Chapter OneChapter One

INTRODUCTION TO INTRODUCTION TO CHEMISTRYCHEMISTRY

MondayMonday Scientific method foldableScientific method foldable Variables foldableVariables foldable

Section 1.2 Section 1.2 Chemistry and MatterChemistry and Matter Chemistry-Chemistry- Study of matter Study of matter

and changes it undergoesand changes it undergoes Matter-Matter- anything that has anything that has

mass and takes up spacemass and takes up space

What’s the difference What’s the difference between mass and weight???between mass and weight???

Mass-Mass- the amount of matter in the amount of matter in an objectan object

Weight-Weight- measure of matter measure of matter and effect of gravity on an and effect of gravity on an objectobject

What do the prefixes macro- What do the prefixes macro- and micro- mean???and micro- mean???

Macroscopic-Macroscopic- do not need a do not need a microscope to see itmicroscope to see it

Submicroscopic-Submicroscopic- so tiny that so tiny that parts can’t even be seen with parts can’t even be seen with microscope (ex: atom)microscope (ex: atom)

Submicroscopic events are Submicroscopic events are explained by making explained by making modelsmodels (a visual, verbal, or (a visual, verbal, or mathematical explanation of mathematical explanation of how things occur)how things occur)

Section 1.3Section 1.3Scientific MethodsScientific Methods

Scientific Scientific Method-Method- a a systematic systematic approach approach used in all used in all scientific studyscientific study

Steps of Scientific Steps of Scientific MethodMethod

1. 1. Observation- the Observation- the act of gathering act of gathering informationinformation; may ; may be be qualitative dataqualitative data (from 5 senses) or (from 5 senses) or quantitative dataquantitative data (numerical (numerical information) information)

2. 2. Formulate Formulate hypothesishypothesis (testable statement or (testable statement or prediction about what has prediction about what has been observed)been observed)

33. . Conduct Conduct ExperimentExperiment (set of (set of controlled observations that controlled observations that test hypothesis)test hypothesis)

Variables Variables

Independent and Dependent Independent and Dependent Variables:Variables:

What they mean and how to use What they mean and how to use themthem

What is a variable?What is a variable?

In the design of a scientific experiment, a In the design of a scientific experiment, a variable is any factor that changes from variable is any factor that changes from data group to data groupdata group to data group..

Scientific experiments are designed so Scientific experiments are designed so that the tested variables are the only that the tested variables are the only things that are supposed to change from things that are supposed to change from group to group; all other factors are to group to group; all other factors are to remain constantremain constant

A handy Mnemonic for A handy Mnemonic for VariablesVariables

Remember this phrase:Remember this phrase:

DRY MIXDRY MIX

Dependent VariableDependent Variable

DDependent Variableependent Variable is the variable that is the variable that RResponds to the esponds to the

experimental designexperimental design and is graphed on the and is graphed on the YY--axisaxis

Independent VariableIndependent Variable

The variableThe variable MManipulated by the anipulated by the scientistscientist

is called theis called the IIndependent variablendependent variable and is graphed on the and is graphed on the XX--axisaxis

Constant – variable that does not Constant – variable that does not change during an experimentchange during an experiment

ControlControl- standard - standard for comparisonfor comparison

For Example:For Example:

John wants to test how outside temperature John wants to test how outside temperature effects pea plant growth. He sets up four effects pea plant growth. He sets up four identical greenhouse boxes where the only identical greenhouse boxes where the only difference in the plant environments will be difference in the plant environments will be ambient temperature. One plant will grow at 10 ambient temperature. One plant will grow at 10 °C. Another will grow at 20 °C which is room °C. Another will grow at 20 °C which is room temperature. A third will grow at 30 °C. Finally, temperature. A third will grow at 30 °C. Finally, a forth will grow at 50 °C. After 30 days, the a forth will grow at 50 °C. After 30 days, the pea plants were measured for growth.pea plants were measured for growth.

Data TableData Table

Temperature (in °C) Pea Plant Growth (in cm)10 1320 4530 3750 4

GraphGraph

0

10

20

30

40

50

10 20 30 50

Plan

t Gro

wth

(cm

)

Temperature (°C)

Pea Plant Growth

Pea Plant Growth (in cm)

4. 4. Analyze the data Analyze the data (more to (more to come in chapter 2)come in chapter 2)

5. 5. Form a Form a conclusionconclusion (judgment (judgment based on the information based on the information obtained; comparison of obtained; comparison of hypothesis with actual resultshypothesis with actual results))

TheoryTheory- - explanation supported explanation supported by many, many experimentsby many, many experiments

Ex: Big Bang TheoryEx: Big Bang Theory

Scientific Law-Scientific Law- when the same when the same conclusion is found many conclusion is found many times with no exceptionstimes with no exceptions

Ex: Newton’s Law of MotionEx: Newton’s Law of Motion

Scientific Method and Law

DiscussionDiscussion

Which variable was the independent Which variable was the independent variable?variable?

Which variable was the dependent Which variable was the dependent variable?variable?

Which plant represented the control Which plant represented the control group?group?

TuesdayTuesday

Correct variables worksheetCorrect variables worksheet Scientific notationScientific notation Significant figuresSignificant figures Accuracy and precisionAccuracy and precision

Chapter 2Chapter 2

Data AnalysisData Analysis

2.1 Units of 2.1 Units of MeasurementMeasurement

In 1960 the metric system was In 1960 the metric system was updated and is called the updated and is called the Systeme Internationale d’Unites Systeme Internationale d’Unites or the SI unit of measurementor the SI unit of measurement..

Standard units of measurement Standard units of measurement for ALL scientists to use for ALL scientists to use worldwide.worldwide.

Base UnitBase Unit - - unit of unit of measurement based on an measurement based on an object or event in the object or event in the physical worldphysical world

The standard kilogram is stored in a vault at the International Bureau of Weights and Standards near Paris. It is made of a platinum-iridium alloy, and is shown here next

to an inch-based ruler for scale.

Base Units:Base Units:1. Time: 1. Time: secondsecond (s) (s)

2. Length: 2. Length: metermeter (m) (m)

3. Mass: 3. Mass: gramgram (g) (g)

4. Temperature: Kelvin 4. Temperature: Kelvin

(K)(K)

5. Amount of substance: 5. Amount of substance:

mole (mol) mole (mol) an international an international

standard to measure an "amount standard to measure an "amount

of stuff" aka Mole! It refers to the of stuff" aka Mole! It refers to the

number of atoms in 12 grams of number of atoms in 12 grams of

carbon 12 (6.022 x 10carbon 12 (6.022 x 102323) )

Avagadro’s NumberAvagadro’s Number

Derived UnitDerived Unit - - A unit that is A unit that is a combination of base a combination of base unitsunits..

There are hundreds of units There are hundreds of units needed for measuring needed for measuring “everything,” but they are all “everything,” but they are all derived from those base units.derived from those base units.

1.1. Volume = L x W x H for a Volume = L x W x H for a regularly regularly shaped solidshaped solidcubic meter (mcubic meter (m33),cubic centimeter ),cubic centimeter (cm(cm33) or cubic decimeter (dm) or cubic decimeter (dm33))

Unit for volume: Unit for volume: literliter (L) for a (L) for a liquidliquid 1 dm1 dm33 = 1 L 1 cm = 1 L 1 cm3 3 = 1 mL = 1 mL

2.2. Density-Density- ratio that compares ratio that compares the mass of an object to its the mass of an object to its volumevolume

Units are grams per cubic Units are grams per cubic centimeter (g/cmcentimeter (g/cm33))

1 ml = 1 cm1 ml = 1 cm33

density = density = massmass volumevolume

Density is a Density is a property that can property that can be used to identify be used to identify an unknown an unknown sample of matter.sample of matter.

TemperatureTemperature KelvinKelvin – SI base unit – SI base unit

for temperaturefor temperature ºC + 273 = KºC + 273 = K K – 273 = ºC K – 273 = ºC There are no There are no

negative negative temperatures in temperatures in KelvinKelvin

2.2 Scientific Notation2.2 Scientific Notation Scientific Notation-Scientific Notation- expresses numbers expresses numbers

as a multiple of two factors: as a multiple of two factors:

1. A number between 1 and 91. A number between 1 and 9

2. Ten is raised to a power (exponent).2. Ten is raised to a power (exponent). 2.0 x 102.0 x 1033 3 is the exponent 3 is the exponent

2.0 x 102.0 x 1033 = 2000 = 2000 .20 or 20 would be WRONG because they .20 or 20 would be WRONG because they

are NOT numbers between 1 and 10!!are NOT numbers between 1 and 10!!

Scientific Notation Scientific Notation ExampleExample

Count the number of places the decimal point moved Count the number of places the decimal point moved andand the the directiondirection

Convert 436289 to scientific notation.Convert 436289 to scientific notation.

1.1. Place decimal at end of number Place decimal at end of number 436289436289..

2.2. Move decimal to place it behind the first number Move decimal to place it behind the first number 44..36289 36289

3.3. YouYou moved the decimal 5 places moved the decimal 5 places left. left.

4.4. If decimal moves If decimal moves left,left, the exponent is positive the exponent is positive

5.5. The # of times the decimal was moved becomes the The # of times the decimal was moved becomes the exponent.exponent.

4.36289 x 104.36289 x 1055

If decimal moves left, If decimal moves left, exponent is positiveexponent is positive

if decimal moves right, if decimal moves right, exponent is negativeexponent is negative

Convert Convert .000872 .000872 to scientific notationto scientific notation

1.1. Move the decimal behind first number that is Move the decimal behind first number that is NOT a zero. NOT a zero. 00080008..72 72

2.2. 8.72 You moved the decimal 4 places 8.72 You moved the decimal 4 places right. right.

3.3. The # of times the decimal was moved The # of times the decimal was moved becomes the exponent.becomes the exponent.

4.4. If decimal moves If decimal moves right,right, exponent is negative. exponent is negative.

5.5. The # of times the decimal was moved The # of times the decimal was moved becomes the negative exponentbecomes the negative exponent

8.72 x 10 8.72 x 10 – 4– 4

To convert Scientific Notation to To convert Scientific Notation to Standard Notation Reverse the Standard Notation Reverse the above steps:above steps: If the exponent is positive move the decimal If the exponent is positive move the decimal

to the right the same number of places as the to the right the same number of places as the exponent.exponent.

2.5 x 102.5 x 104 4 = 25 000 = 25 000

If the exponent is negative move the decimal If the exponent is negative move the decimal to the left the same number of places as the to the left the same number of places as the exponent.exponent.

2.5 x 102.5 x 10-4 -4 = .00025= .00025

Adding, subtracting, Adding, subtracting, multiplying, and dividing in multiplying, and dividing in Scientific Notation by using Scientific Notation by using the calculatorthe calculatorUse “EE” or “exp” key on your Use “EE” or “exp” key on your

calculator to replace “ x 10^”calculator to replace “ x 10^”Ex: 8.72 x 10Ex: 8.72 x 10-4-4 would be would be

8.72”EE”-48.72”EE”-4

Sect. 2.3: How reliable Sect. 2.3: How reliable are measurements?are measurements?

AccuracyAccuracy – how close a measured – how close a measured value is to an accepted or true value is to an accepted or true valuevalue

PrecisionPrecision – how close a series of – how close a series of measurements are to each othermeasurements are to each other

Compare to throwing darts bottom Compare to throwing darts bottom of pg 36.of pg 36.

ACCURACY VS. PRECISION:ACCURACY VS. PRECISION:

HOWEVER, if the actual time is 3:00, then the second clock is HOWEVER, if the actual time is 3:00, then the second clock is more more accurate accurate than the first one. than the first one.

ACCURACY = HOW CLOSE A MEASUREMENT IS TO ACCURACY = HOW CLOSE A MEASUREMENT IS TO THE TRUE VALUETHE TRUE VALUE

PRECISION = EXACTNESSPRECISION = EXACTNESS

THIS CLOCK is more precise than THIS CLOCK

Percent errorPercent error – the ratio of an error to an – the ratio of an error to an accepted value.accepted value.

% error = % error = experimental – acceptedexperimental – accepted x 100 x 100 accepted valueaccepted valueExample:Example:Density of lead is 11.3, you had 10.3 in Density of lead is 11.3, you had 10.3 in

your experiment.your experiment.Difference is 1 Difference is 1 So So 1 1 x 100 = 8.8% x 100 = 8.8% 11.311.3

Significant FiguresSignificant Figures Accuracy is limited by the available tools.Accuracy is limited by the available tools. Sig figs are based on instrument precision (numbers Sig figs are based on instrument precision (numbers

can only be as exact as the instrument is)can only be as exact as the instrument is) Instruments must be calibrated to assure accuracy.Instruments must be calibrated to assure accuracy.

The “best” number is the one with The “best” number is the one with the most decimal places.the most decimal places.

So 3.54 g is MORE precise So 3.54 g is MORE precise

than 3.5 g.than 3.5 g.

Significant figuresSignificant figures - include all - include all known digits plus ONE estimated known digits plus ONE estimated digit.digit.

Having Trouble with Sig Figs? Having Trouble with Sig Figs? Try this:Try this:1. Determine if the decimal point is “present” or “absent”.1. Determine if the decimal point is “present” or “absent”.2. Picture a map of the U.S. with the Pacific Ocean on the left 2. Picture a map of the U.S. with the Pacific Ocean on the left

and the Atlantic Ocean on the right. and the Atlantic Ocean on the right.

PACIFICPACIFIC ATLANTICATLANTICDecimal presentDecimal present Decimal absentDecimal absent

3. If the decimal point is “present”, imagine an arrow LEFT 3. If the decimal point is “present”, imagine an arrow LEFT from the Pacific Ocean pointing to the number. (Think “P” from the Pacific Ocean pointing to the number. (Think “P” for “present” and “Pacific”). for “present” and “Pacific”).

4. If the decimal point is “absent”, imagine an arrow RIGHT 4. If the decimal point is “absent”, imagine an arrow RIGHT from the Atlantic Ocean pointing to the number (“A” for from the Atlantic Ocean pointing to the number (“A” for “absent” and “Atlantic”). “absent” and “Atlantic”).

5. Start counting digits when the arrow hits a non-zero digit. 5. Start counting digits when the arrow hits a non-zero digit. Each digit after that is significant.Each digit after that is significant.

EXAMPLES:EXAMPLES:

..000099120 has 4 sig figs (9 is the first 120 has 4 sig figs (9 is the first non-zero digit counting from Pacific)non-zero digit counting from Pacific)

11..050 has 4 sig figs (1 is the first 050 has 4 sig figs (1 is the first non-zero digit counting from Pacific)non-zero digit counting from Pacific)

3400340055 has 5 sig figs (5 is the first has 5 sig figs (5 is the first non-zero digit counting from Atlantic)non-zero digit counting from Atlantic)

112200 00 has 2 sig figs (2 is the first has 2 sig figs (2 is the first non-zero digit counting from Atlantic)non-zero digit counting from Atlantic)

Rounding NumbersRounding Numbers

If last number is five or If last number is five or greater, round up. 12.6 13greater, round up. 12.6 13

If last number is less than If last number is less than five, leave alone.five, leave alone.

12.2 1212.2 12

Rounding Examples Rounding Examples 12.2784512.27845Round to 3 significant figuresRound to 3 significant figures

12.312.3Round to 5 significant figuresRound to 5 significant figures

12.27812.278Round to 4 significant figuresRound to 4 significant figures

12.2812.28Round to 2 significant figuresRound to 2 significant figures

1212

Math with Sig FigsMath with Sig Figs When adding/subtracting, When adding/subtracting,

answer will be rounded to least answer will be rounded to least number of decimal placesnumber of decimal places

28.0 cm 28.0 cm 23.538 cm23.538 cm

++ 25.68 cm 25.68 cm

77.218 cm 77.218 cm so the answer must have so the answer must have only one digit to the right of the decimalonly one digit to the right of the decimal

77.2 cm is the answer77.2 cm is the answer

When multiplying/dividing, answer will When multiplying/dividing, answer will be rounded to be rounded to least number of sig least number of sig figsfigs

3.20 cm x 3.65 cm x 2.05 cm 3.20 cm x 3.65 cm x 2.05 cm == 23.944 23.944 cmcm33

all the factors have 3 sig figs all the factors have 3 sig figs

So the answer should have 3 sig figsSo the answer should have 3 sig figs

23.944 cm23.944 cm33 Becomes Becomes 23.9 cm23.9 cm3 3

Mult/Div Round to the Mult/Div Round to the least number of sig figsleast number of sig figs 2.50 m x 0.05 m x 5.00 m = 2.50 m x 0.05 m x 5.00 m = 0.625 m0.625 m33

3 sig figs3 sig figs 1 sig fig 1 sig fig 3 sig figs 3 sig figs

The answer should have The answer should have oneone sig fig. sig fig.

The answer would be 0.6 mThe answer would be 0.6 m33

(1200 cm (1200 cm ..//.. 3.0 cm) 3.0 cm) ..//.. 400.0 cm = 400.0 cm = 1 cm1 cm33

2 sig figs2 sig figs 2 sig fig 2 sig fig 4 sig figs 4 sig figs

The answer should have 2 sig figsThe answer should have 2 sig figs

The answer would be 1.0 cmThe answer would be 1.0 cm33

WEDNESDAYWEDNESDAY

Practice significant figures and scientific Practice significant figures and scientific notation worksheetnotation worksheet

ThursdayThursday

Grade worksheetGrade worksheet Do graph foldableDo graph foldable

Section 2.4: Section 2.4: Representing DataRepresenting Data

A goal of many experiments is to A goal of many experiments is to discover whether a pattern exits.discover whether a pattern exits.

Data in a table may not show an Data in a table may not show an obvious pattern.obvious pattern.

Graphing can help reveal a Graphing can help reveal a pattern. pattern.

GraphsGraphs GraphGraph – visual display of data – visual display of data 4 types of Graphs4 types of Graphs

Circle graph/pie chartCircle graph/pie chartBar GraphBar GraphLine GraphLine GraphScatter PlotScatter Plot

HOW TO CHOOSE WHICH HOW TO CHOOSE WHICH TYPE OF GRAPH TO USE?TYPE OF GRAPH TO USE?

When to Use a Pie Chart.When to Use a Pie Chart. a “part of a whole” or as

percentages

When to Use . . .When to Use . . .. . . a Bar Graph. . . . a Bar Graph.

used to show how a used to show how a quantity changes with quantity changes with certain factors certain factors

to to comparecompare things things between different between different groups groups

to track changes over to track changes over timetime

Bar graphs are best Bar graphs are best when the changes are when the changes are largerlarger..

ScatterplotScatterplot

A scatter plot is a A scatter plot is a graph of a collection of graph of a collection of ordered pairs (x,y).ordered pairs (x,y).

The graph looks like a The graph looks like a bunch of dotsbunch of dots, but , but some of the graphs are some of the graphs are a general shape or a general shape or move in a general move in a general directiondirection

When to Use . . .When to Use . . .. . . a Line graph. . . . a Line graph.

used to track used to track changes over changes over shortshort and and long periodslong periods of timeof time

When When smaller smaller changes existchanges exist, line , line graphs are better to graphs are better to use than bar graphsuse than bar graphs

used to compare used to compare changes over the changes over the same period of time same period of time for more than one for more than one groupgroup

Distance /Time GraphDistance /Time Graph

When Are Histograms When Are Histograms Used?Used?

• • Summarize large data sets graphicallySummarize large data sets graphically • • Compare measurements to Compare measurements to

specificationsspecifications • • Communicate information to the teamCommunicate information to the team • • Assist in decision makingAssist in decision making

FridayFriday

Measurement LabMeasurement Lab