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CH 2
MEASUREMENTS
DIRECTIONS:
READ Ch 2.1 (p. 11) & 2.3 (pg. 14-16)
Answer Questions #4-5 (notes side)
TN Ch 2.3 Date
Title and
Highlight
Topic:
EQ:
Questions:
Write Question out and answer it (in
another color or skip a space) based on
from what you read.
NOTES:
Now write out the notes from my
website. You may use different color
pens.
Number notes as you go.
Space out your notes so you can add
anything I say to them.
BUT NO HIGHLIGTING,
UNDERLINING, etc
WE WILL DO OUR FOCUS NOTES
TOGETHER
Right Side – NOTES ONLY
TN Ch 2.3
Title and
Highlight
DRAW ANY PICTURES, FIGURES,
AND WRITE OUT ANY PRACTICE
PROBLEMS/QUESTIONS.
WE WILL ANSWER THEM TOGETHER.
LEAVE SPACES SO WE CAN ANSWER
QUES.
LEFT Side – PICTURES, PRACTICE PROBLEMS, ETC
TN CH 2.1, 2.3 TOPIC: SIGNIFICANT FIGURES
EQ: HOW DO YOU DETERMINE IF A NUMBER
IS SIGNIFICANT?
2.1 MEASURING ITEMS A UNIT is a standard, agreed-on quantity
by which other quantities are measured.
The uncertainty is indicated by the last
reported digit.
Example: 42.56 grams
Scientific numbers are reported so that
every digit is certain except the last,
which is estimated.
CH 2.3 WRITING NUMBERS TO
REFLECT PRECISION
SIGNIFICANT FIGURES: SIG FIG’S (S.F.)
The greater the precision of the measurement,
the greater the number of significant figures!!!
Determining s.f.’s are fairly easy to
determine.
HOWEVER…if the number contains
a ZERO then we must determine if it
is significant!
RULES FOR COUNTING SIGNIFICANT
FIGURES
Rule #1 - Nonzero integers always count
as significant figures.
3456 has 4 sig figs.
Rule #2 - Leading zeros do not count as
significant figures.
0.0486 has 3 sig figs.
These ZERO’s are called PLACEHOLDERS!
Rule #3 - Captive zeros always count as
significant figures.
16.07 has 4 sig figs.
Rule #4 - Trailing zeros are significant
only if the number contains a decimal
point.
9.300 has 4 sig figs.
PRACTICE #1 (LEFT SIDE)
How many significant figures in each of the following?
1.0070 m
17.10 kg
100,890 L
3.29 x 103 s
0.0054 cm
3,200,000
How many significant figures are in each
number?
0.0035
1.080
2371
2.97×105
1 dozen
100.00
100,000
Practice #2 (left side)
Determine the number of
significant digits in the
following numbers:
2.3000x106
45.1
800000.103
.000000001500
600
500.
Practice #3 (left side)
Ch 2.4
Topic: PERFORMING
CALCULATIONS
USING SIG FIG’S
EQ: How do we
determine how many
Sig Fig’s an answer in
a calculation would
have?
DIRECTIONS:
READ Ch 2.4 (pg. 17 - 21)
Answer Questions #7-10 (notes side)
TN Ch 2.4 Date
Title and
Highlight
Topic:
EQ:
Questions:
Write Question #7-10 out and answer it
(in another color or skip a space) based
on from what you read.
NOTES:
Now write out the notes from my
website. You may use different color
pens.
Number notes as you go.
Space out your notes so you can add
anything I say to them.
BUT NO HIGHLIGTING,
UNDERLINING, etc
WE WILL DO OUR FOCUS NOTES
TOGETHER
Right Side – NOTES ONLY
TN Ch 2.4
Title and
Highlight
DRAW ANY PICTURES AND WRITE
OUT ANY PRACTICE
PROBLEMS/QUESTIONS.
WE WILL ANSWER THEM TOGETHER.
LEAVE SPACES SO WE CAN ANSWER
QUES.
LEFT Side – PICTURES, PRACTICE PROBLEMS, ETC
RULES FOR ADDING/SUBTRACTING SIG
FIGS
Addition and Subtraction: least places
after the decimal between all the numbers
you are adding or subtracting.
LET’S PRACTICE….(LEFT SIDE)
0.987 + 125.1 + 1.22 = ??
5.98 – 3.449 – 0.765 = ??
2.18 + 5.621 + 1.5870 + 2 = ??
7.876 – 12.56 + 123.792 = ??
Multiplication and Division: least # of
sig figs between ALL numbers.
RULES FOR MULTIPLYING/DIVIDING
SIG FIGS
LET’S PRACTICE….(LEFT SIDE)
1.01 x 0.12 x 53.51 = ??
56.55 ÷ 0.920 = ??
1.10 x 0.512 ÷ 1.5870 = ??
4.562 x 3.99870 ÷ 89.5 = ??
SIG FIG’S IN CALCULATIONS
RULES FOR ROUNDING: • For calculations involving multiple steps,
round only the final answer— do not round
off between steps.
This prevents errors in the final answer.
Don’t round if the last digit dropped is 4 or less
Round up if the last digit dropped is 5 or more.
• Example: If you need only 3 s.f.’s, then
35.44 is 35.4 (don’t round up)
35.45 is 35.5 (round up)
CALCULATIONS INVOLVING BOTH
MULTIPLICATION/DIVISION AND ADDITION/SUBTRACTION
1. Do parentheses first.
2. Determine the correct # of sig figs in the
answer without rounding.
3. Then do the remaining steps.
4. Remember order of opp’s: P.M.D.A.S.
5. ONLY look at final answer when
determining to round
LET’S PRACTICE….(LEFT SIDE)
3.489 x (5.67 – 2.3) = ??
6.78 x 5.903 x (5.489 + 5.01) = ??
19.667 ÷ (5.4 x 0.916) = ??
CH 2.5
TOPIC: BASIC UNITS OF
MEASUREMENT
EQ: WHAT ARE THE DIFFERENT
TYPE OF UNITS USED?
DIRECTIONS:
READ Ch 2.5 (pg. 22-24)
Answer Questions #11, 12, 14 (notes side)
TN Ch 2.5 Date
Title and
Highlight
Topic:
EQ:
Questions:
Write Question #11, 12, 14 out and
answer it (in another color or skip a
space) based on from what you read.
NOTES:
Now write out the notes from my
website. You may use different color
pens.
Number notes as you go.
Space out your notes so you can add
anything I say to them.
BUT NO HIGHLIGTING,
UNDERLINING, etc
WE WILL DO OUR FOCUS NOTES
TOGETHER
Right Side – NOTES ONLY
TN Ch 2.5
Title and
Highlight
DRAW ANY PICTURES AND WRITE
OUT ANY PRACTICE
PROBLEMS/QUESTIONS.
WE WILL ANSWER THEM TOGETHER.
LEAVE SPACES SO WE CAN ANSWER
QUES.
LEFT Side – PICTURES, PRACTICE PROBLEMS, ETC
2 types of measuring systems:
1. English system (USA):
Ex: inches, yards, pounds.
2. Metric system (most of the world):
Ex: grams, meters, Liters
Every measurement must have a unit.
HIGHLIGHT PROBLEM (READ ONLY)
In 1999, NASA lost a $94
million orbiter because
two groups of engineers
failed to communicate to
each other the units that
they used in their
calculations.
Consequently, the
orbiter descended too far
into the Martian
atmosphere and burned
up.
In 1795, scientist around the world came
together to develop a unit system for science
measurements, based on the metric system.
• Called the International System of units
or SI units.
MASS VS. WEIGHT
Mass depends on the amount of
___________ in the object.
Weight depends on the force of
____________ acting on the object.
______________ may change as
you move from one location to
another; ____________ will not.
You have the same ____________
on the moon as on the earth, but
you ___________ less since there
is less _________ on the moon.
Draw pic (left side)
matter
gravity
Weight
mass
mass
gravity
weigh
Mass = 80 kg
Weight = 176 lbs.
Mass = 80 kg
Weight = 29 lbs.
PREFIX MULTIPLIERS (LEFT SIDE)
METRIC SYSTEM
Base
Units
kilo hecto deca
meter
liter
gram
Seconds
deci centi milli
An easy way to move the decimal point one place for each “step” desired
Use Prefixes!!!
Prefixes
Prefixes
METRIC SYSTEM
400,000 centimeters =________kilometers
kilo hecto deca
meter
liter
Gram
Seconds
deci centi milli
METRIC SYSTEM
5000 meters = _____ millimeters
If you move to the right in the diagram, move the decimal to the right
kilo hecto deca
meter
liter
gram
deci centi milli
kilo hecto deca
meter
liter
gram
deci centi milli
6700 centimeters = ___ meters
If you move to the left in the diagram, move the decimal to the left
Mount Everest is 8847 m high. How many
centimeters & kilometers high is the
mountain?
Practice #1: (left side)
380 km = ______________m
1.45 mm = _________m
461 mL = ____________dL
0.4 cg = ____________ dag
0.26 g =_____________ mg
230,000 m = _______km
CH 2.6 & 2.9
TOPIC: DENSITY
EQ: HOW CAN YOU
DETERMINE AN
OBJECT’S DENSITY?
DIRECTIONS:
READ Ch 2.6 & 2.9 (pg. 25, 27, 28, 34, 35)
Answer Questions #17, 18, 29, 30 (notes side)
TN Ch 2.6 & 2.9 Date
Title and
Highlight
Topic:
EQ:
Questions:
Write Question # 17, 18, 29, 30 out and
answer it (in another color or skip a
space) based on from what you read.
NOTES:
Now write out the notes from my
website. You may use different color
pens.
Number notes as you go.
Space out your notes so you can add
anything I say to them.
BUT NO HIGHLIGTING,
UNDERLINING, etc
WE WILL DO OUR FOCUS NOTES
TOGETHER
Right Side – NOTES ONLY
TN Ch 2.6 & 2.9
Title and
Highlight
DRAW ANY PICTURES AND WRITE
OUT ANY PRACTICE
PROBLEMS/QUESTIONS.
WE WILL ANSWER THEM TOGETHER.
LEAVE SPACES SO WE CAN ANSWER
QUES.
LEFT Side – PICTURES, PRACTICE PROBLEMS, ETC
Not all quantities can be measured
with base units.
A unit that is defined by a
combination of units is called a
derived unit.
Two derived units are volume and
density.
VOLUME
Volume is the space occupied by an object.
The derived unit for volume is the cubic centimeter (cm3); used for solid objects.
Liter (L) are used to measure the amount
of liquids. For the smaller quantities, volume is
measured in milliliters (mL).
1 mL = 1cm3 ( this is how we can go from units of a
solid to a liquid)
DENSITY
Density is a ratio that compares the mass
of an object to its volume
The units for density:
grams per cubic centimeter (g/cm3) for
solids
grams per milliliter (g/mL) for liquids
DENSITY
The density of an object will determine if it will
float or sink in another phase. If an object floats, it
is _______ dense than the other substance. If it
sinks, it is ________ dense.
The density of water is 1.0 g/mL
m
D V X Mass = D x V
less
more
Volume = m/D
Density = m/V
KNOW VS FIND CHART:
HOW TO SHOW YOUR WORK
Sort: Begin by sorting the information in the problem. (Know vs. Find)
Units: Do not let units magically appear or disappear in calculations. Units must flow logically from beginning to end.
Solve: Carry out calculation (pay attention to sig. fig. rules and cancel units as needed.
Remember order of opp’s: P.M.D.A.S.
Know ?? m = 44.7g Density V = 15.98mL
What is the volume of chemical sample that
has a mass of 24 g and a density of 6 g/mL?
Practice #1: (left side)
What is the density of 52g of Fe (iron) and
that occupies 31.5 cm3 of volume?
Will this float or sink in water?
Practice #2:
Densities are sometimes determined by “water displacement” – Lab next week!!!
An irregularly shaped piece
of metal with a mass of 125g
is placed into a graduated
cylinder that contains 7.00mL
of water. This raises the
water level to 20.50mL. What
is the density of the metal?
Practice #3:(left side)
Calculate the mass of a block of iron
(density = 7.86g/cm3) with dimensions of
52.8cm x 6.74cm x 3.73cm.
Practice #4:(left side)
DENSITY’S OF SUBSTANCES (LEFT SIDE)
Table 2.4 provides a list
of the densities of some
common substances.
This is useful when
solving homework
problems.
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