Today…



Turn in:

Fill out Goal Sheet and turn in (enter scores and calculate grade)
Our Plan:

Elements Song



Review – Quiz, Quiz Trade
Symbols Quiz
New Calendar/Goal Sheet


Notes – Scientific Notation, Accuracy, Precision, Percent Error
Worksheet #1

Wrap Up: Online Quiz
Homework (Write in Planner):


Complete WS #1 by next class
2 nd Symbols Quiz Next Time

Block
A B C D F
Ave
High
Score
1 3 3 6 5 5
70.43
94 (x3)
2 8 7 6 2 4
80.15
98 (x2)
5 7 3 7 7 2
75.62
100
6 9 8 6 2 4
79.72
94 (x2)
TOTAL 26% 20% 24% 15.5% 14.5%

http://www.youtube.com/watch?v=GFIvXVMbII0
Element Song

Quiz, Quiz, Trade

Ready for the Symbols Quiz?



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





I
U
K
Xe
Fe
Ag
H
He
O
Ar
Iron
Silver
Hydrogen
Helium
Oxygen
Argon
Potassium
Xenon
Iodine
Uranium










Magnesium
Aluminum
Zinc
Gold
Phosphorus
Carbon
Francium
Calcium
Boron
Lithium
P
C
Fr
Ca
B
Li
Mg
Al
Zn
Au


This text message is too long. In the space provided in your notebooklet, write it as short as possible, but make sure it still has the same meaning…

Hello Mrs. Chamberlain, I need your help! I do not know what time school starts tomorrow.
Thank you.


The number
602200000000000000000000 is used so frequently in chemistry that it has its own name;
Avogadro’s number. What would be a better way of writing it?


To write a number in scientific notation:
1.
2.
3.
Move the decimal so that the number is between 1 and 10.
The exponent is the number of tens places you moved the decimal
Moving the decimal right = - exponent
Moving the decimal left = + exponent


65000 m =
6.5 x 10 4 m

0.0000156 s =
1.56 x 10 -5 s

0.24 m/s =
2.4 x 10 -1 m/s

6.7 mm =
6.7 x 10 0 mm



Change it from scientific notation to a standard number by moving the decimal.
Example
1.4 x 10 6 = 1,400,000
2.6 x 10 -4 = 0.00026


Change the numbers to the same exponent.

Add or subtract the numbers

Example: 4.1 x 10 6 + 8.5 x 10 7

0.41 x 10 7 + 8.5 x 10 7 = 8.91 x 10 7


Multiply the numbers

Add the exponents

Example: (4 x 10 6 )(2 x 10 8 )

8 x 10 14


Divide the numbers

Subtract the exponents

Example: (9 x 10 7 )/(3 x 10 4 )

3 x 10 3

1.
2.
3.
4
5
8
6
6
3

1.
2.
3.
5.45 x 10 5
1.995 x 10 15
1.53 x 10 3


Use your scientific calculator.

The EE button means x10 ^

Do the Try it Out problems again using your calculator and see if you get the correct answers!


Accuracy – a measure of how close a measured value is to the actual value

Example: If a weight is labeled
5 g and a balance reads 5 g when you place it on it, the balance is accurate .


P recision – a measure of the reproducibility of a measurement.

It is how close a series of measurements are to one another.

Example – If I find the mass of a
5g weight on a balance 3 times and
I get 4.99g each time it is precise .




High precision is denoted by a large number of significant figures (decimal places).
Typically, high quality instruments measure things with high precision and accuracy.
That’s why a lab balance costs $300 + and your bathroom scaled costs $8.

Accurate, Precise, Both, Neither?
Accurate

Accurate, Precise, Both, Neither?
Precise

Accurate, Precise, Both, Neither?
Neither

Accurate, Precise, Both, Neither?
Precise

Accurate, Precise, Both, Neither?
Both

Accurate, Precise, Both, Neither?
Accurate

Percent Error = |experimental - actual| actual value
X 100

The absolute value is present so that percent error is always POSITIVE!

Example

Working in the laboratory, a student finds the density of a piece of pure aluminum to be 2.85 g/cm 3 . The accepted value for the density of aluminum is 2.699 g/cm 3 . What is the student's percent error?
Percent Error = |2.85 – 2.699|
2.699
X 100 =
5.59%

Try It Out

A student takes an object with an accepted mass of 200.00 grams and masses it on his own balance. He records the mass of the object as
196.5 g. What is his percent error?
Percent Error = |196.5 – 200.00|
200.00
1.75%
X 100 =



Complete Worksheet #1 by next class
Worksheets are…




A completion grade (i.e. You do not get a grade until it is 100% finished)
10 points at beginning of class
9 points late on due date
-2.5 points each day it’s late


Online Scientific Notation Quiz http://www.sciencegeek.net/Act ivities/scientificnotation.html

Get Mrs. C’s signature on your
Worksheet after you complete
15 correctly.

Today…



Turn in:

Get out WS#1 to Check

Fill out Bingo Card with any symbols
Our Plan:




Symbols Review – Bingo
Symbols Quiz #2
Scientific Notation Clicker Review
Scientific Notation Quiz


Notes – Significant Figures/Units of Measurement
WS #2

Bluff
Homework (Write in Planner):


Complete WS #2 by next class (9/12)
QUIZ OVER SIG FIGS NEXT TIME!

Even toddlers learn their element symbols…
 http://www.youtube.com/watch?v=z_6 u1njmX8g

Intro to Units & Sig Figs
 http://www.youtube.com/watch?v=hQp
Q0hxVNTg&feature=share&list=UUX6b
17PVsYBQ0ip5gyeme-Q

Units in Chemistry



When you add or subtract two numbers, they must have the same units.
The answer then has those units as well.
Example: 4 m + 12 m = 16 m

Units in Chemistry




When you multiply, you also multiply the units.
Examples:

4 m x 5 m = 20 m 2

2 g x 3 s = 6g·s
When you divide, you also divide the units.
Examples:

4 m / 2 s = 2 m/s

8 g / 2 mL = 4g/mL


What does the word
“significant” mean?



Why do we need significant figures?




Because we live in the real world!
Although we can imagine finding a measurement to perfect accuracy with some hypothetical instrument, we never actually do because real instruments aren’t infinitely accurate.
Because our instruments aren’t perfect, it’s important that we somehow indicate how good our instruments are to anybody looking at our data.
We do this by limiting the number of digits we write in a measured number to the significant figures.

An example…


If I told you that I weigh 80.6388154 kilograms, you’d probably assume that I gave you all of those numbers after the decimal place because I weighed myself on a special scale that can measure to that precision.
You wouldn’t assume that I used my bathroom scale, because it would never give you a reading with that many digits (it’s not that precise).



***All nonzero numbers are significant***
125, 689 has 6 significant figures (sig figs)
156 has 3 sig figs
1.
Zeros between nonzero numbers are significant.



2.
Zeros in front of nonzero numbers are not significant



3.
Zeros at the end of a number and to the right of a decimal are significant



4.
Zeros at the end of a number are NOT significant. If there is a decimal at the end, they
ARE.

Decimal
Start at the first nonzero number on the left and count every number right
No
Decimal
Start at the first nonzero number on the right and count every number left

Unlimited Significant Figures


Counting – There are 23 students in the classroom

Could also be expressed as 23.0 or
23.00000000000000 etc.
Conversion Factors – 60 min = 1 hour

Exact quantities do not affect the process of rounding

4.
5.
6.
2.
3.

1.
How many sig figs?
0.00125
3
1.12598000
3,000 1
0.0100103
6
9
5,500.
4
1.23 x 10 5 3

Rounding Tips




When rounding a large number, consider it in terms of owing someone money.
If I owed you $4567 and I want to round that to 1 significant figure, you would not want me to round it to $5.
The correct way to round it would be $5000.
And remember, a 5 or larger after the place/digit you are rounding to means that you round up.

2.
3.
4.

1.
Round the following numbers so that they have 3 significant figures:
1.36579 = 1.37
120 = 1.20 x 10 2 OR 120.
145,256,987 = 145,000,000
0.0001489651 = 0.000149

To Multiply & Divide
Sig Figs…
1.
2.
Count the number of sig figs in each number
Round the answer so that it has the same number of sig figs as the number in the problem with the fewest.




16.19 g / 4.2 mL
= 3.8547619 g/mL
16.19 has 4 sig figs
4.2 has 2 sig figs, so the answer should have 2 sig figs
3.9 g/mL


9.3 m x 0.00167 m
= 0.015531m
2


9.3 m has 2 sig figs, 0.00167 has 3 sig figs
Therefore, the answer must have only 2 sig figs.
0.016 m 2




0.014
0.1
(1.23 x 10 6 )(3.5 x 10 4 ) = 4.3 x 10 10

6.988 x 10 -4

Stop



Complete the two online quizzes and get
Mrs. C’s signature on each.

Today…



Turn in:

Get out WS#2 to Check
Our Plan:

Sig Figs Worksheet Race


Sig Fig Quiz
Notes – Significant Figures in Measurement


Practical Lab - Measurement
Wrap Up – Measure Up
Homework (Write in Planner):

Read Section 3.2 & Fill out p. 10 & 11 of your notes


When doing any measurements in chemistry, it is important that you use the correct precision.

All measurements should be made by writing all units you know and estimating the last unit.

10
10
20
30
20
30
40
50
40
50
60
60
70
54
38
70
13.9
2 4 6 8 10 12 14

2 4 6
3.4
1.16
0.5
1 1.5
72
20 40 60





2
0.5
4 5 6
1 1.5
20 40 60
5.3
1.58
43

Today…



Before Class:

Get out Note Booklet and open to p. 11
Our Plan:





Mix/Group Review (#1-11)
Practical Lab
Challenge
Notes - Conversions
WS #3

Wrap Up – How many cheetos tall are you?
Homework (Write in Planner):

Complete WS #3 by next class



How many sig figs:
1.
102.32500
2.
3.
560.
0.0012501
Write in scientific notation:
4.
420=
5.
36,000,000
6.
60 =


Round these numbers so that they have 3 sig figs:
7.
8.
103,250
567.9
103,000 or 1.03 x 10
568 or 5.68 x 10 2
5
9.
10.
11.
0.0012561
0.00126 or 1.26 x 10 -3
100 100. or 1.00 x 10 2
Read the measurement below correctly.
43
20 40 60


Complete the Practical
Measurement Activity with a
Partner.

Today…



Before Class:

Get out Stop the Process
Our Plan:


Answer Mix/Group Review p. 13 (#1-11)
Challenge/Video


Notes - Conversions
WS #3

Wrap Up – How many cheetos tall are you?
Homework (Write in Planner):

Complete WS #3 by next class





How old are you, in minutes?


Definition: a ratio of equivalent units


It is always equal to 1
When multiplying by a conversion factor, the numerical value is changed, but the actual size of the quantity remains the same




When working with conversion factors, we use the Factor-Label
Method (dimensional analysis)
The factor is the number that explains the relationship between two things
The labels are its’ units


4 quarters = 1
1 dollar
OR
Factor
1 dollar = 1
4 quarters
Label

12 months = 1
1 year
1 foot = 1
12 inches

Rules for using Conversion
Factors
1.
2.
3.
Always start by writing what you know from the problem.
Multiply by a conversion factor so that the units cancel out (same unit in numerator and denominator)
Continue converting until your answer is in the desired units .

Example 1 – your age in minutes
Checklist:
 I started by writing what I knew
 All units cancel
 My answer is in minutes

Mrs. C’s top 4 reasons for NOT using the Factor-Label Method
1.
2.
You’re super-intelligent and enjoy solving relatively simple problems in the most complex manner.
You're tired of always getting the correct answers.

Mrs. C’s top 4 reasons for NOT using the Factor-Label Method
3.
You’re artistic, and rather than using Mrs. C’s concretesequential method of solving problems you want to use your own random method such that you create abstract patterns and designs on paper that you might be able to sell as artwork.

Mrs. C’s top 4 reasons for NOT using the Factor-Label Method
4.
Let's say that you have no interest in going to the prom or making the soccer team, and you don't mind being unpopular, unattractive, ignorant, insecure, uninformed, and unpleasant.
Otherwise,
You Need the Factor-Label Method!

Testimonials

"I was a South High School student who dozed off while Mrs. C taught us the Factor-Label method in chemistry. I never quite got the hang of it. It irritated me... all of those fractions. I never really liked fractions. Although my grades had been pretty high, I got a D in chemistry and subsequently did not take any more high school science classes. It was not long before I started on drugs, and then used crime to support my drug habit. I have recently learned the factor-label method and realize how simply it could have solved all of my problems. Alas, it is too late. I won't get out of prison until 2022 and even then, my self image is permanently damaged. I attribute all of my problems to my unwillingness to learn the factorlabel method ." -Jane

Testimonials

"I thought I knew everything and that sports was the only thing that mattered in high school. When Mrs. C taught our class the factor-label method, I didn't care about it at all. I was making plans for the weekend with my girlfriend who loved me because I was a running back and not because of chemistry. While other kids were home solving conversion problems, I was practicing making end sweeps. Then one day I was hit hard. Splat. My knee was gone. I was a total loser. My girl friend deserted me. My parents, who used to brag about my football stats, stopped loving me and started getting on my case about grades. I decided to throw myself into my school work. But I couldn't understand anything. I would get wrong answers all of the time. I now realize that my failure in school came from never having learned the factor-label method . I thought everyone else was smarter than me. After the constant humiliation of failing I finally gave up. I am worthless. I have no friends, no skills, no interests. I have now learned
is too late." -Bill the factor-label method , but it


How many dollars do you have if you have 38 quarters?
9.5 dollars


How many nanoseconds are in one week?
600,000,000,000,000 nanoseconds


How many milligrams are in 12 g?
12,000 mg


Now try the next three problems in your notes on your own.
Checklist:
 I started by writing what I knew
 All units cancel
 My answer is in desired units

1.
2.
3.
790,000,000 seconds
6.71 x 10 3 grams
5.3 x 10 3 mL




Wrap Up – How Tall are YOU in Cheetos?

Today…



Turn in:

Get WS #3 out to be graded

Booklet p. 15: On Mrs. C’s birthday she will be 1.104 x 10 9 seconds old.
How many years old will she be?
Our Plan:

Fun Review Problem/Questions on WS


Notes - Density
WS #4


Measurement & Density Lab
Clicker Review
Homework (Write in Planner):


Complete WS #4 by next class (9/14 or 9/15)
QUIZ OVER WS#3 & #4 NEXT TIME!


Your car's gas tank holds 18.6 gallons and is one quarter full. Your car gets 16 miles/gal. You see a sign saying, "Next gas 73 miles." Your often-wrong brother, who is driving, is sure you'll make it without running out of gas. You're not so sure and do some quick figuring. Can you make it?

Questions on the Worksheet?






A bar of silver has a mass of 68.0 g and a volume of 6.48 cm 3 .
What is the density of silver?

10.5 g/cm 3


A copper penny has a mass of 3.1 g and the density of copper is
8.8571 g/cm 3 . What is the volume of the penny?

0.35 cm 3


What is the mass of a pure silver coin that has a volume of 1.3 cm 3 ? The density of silver is 10.5 g/cm 3 .

14 g

Using density as a conversion factor.

What volume of ethanol (in Liters) would you have if you acquire 126.56 g of ethanol? The density of ethanol is
0.789 g/cm 3 .

0.16032 L

Try it Out!

The density of apples is 0.641 g/cm 3 . If an apple has a mass of 0.089 kg, what is its volume?

140 cm 3



Today…



Turn in:


Get WS #4 out to be graded
Complete Review p. 17
Our Plan:

Conversions & Density Quiz


Lab
Wrap Up: Rally Robin
Homework (Write in Planner):

Missing Work!

Review – Which Word Am I
(p. 15 Notes)
1.
2.
4.
5.
6.
3.
Mass divided by volume
The numbers that are known in a measurement plus one estimated digit
How close your measurements are to the true value
How close your measurements are to each other
Convert 3.69 meters into inches.
What is the volume of a cube that has a mass of
7.9 g and a density of 9.45 g/cm 3 ?

Wrap Up

Rally Robin


Pair up with your shoulder partner.
Divide a deck of cards in half. Take turns asking each other the questions on the cards.
Be sure to cover the answer with your finger.

Today…



Turn in:

Do the density review problem on p. 18
Our Plan:

LAB – DUE TODAY


Work Day


Missing Work
Test Review
Wrap Up: Bluff
Homework (Write in Planner):

Test Review due next class

TEST NEXT TIME!







Four graduated cylinders each contain a different liquid: A, B, C, and D.
Liquid A: mass = 18.5 g; volume = 15.0 mL
Liquid B: mass = 16.5 g; volume = 8.0 mL
Liquid C: mass = 12.8 g; volume = 10.0 mL
Liquid D: mass = 20.5 g; volume = 12.0 mL
Examine the information given for each liquid, calculate the density, and predict the layering of the liquids if they were carefully poured into a larger graduated cylinder.

A – 1.23 g/mL
Density = Mass/Volume
C – 1.28 g/mL
D – 1.71 g/mL
B – 2.1 g/mL

1A. How many sig figs are in 0.001023?
1B. Solve 456 x 3.2
2A. How many sig figs would the answer have if you calculated 2.1 x 0.01?
2B. How many sig figs are in 123,000?
3A. Solve 2.7 x 3
3B. How many sig figs would the answer have if you calculated 1.4/3.789?

4A. What is 235,489 rounded to 2 sig figs?
4B. Solve 1/236
5A. Solve 3.7914/9.2
5B. What is 1,926,560 rounded to 1 sig fig?
6A. How could you write 230 with 3 sig figs?
6B. What is 0.00056798 rounded to 4 sig figs?

Today…



Turn in:

Get out Test Review to check

All missing work due NOW!
Our Plan:


Worksheet Race
Go over Test Review, then turn it in



Unit 2 Test
Complete Stop the Process Part 1 – Due Monday

Wrap Up: 3 things you learned in stop the process
Homework (Write in Planner):
Stop the Process Part 1

Wrap Up

As a group, come up with 3 things you learned or 1 question that you have after doing the stop the process.