BELL RINGER What is a Bell Ringer? BELL RINGER What is a Bell Ringer? -a question that is answered in the beginning of every class - these NEED to be.

BELL RINGER

What is a Bell Ringer?

BELL RINGER

What is a Bell Ringer?-a question that is

answered in the beginning of every class- these NEED to be written in

your notebook EVERY day

BELL RINGER

9/6What is a Bell Ringer?

A bell ringer is a question that is answered at the beginning of every class. It must done every day at the beginning of class.

BELL RINGER

List one thing you learned in school

yesterday.

1.1.I am employed as a beer testerI am employed as a beer tester

2.2.I am a certified cytogeneticistI am a certified cytogeneticist

3.3.I have coached an NBA playerI have coached an NBA player

4.4.I live in a house with 3 I live in a house with 3

females!females!

1.1.I am employed as a beer testerI am employed as a beer tester

2.2.I am a certified cytogeneticistI am a certified cytogeneticist

3.3.I have coached an NBA playerI have coached an NBA player

4.4.I live in a house with 3 I live in a house with 3

females!females!

1.1.I am employed as a beer testerI am employed as a beer tester

2.2.I am a certified cytogeneticistI am a certified cytogeneticist

3.3.I have coached an NBA playerI have coached an NBA player

4.4.I live in a house with 3 I live in a house with 3

females!females!

1.1.I am employed as a beer testerI am employed as a beer tester

2.2.I am a certified cytogeneticistI am a certified cytogeneticist

3.3.I have coached an NBA playerI have coached an NBA player

4.4.I live in a house with 3 I live in a house with 3

females!females!

BELL RINGER

What is Chemistry?

• Why do materials behave as they do?– Overall properties and reactivity

• How can we take advantage of these properties to something useful?

–New materials or improve existing materials–Pharmaceuticals, fuels, foodstuffs…

Medicine: “I have high cholesterol, what should I do?”– Eat Cheerios– Consult your best friend.– Pray to the god Baa and sacrifice a goat.– Take cholesterol lowering medication.– Adjust your diet

Science is a tool.

MathEnglishHistoryScience

Making GakPROBLEM:

= your recipe (amounts of ingredients)

= order of mixing, and how it was mixed

Explain your resultsCONCLUSION:

EXPERIMENT:

HYPOTHESIS:

How do you make GAK, efficiently?

BELL RINGER

What is the scientific method?

Goals

The Last Lecture

Safety Lab

BELL RINGER

What are these?

1. Observe an event.2. Develop a model (or hypothesis) which

makes a prediction.3. Test the prediction.4. Observe the result.5. Make your conclusion6. Revise the hypothesis.7. Repeat as needed.8. A successful hypothesis becomes a

Scientific Theory.

model

test

Medical ScienceScientific Method

High Cholesterol

Observation

Hypothesis (prediction)

Test

Observe result

Revise hypothesis?

New test?

Scientific Theory

Patient has high cholesterol

Certain chemicals may dissolve cholesterol deposits.

Give 100 patients these chemicals, give 100 patients

placebo.Same number lower their

cholesterol as placebo patients.

Try different combo of chemicals.Re-run medical test. Observe results.Lipitor reduces cholesterol.

Everyday Science

Scientific Method Car Repair

Observation

Hypothesis (prediction)

Test

Observe result

Revise hypothesis?

New test?

Scientific Theory

Engine won’t turn over.Predict battery is dead.Replace battery.

Engine now turns over.Not needed.

Not needed.

Cars won’t work without a fully charged battery.

Everyday ScienceScientific Method Making Spaghetti Sauce

Observation Spaghetti sauce should be red.

Hypothesis (prediction)

Test

Observe result

Revise hypothesis?

New test?

Scientific Theory

Try a tomato sauce.

Heat pot of tomato sauce.Taste the sauce - bland.

Use tomato sauce and garlic!Add garlic, taste - not so bland.The Final Recipe.

Making GakPROBLEM:

= your recipe (amounts of ingredients)

= order of mixing, and how it was mixed

Explain your resultsCONCLUSION:

EXPERIMENT:

HYPOTHESIS:

How do you make GAK, efficiently?

List, in order, the steps of the scientific

method.

BELL RINGER

1 dollar

X

= 29 quarters

You have $7.25 in your pocket in quarters. How many quarters do you have?

7.25 dollars 4 quarters=

1

A rattlesnake is 2.44 m long. How long is the snake in cm?

a) a) 2440 cm2440 cm

b)b) 244 cm244 cm

c)c) 24.4 cm24.4 cm

Chemistry In ActionChemistry In Action

On 9/23/99, $125,000,000 Mars Climate Orbiter entered Mar’s atmosphere 100 km lower than planned and was destroyed by heat.

1 lb = 1 N

1 lb = 4.45 N

“This is going to be the cautionary tale that will be embedded into introduction to the metric system in elementary school, high school, and college science courses till the end of time.”

Perform the following conversions -

A. 1.76 kg = ____________ dg

B. 0.0036 mm = _________ m

C. 5.2 x 10-2L = _________ cL

BELL RINGER

Counting Significant FiguresCounting Significant Figures

RULE 1. All non-zero digits in a measured RULE 1. All non-zero digits in a measured number are significant. Only a zero could number are significant. Only a zero could indicate that rounding occurred.indicate that rounding occurred.

Number of Significant Figures

38.15 cm38.15 cm 445.6 ft5.6 ft 2265.6 lb65.6 lb ______122.55 m122.55 m ___

Zeros in FrontZeros in Front

RULE 2. Leading zeros in decimal numbers RULE 2. Leading zeros in decimal numbers

are are NOTNOT significant. significant.

Number of Significant Figures

0.008 mm0.008 mm 11

0.0156 oz0.0156 oz 33

0.0042 lb0.0042 lb ________

0.000262 mL 0.000262 mL ____

Sandwiched ZerosSandwiched Zeros

RULE 3. Zeros between nonzero numbers are RULE 3. Zeros between nonzero numbers are

significant. (They can not be rounded unless they significant. (They can not be rounded unless they

are on an end of a number.)are on an end of a number.)

Number of Significant Figures

50.8 mm50.8 mm 33

2001 min2001 min 44

0.702 lb0.702 lb ________

0.00405 m0.00405 m ____

Trailing ZerosTrailing Zeros

RULE 4. Trailing zeros in numbers RULE 4. Trailing zeros in numbers

without decimals are NOT significant. without decimals are NOT significant.

They are only serving as place holders.They are only serving as place holders.

Number of Significant Figures

25,000 in 25,000 in 22

200. yr200. yr 33

48,600 gal48,600 gal ________

25,005,000 g 25,005,000 g ________

What are the volumes in the cylinders on

the right?

Remember Sig Fig’s

A B C

BELL RINGER

Significant FiguresSignificant Figures

The numbers reported in a The numbers reported in a measurement are limited by measurement are limited by the measuring toolthe measuring tool

Significant figures in a Significant figures in a measurement include the measurement include the known digits plus one known digits plus one estimated digitestimated digit

Significant Numbers in Significant Numbers in CalculationsCalculations

A calculated answer cannot be A calculated answer cannot be more precise than the measuring more precise than the measuring tool. tool.

A calculated answer must be A calculated answer must be rounded to match the least rounded to match the least precise measurement.precise measurement.

Adding and SubtractingAdding and Subtracting

Only concerned with numbers Only concerned with numbers AFTERAFTER the decimal point. Round the decimal point. Round to the least precise measurement.to the least precise measurement.

25.25.22 one decimal placeone decimal place

+ 1.+ 1.3434 two decimal placestwo decimal places 26.5426.54answer 26.5answer 26.5 one decimal placeone decimal place

Learning CheckLearning Check

In each calculation, round the answer In each calculation, round the answer to the correct number of significant to the correct number of significant figures.figures.A. 235.05 + 19.6 + 2.1 = A. 235.05 + 19.6 + 2.1 =

1) 256.751) 256.75 2) 256.8 2) 256.8 3) 2573) 257

B. 58.925 - 18.2B. 58.925 - 18.2 ==1) 40.7251) 40.725 2) 40.73 2) 40.73 3) 40.73) 40.7

Multiplying and Dividing

Round (or add zeros) to the Round (or add zeros) to the calculated answer until you calculated answer until you have the same number of have the same number of significant figures as the significant figures as the measurement with the measurement with the fewest significant figures.fewest significant figures.

Learning CheckLearning Check

A. 2.19 X 4.2 =A. 2.19 X 4.2 = 1) 91) 9 2) 9.2 2) 9.2 3) 3)

9.1989.198

B. 4.311 ÷ 0.07 =B. 4.311 ÷ 0.07 = 1)1) 61.5861.58 2) 62 2) 62 3) 603) 60

C. C. 2.54 X 0.00282.54 X 0.0028 = = 0.0105 X 0.060 0.0105 X 0.060 1) 11.31) 11.3 2) 112) 11 3) 0.041 3) 0.041

• Law: Repeatedly tested hypothesis that has not been contradicted– Law of Gravity

•Theory: A Unifying Principle that explains Facts and Laws

–Theories are not hypothesis–Continuously revised as new data obtained– Theory of Evolution

• Quantitative vs. Qualitative descriptions

Qualitative

•Red

•Far from Earth

•Microscopic

•Hot

Quantitative

•700nm wavelength

•300 million light yr

•Smaller than 1 μm

•350 °C

–Quantitative•Objective•Measurable•“Brittany’s 100m time is 9.8 sec

–Qualitative•Subjective•Interpretations•“Brittany is fast”

– Precise• Repeatability of a measurement• Does not take into account the real or true

value–Accurate

•Agreement between the measurement and the true or correct value•‘Correct’

•Precision vs. Accuracy

Three Three targets with targets with three arrows three arrows each to each to shoot.shoot.

Can you hit the bull's-eye?Can you hit the bull's-eye?

Both accurate and precise

Precise but not accurate

Neither accurate nor precise

How do How do they they compare?compare?

Can you define accuracy and precision?Can you define accuracy and precision?

Not accurate,

Not precise

Not accurate,

Precise

Accurate,

Precise

Group 1

Group 2 Group 3 Group 4

1.01 g 2.863287 g 1.01325 g 2.05 g

1.03 g 2.754158 g 1.013258 g 0.230 g

0.990 g 2.186357 g 1.013255 g 0.710 g

1.01 g 2.601257 g 1.013255 g 1.01 g

1. Which group(s) are most accurate?

2. Which group(s) are most precise?

3. Which group is the most accurate and precise?

Mass of a paperclip = 1.0003 g

Group 4

Avg. 1.01 g 2.601265g 1.01326g 1.00 g

Group 3

Group 3

Which ruler can be most precise? Accurate?

Ruler A

Ruler B

Ruler C

Which clock can be most precise?

MeasurementMeasurement

What is our system of measurement based What is our system of measurement based upon?upon?

For example, at one time the standard for length was the king’s foot. What are some

problems with this standard?

The distance between Los Angeles and Denver is 1182 miles. How many kilometers

is this?

1km = 3281 ft1182 miles

1x 5280 ft

1 mile

x3281

ft

1 km

= 6240960 km3281

= 1902 km

BELL RINGER

Stating a MeasurementStating a Measurement

In every measurement there is aIn every measurement there is a

Number Number followed by a followed by a

Unit Unit from a measuring devicefrom a measuring device

The number should also be as precise as the

measurement!** Without a unit – your answer is _________!!!!!!!NAKED You have naked

numbers??? Oh, the horror!

MeasuringMeasuringSignificant Figures

A metric ruler

cm. marks

mm. marks

This ruler can measure to the 10th of a

mm

Estimating the last digit in a measurement

You might estimate the end of the cylinder to be half-way between the lines or 0.05 cm. This digit must be included in the measurement.

Estimating the last digit in a measurement

This measurement should be read as 4.95 cm. This measurement has 3 significant figures.

Reading a metric ruler correctly:This point can be read as 1.65 cm. or 16.5 mm.

Reading a metric ruler correctly:This point can be read as 6.70 cm. or 67.0 mm.

Read the cylinder correctly:

We know it is between 35 and 40

We know it is between 36 and 37

Should be read as:

36.4 ml

Read the cylinder correctly:

We know it is between 6 and 8

Should be read as:

6.62 ml

36

Convert 300. seconds to weeks.

300. sec

1x

1 min

60 sec

x60

min

1 hour x

24 hrs.

1 day

x1 week7 days

= 4.96 x 10-4 weeks

BELL RINGER

What is Scientific What is Scientific Notation?Notation?

• Scientific notation is a way of Scientific notation is a way of expressing really big numbers or expressing really big numbers or really small numbers.really small numbers.

• It is most often used in “scientific” It is most often used in “scientific” calculations where the analysis calculations where the analysis must be very precise.must be very precise.

• For very large and very small For very large and very small numbers, scientific notation is numbers, scientific notation is more concise.more concise.

Scientific notation Scientific notation consists of two parts:consists of two parts:

•A number between 1 and 9A number between 1 and 9

•A power of 10A power of 10

N x 10N x 10xx

To change standard form To change standard form to scientific notation…to scientific notation…

• If you make the If you make the numbernumber smallersmaller, then , then

you have to make the you have to make the exponent exponent largerlarger..

• If you make the If you make the number number largerlarger, then you have to make , then you have to make the the exponent smallerexponent smaller..

ExampleExample• Given: 289,800,000• Use: 2.898 (moved 8 places)• Answer: 2.898 x 108

• Given: 0.000567• Use: 5.67 (moved 4 places)• Answer: 5.67 x 10-4

To change scientific To change scientific notation to standard notation to standard

form…form…• Simply move the decimal point Simply move the decimal point

to the right for positive to the right for positive exponent 10. exponent 10.

• Move the decimal point to the Move the decimal point to the left for negative exponent 10.left for negative exponent 10.

(Use zeros to fill in places.)(Use zeros to fill in places.)

ExampleExample• Given: 5.093 x 106

• Answer: 5,093,000 (moved 6 places to the right)

• Given: 1.976 x 10-4

• Answer: 0.0001976 (moved 4 places to the left)

Practice

405789405789

0.0038720.003872

30000000030000000000

22

0.4782600.478260

Express these numbers in Scientific Notation:

(Round to 3 significant digits)4.06 x 1053.87 x 10-

33.00 x 109

2.00 x 100

4.78 x 10-

1

Temperature ConversionsTemperature Conversions

A person with hypothermia has a body A person with hypothermia has a body temperature of 29.1°C. What is the body temperature of 29.1°C. What is the body

temperature in K?temperature in K?

K = ˚C + 273K = ˚C + 273

K = 29.1˚C + 273K = 29.1˚C + 273

K = 302.1K = 302.1

How many seconds are in 1.4 days?

1.4 days

1x

24 hours

1 day

x1

hour

60 min. x

1 min.

60 sec

=120960 sec

1= 1.2 x 105 sec

BELL RINGER

Bell Ringer

How many feet in 0.50 kilometers? Remember Sig Figs

Temperature Temperature ScalesScales

• FahrenheitFahrenheit

• CelsiusCelsius

• KelvinKelvin

Anders Celsius1701-1744

Lord Kelvin(William Thomson)1824-1907

Temperature ScalesTemperature Scales

Notice that 1 kelvin = 1 degree Celsius1 kelvin = 1 degree Celsius

Boiling point Boiling point of waterof water

Freezing point Freezing point of waterof water

CelsiusCelsius

100 ˚C100 ˚C

0 ˚C0 ˚C

100˚C100˚C

KelvinKelvin

373 K373 K

273 K273 K

100 K100 K

FahrenheitFahrenheit

32 ˚F32 ˚F

212 ˚F212 ˚F

180˚F180˚F

Calculations Using Calculations Using TemperatureTemperature

37 ˚C + 27337 ˚C + 273

Generally require temp’s in Generally require temp’s in kelvinskelvins

K = ˚C + 273K = ˚C + 273Body temp =Body temp = = 310 K= 310 K

Liquid nitrogen = -196 ˚CLiquid nitrogen = -196 ˚C + 273 =+ 273 = 77 K77 K

DENSITYDENSITY - an - an important and useful important and useful physical propertyphysical property

Density mass (g)volume (cm3)

Density mass (g)volume (cm3)

Mercury

13.6 g/cm13.6 g/cm33 21.5 g/cm21.5 g/cm33

Aluminum

2.7 g/cm2.7 g/cm33

Platinum

D =

ProblemProblem A piece of copper has a mass of A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density and 0.95 mm thick. Calculate density (g/cm(g/cm33).).

Density mass (g)volume (cm3)

Density mass (g)volume (cm3)

StrategyStrategy1. Get dimensions in common units.1. Get dimensions in common units.

2.2. Calculate volume in cubic Calculate volume in cubic centimeters.centimeters.

3. Calculate the density.3. Calculate the density.

SOLUTIONSOLUTION1. Get dimensions in common units.1. Get dimensions in common units.

2.2. Calculate volume in cubic Calculate volume in cubic centimeters.centimeters.

3. Calculate the density.3. Calculate the density.

0.95 mm • 1cm

10 mm = 0.095 cm

57.54 g

6.4 cm3 = 9.0 g / cm3

(9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm(9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm33

Note only 2 significant figures in the answer!Note only 2 significant figures in the answer!

What is the length of the green line?What is the length of the green line?

. l3. . . . I . . . . I4 . . . . I . . . . I5. . cm

Bell Ringer

You need to know for the exam

•Precision & Accuracy

•Element Symbols 1-18

•Significant Digits

•Metric System

•Scientific Method

•Scientific notation

•Conversions

•What is Chemistry

•Labs that we have done so far

Bell Ringer

What is Chemistry?

How many yards in a mile?

BELL RINGER

What is the name of this

flask?

BELL RINGER

What is 7.9 seconds in weeks?

7.9 sec

1x

1 min

60 sec

x60

min

1 hour x

24 hours

1 day

x1 week

7 day= 1.31 x 10-5

sec

BELL RINGER