowledge’s sake

Why study Chemistry• Explain the natural world

– Why?

• Prepare for a career– Directly- in a lab– Indirectly- problem solving and thinking skills

• Be an informed citizen– Vote– Don’t get scammed

1.3 Alchemy

• Forerunner of chemistry

• Mystical- search for perfection

• Practical- developed glassware and techniques used today

• Tried to change elements

• Faulty assumptions and lack of logic led them astray

Scientific Method

• A way of solving problems or answering questions.

• Starts with observation- noting and recording facts

• Hypothesis- possible explanation of a set of observation– based on research – and previous knowledge

Scientific Method

• Experiment- designed to test the hypothesis

• only two possible answers– hypothesis is right– hypothesis is wrong

• Generates data -observations from experiments.

• Modify hypothesis - repeat the cycle

Scientific Method

Scientific Method

Variables

• Controlled experiment- one thing is changed.

• Manipulated variable- What you change or control directly – Also called independent variable

• Responding variable – What changes as a result. No direct control– Also called dependent variable

13

Origin of LifeOrigin of Life

14

Aristotle (384 –322 BC)Aristotle (384 –322 BC)

• Proposed theory of Proposed theory of spontaneous generationspontaneous generation

• Also called Also called abiogenesisabiogenesis• Living things can arise from Living things can arise from

nonlivingnonliving matter matter• Idea lasted almost Idea lasted almost 2000 2000

yearsyears

15

16

Examples of Examples of Spontaneous Spontaneous GenerationGeneration

17

Example #1Example #1• Observation:Observation: Every year in the Every year in the

spring, the spring, the Nile River floodedNile River flooded areas of Egypt along the river, areas of Egypt along the river, leaving behind nutrient-rich mud leaving behind nutrient-rich mud that enabled the people to grow that enabled the people to grow that year’s crop of food. that year’s crop of food. However, along with the muddy However, along with the muddy soil, soil, large numbers of frogslarge numbers of frogs appeared that weren’t around in appeared that weren’t around in drier timesdrier times

18

Example #1Example #1Conclusion:Conclusion: It was perfectly It was perfectly obvious to people back then obvious to people back then that that muddy soil gave rise to muddy soil gave rise to the frogsthe frogs

19

Example #2Example #2• Observation:Observation: In many parts of In many parts of

Europe, medieval farmers stored Europe, medieval farmers stored grain in barnsgrain in barns with thatched with thatched roofs (like Shakespeare’s roofs (like Shakespeare’s house). As a roof aged, it was house). As a roof aged, it was not uncommon for it to start not uncommon for it to start leaking. This could lead to leaking. This could lead to spoiled or moldy grainspoiled or moldy grain, and of , and of course there were course there were lots of mice lots of mice aroundaround..

20

Example #2Example #2Conclusion: It was obvious It was obvious to them that the to them that the mice mice came from the moldy came from the moldy grain.grain.

21

Example #3Example #3• Observation:Observation: Since there were no Since there were no

refrigerators, the mandatory, refrigerators, the mandatory, daily trip to the butcher shop, daily trip to the butcher shop, especially in summer, especially in summer, meant meant battling the flies around the battling the flies around the carcassescarcasses. Typically, carcasses . Typically, carcasses were “hung by their heels,” and were “hung by their heels,” and customers selected which chunk customers selected which chunk the butcher would carve off for the butcher would carve off for them. them.

22

Example #3Example #3Conclusion: Obviously, the Obviously, the rotting meatrotting meat that had been that had been hanging in the sun all day was hanging in the sun all day was the the source of the fliessource of the flies. .

23

Abiogenesis RecipesAbiogenesis Recipes• Recipe for mice:Recipe for mice:

Place a Place a dirty shirtdirty shirt or some rags in an or some rags in an open pot or barrelopen pot or barrel containing a containing a few few grains of wheatgrains of wheat or some wheat or some wheat bran, and in bran, and in 21 days21 days, mice will , mice will appear. There will be adult males appear. There will be adult males and females present, and they will and females present, and they will be capable of mating and be capable of mating and reproducing more mice.reproducing more mice.

24

Disproving Disproving Spontaneous Spontaneous GenerationGeneration

25

Francesco RediFrancesco Redi

26

Step 1 - ObservationStep 1 - Observation• There were flies around There were flies around

meat carcasses at the meat carcasses at the Butcher shop.Butcher shop.

• Where do the flies come Where do the flies come from?from?

• Does rotting meat turn into Does rotting meat turn into or produce rotting flies?or produce rotting flies?

27

Step 2 - HypothesisStep 2 - Hypothesis

• Rotten meat does not Rotten meat does not turn into flies. turn into flies. Only flies Only flies can make more flies.can make more flies.

28

Redi’s (1626-1697) Experiments

What is the the manipulated variable?

29

Redi’s (1626-1697) Experiments

What is the the manipulated variable?

30

Redi’s (1626-1697) Experiments

What is the responding (dependent) variable?What is the responding (dependent) variable?1. 1. Unsealed Unsealed – maggots on meat– maggots on meat2. 2. SealedSealed – no maggots on meat – no maggots on meat3. 3. GauzeGauze – few maggots on gauze, none on – few maggots on gauze, none on

meatmeat

Name several controlled variables:

31

Disproving Disproving Spontaneous Spontaneous Generation of Generation of

MicrobesMicrobes

Observations

Hypothesis

Experiment

• Cycle repeats many times.• By you and by others• The hypothesis gets more

and more certain.• Becomes a theory• A thoroughly tested model

that explains why things behave a certain way.

• Theory can never be proven.

• The best explanation

• Useful because it predicts behavior

• Helps us form mental pictures of processes (models)

Observations

Hypothesis

Experiment

• Another outcome is that certain behavior is repeated many times

• Scientific Law is developed

• Description of how things behave

• Usually an equation

• Law - how

• Theory- why

Observations

Hypothesis

Experiment

Prediction

Experiment

Modify

Observations

Hypothesis

Experiment

Law

Theory(Model)

Communication• Use Journals– Do research

– Write article

• Describe procedures, methods, and findings

– Submit for peer review

• Sent back for editing– Publish

• Letters to editor respond.

Collaboration

• Working together

• Teams– Different skills – Different specialties

• Internet and Email

• Conferences

Chemistry Warm Up1. How does a hypothesis become a theory?2. Are theories ever wrong?3. If a scientist subscribes to a hypothesis, butperforms an experiment that disproves the hypothesiswhat should he or she do?4. Explain the role of collaboration and communication in the scientific

method.5. What is

a. manipulated variable?b. responding variable?c. controlled variable?

Grading for this warm up:I didn’t understand, so I put my name and the date on the paper, and wrote down the questions – 1 pointI wrote complete and correct answers to at least half of the questions – 2 more points (total of 3 points)I wrote complete and correct answers to all of the questions 2 more points (total of 5 points)

When you finish, read and take notes 1.4 and andswer 26 and 27 in that chapter.

Problem Solving

• Only way to get good is to practice• Two parts

– Developing Plan-

• Hard part• Higher level thinking

– Implementing Plan-

• Not so hard• Application level

Solving Numeric Problems

• Three steps-1. Analyze

• Known– Numbers– Measurements– Equations

• Unknown– What are you looking for?– What units?

Solving Numeric Problems

• Three steps-1. Analyze

• Plan– The heart of problem solving– Diagram– Look info

» Table» Graph» Equation

Solving Numeric Problems

• Three steps-1. Analyze

2. Calculate

• Easiest part

• Convert measurements

• Rearrange

• Appendix C

Solving Numeric Problems

• Three steps-1. Analyze2. Calculate3. Evaluate

• Reasonable?• Read the question, did you answer it?• Check your work• Estimate

Practice

• What is the length, in centimeters, of a 10.0-inch ruler, given that there are 2.54 centimeters per inch?

Practice

• A certain ball when dropped from any height, bounces one-half the original height. If the ball was dropped from a height of 60 in. and allowed to bounce freely, what is the total distance the ball has traveled when it hits the ground for the third time? Assume the ball bounces straight up and down.

Conceptual Problems

• Without numbers or math

• Two steps1. Analyze

• Identify known and unknown

• Plan2. Solve

Practice• You find a sealed box

with strings protruding from three holes, as shown in the diagram. When you tug string A, it becomes longer and string C becomes shorter. When you tug string B, it becomes longer, but strings A and C are not affected. Make a diagram showing the arrangement of the strings inside the box.