Week 19 Chemistry
Significant Figures, Scientific Notation, Dimensional Analysis
Warm Up: 4 Minutes
Sit anywhere you’d like
No more than 4 people per row
Draw the Lewis Dot Structure for PH3.
What is the molecular structure for PH3?
Write the Learning
Target
Class Dojo(starting TODAY)


If you are being disrespectful in class

Talking out of turn

Not participating

Out of your seat without permission (once the bell rings, where should you be???)

Arguing with the teacher

Etc.
Each behavior miscue will be tracked
You will hear a sound for each
behavior!
Class Dojo(starting TODAY)


But you also get points for being good!
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Taking Notes

Following directions

Being on task

Helping another student during IP
Each good behavior will also be tracked
You will hear a sound for each
behavior!
Agenda

Warm Up- 7 Minutes

Cornell Style Notes & Examples- 12 Minutes

Guided Practice- 12 Minutes

Independent Practice- 18 Minutes

Closing – 4 Minutes
Goal For Today
Student Given:
34567
Student Answer:
5 significant
figures
Take out paper for notes
BLUE
RED
Let’s think about something…
Which number has more significant figures?
100.0
100.00
What is a significant figure?
Digits in a number that carry meaning
contributing to the precision
Rule #1
Non-zero digits are ALWAYS significant
Example:
243
3 significant figures
Check Point
How many significant figures are in
12469?
5 significant figures
Rule #2
Zeros between non-zero digits are ALWAYS
significant
Example:
2014
4 significant figures
Check Point
How many significant figures are in
10002?
5 significant figures
Rule #3
Leading zeros are NOT significant
Example:
0.0005
1 significant figure
Example:
0.0045
2 significant figures
Check Point
How many significant figures are in
0.000000000512?
3 significant figures
Rule #4
Zeros to the right of all non-zero digits are only
significant IF a decimal point is shown
Example:
0.003120
4 significant figures
Example:
31200
3 significant figures
Check Point
How many significant figures are in
35000?
2 significant figures
Check Point
How many significant figures are in
35000.0?
6 significant figures
Guided Practice

Teacher:
1. Will show the problem on the board

Students:
1.
Take 12 seconds to identify the number of
significant figures individually.
2.
Take 27 seconds to speak with your shoulder
partner about the number of significant figures
3.
Be ready to share when Mr. Ghosh says SWAG
#1
204.1
4 significant figures
#2
900.06
5 significant figures
#3
0.0000317010
6 significant figures
#4
8,000,000,000
1 significant figure
#5
1.00
3 significant figures
Independent Practice
85%
Silence
Closing
How many significant figures are in
3,000,000?
How many significant figures are in
3,000,000.0?
Warm Up: 4 Minutes
Sit anywhere you’d like
No more than 4 people per row
Write the Learning
Target
Write the number of significant figures in each of the
following measurements:
0.0000423 meters
2000 inches
145.6 Liters
2050607 Basketballs
Agenda

Warm Up- 7 Minutes

Cornell Style Notes & Examples- 14 Minutes

Guided Practice- 12 Minutes

Independent Practice- 16 Minutes

Closing – 4 Minutes
Goal For Today
Student Given:
12 * 13
Student Answer:
160 (why???)
Take out paper for notes
BLUE
RED
What are significant figures again???
Digits in a number that carry meaning
contributing to the precision
Rules for Using Significant Figures
Different rules apply for Addition/Subtraction and
Multiplication/Division
The Addition/Subtraction rule
When adding or subtracting, round your final answer to the
same number of decimal places as the measurement with
the LEAST number of decimal places
Example #1
17.2 + 12.54 + 16.912
Example #2
1.4 + 32.11 + 2
Example #3
213.91 – 13.24 + 64.856
The Multiplication/Division rule
When multiplying or dividing, round your final answer to the
same number of significant figures as the measurement with
the LEAST number of significant figures
Example #1
17.2 * 2.7 * 13.22
Example #2
12.42 * 1.23 * 21.3546
Example #3
143.77 ÷ 21.2
Guided Practice

Teacher:
1. Will show the problem on the board

Students:
1.
Take 42 seconds to solve the problem individually.
2.
Take 66 seconds to speak with your shoulder
partner about the answer and the process
3.
Be ready to share when Mr. Ghosh says SWAG
#1
Gloria obtained a sample of gold. She
found that it had a mass of 212.34 grams
and a volume of 11.0 mL. What was the
density of her sample of gold? Express
your answer in g/mL.
mass
Density =
volume
#2
The masses of four graduated cylinders were
measured. The first mass was 23.618 grams, the
second mass was 24.28 grams, the third mass was
22.981 grams, and the fourth mass was 23 grams.
What was the total mass of all four graduated
cylinders?
#3
Jorge was trying to calculate his test average in
chemistry. On his first test, he scored a 78. On
his second test, he scored a 91. On his third
test, he scored an 88.5. Assuming that all three
tests are equally weighted, what is his average
test grade?
Test 1 + Test 2 + Test 3
Average =
3
Independent Practice
85%
Silence
Closing
How do the rules for significant figures
in addition and multiplication differ?
Warm Up: 4 Minutes
Sit anywhere you’d like
No more than 4 people per row
Write the Learning
Target
Complete the following problems using the correct
number of significant figures:
What is 243 * 19?
What is 146.12 + 23.4?
Agenda

Warm Up- 7 Minutes

Cornell Style Notes & Examples- 15 Minutes

Guided Practice- 12 Minutes

Independent Practice- 15 Minutes

Closing – 4 Minutes
Goal For Today
Student Given:
Student Answer:
652000
6.52 x 105
5.1 x 10-6
0.0000051
Take out paper for notes
BLUE
RED
What is Scientific Notation?
Scientific Notation is a way to write really big
or really small numbers in decimal notation
Two parts:
Coefficient
3.45 x 107
Exponent
(power of 10)
Significant Figures in Scientific Notation
To find the number of significant figures, look at the
coefficient
Example:
1.422 x 1016
4 significant figures
Example:
6.3 x 10-55
2 significant figures
Why do we need it?
Writing really big or small numbers can take a
long time
Scientific Notation is a way to make writing
really big or really small numbers easier!!!
Examples of Scientific Notation
There are 7,000,000,000 people in the world
7.0 x 109 people
Wavelength of violet light is 0.0000004 meters 4.0 x 10-7 meters
There are 100,000,000,000,000 cells in the
human body
1.0 x 1012 cells
There are 1,390,000,000,000,000,000,000
Liters of water on Earth
1.39 x 1021 Liters
Key Vocabulary
Scientific Notation
Standard Notation  Numbers without exponents
Standard notation  Scientific notation
132,000,000 meters
_____ x 10

Step 1: Place a decimal
point after the first nonzero number

Step 2: Write the
coefficient of the
scientific notation by
dropping all the zeros
Don’t Forget Your Units!!!

Step 3: Count the
number of places from
the decimal point to the
end of the number (the
exponent)

Step 4: Write the
exponent above the 10.
132,000,000 meters
_____ x 10
Is the exponent positive or negative?
Counting to the right? Exponent is POSITIVE
Counting to the left? Exponent is NEGATIVE
Example #1
2,760,000,000,000 atoms
Example #2
0.00000000528 meters
Scientific notation  Standard notation

Step 1: Look at the
exponent

Step 2: Move the decimal
the correct number of
places (in the correct
direction), adding zeros in
the empty spaces

Step 3: Rewrite the number
6.12 x 105 grams
Don’t Forget Your Units!!!
Example #1
2.93 x 1014 milligrams
Example #2
4.77 x 10-8 mL
Guided Practice

Teacher:
1. Will show the problem on the board

Students:
1.
Take 27 seconds to solve the problem individually.
2.
Take 43 seconds to speak with your shoulder
partner about the answer and the process
3.
Be ready to share when Mr. Ghosh says SWAG
#1
6,240,000,000,000 Hz
#2
3.84 x 10-4 meters
#3
5.11 x 108 kg
#4
0.0000004036 meters
Independent Practice
85%
Silence
Closing
Convert 1452 yards to scientific notation
Convert 0.0000000054 mg to scientific
notation
Convert 4.2 x 10-7 L to standard notation
Warm Up: 4 Minutes
Sit anywhere you’d like
No more than 4 people per row
Write the Learning
Target
Write 4.23 x 10-9 meters in standard notation
Write 1,400,000 Hz in scientific notation
Agenda

Warm Up- 6 Minutes

Technology Setup – 10 minutes

Cornell Style Notes & Examples- 14 Minutes

Guided Practice- 13 Minutes

Independent Practice- 9 Minutes

Closing – 1 Minute
Get Ready to…
Technology Setup

Go to shschem.weebly.com

Wait for further instructions
Class Website
How will this class change?

Notes can be taken on computer using Microsoft
OneNote (you may still use paper and pencil if
you’d like)

All PowerPoint presentations will be online
I
will put them up at the end of the week
LIDS DOWN
Take out paper for notes
BLUE
RED
What is dimensional analysis?
The analysis of the relationships between different
physical quantities
Table of Metric Prefixes
Prefix
Giga-
Value
1,000,000,000
MegaKiloHectaDeka-
1,000,000
1,000
100
10
DeciCentiMilli-
0.1
0.01
0.001
MicroNano-
0.000001
0.000000001
Very Important!!!
How do we use the chart???
Look at chart for number corresponding to prefix
Examples:
Milliliter = 0.001 liters
Hectameter = 100 meters
Gigabyte = 1,000,000,000 bytes
Check Point
How are gigameters and meters related?
1,000,000,000 meters = 1 gigameter
Check Point
How are microliters and liters related?
0.000001 liters = 1 microliter
Conversion Factor
Proportion of two equal quantities used to convert
units
Example: Liters to milliliters
1 milliliter
0.001 Liter𝑠
Check Point
What is the conversion factor from
kilograms to grams?
1000 grams
1 kilogram
Check Point
What is the conversion factor from
centiliters to liters?
0.01 Liters
1 centiliter
Example #1
How many milliliters
are in 3.25 Liters?

Step 4: Cancel Units

down
 Step
Step 1:
5: Write
Multiply
thegiven
number
numbersand
on unit
top, divide
by numbers
on the
 Step
2: Identify
the
bottom unit
desired
 Step
Step 3:
6: Write
Roundconversion
using

significant
rules
factor
with figures
known unit
on bottom and desired
unit on top
Example #2
How many meters are in 123.5
kilometers?
Example #3
How many hectagrams is equal to
2506 grams?
Guided Practice

Teacher:
1. Will show the problem on the board

Students:
1.
Take 46 seconds to solve the problem individually.
2.
Take 52 seconds to speak with your shoulder
partner about the answer and the process
3.
Be ready to share when Mr. Ghosh says SWAG
#1
Arely signed up to run a marathon on Sunday.
The event organizer told her that it was a total
of 262 dekameters. How many meters is this?
#2
Roberto bought a new pool for his family. The
packaging said that the pool held a total of
2450 liters of water. How many centiliters is
this?
#3
Eric got ahead in chemistry and wanted to learn
about moles through an experiment. Mr. Ghosh
told him that he needed 2.604 millimoles of
Carbon to complete the experiment. How many
moles is this?
Independent Practice
85%
Silence
Exit Ticket – on Socrative
1.Go to m.socrative.com
2.Enter room number: 230538
3.Finish all questions
Warm Up: 4 Minutes
Sit anywhere you’d like
No more than 4 people per row
Write the Learning
Target
When making Texas BBQ brisket, the Food Network
says to use 0.5 teaspoons of kosher salt for a 4
pound brisket. How many centiteaspoons is this?
Agenda

Warm Up- 8 Minutes

??? - 25 Minutes

Technology Setup – 10 Minutes

Closing – 2 Minutes
Pop
Quiz
Material Covered on Quiz
 Lewis
Dot Structures
 VSEPR
Theory
 Significant
 Scientific
Figures
Notation
Goal

To demonstrate mastery, we are shooting for
Expectations

Students will keep eyes on own paper


Cheating will result in an automatic ZERO
Students will remain SILENT for the duration of the quiz
Check Point
What is your goal for this quiz?
Good Luck!!
Technology Setup

Go to shschem.weebly.com

Wait for further instructions
Class Website
How will this class change?

Notes can be taken on computer using Microsoft
OneNote (you may still use paper and pencil if
you’d like)

All PowerPoint presentations will be online
I
will put them up at the end of the week
Note Taking Method

Microsoft OneNote
Closing

How was your quiz?

What topics do you feel you still need review on?