Transcript File

Basic Principles of Science
What is Science?
Accuracy and Precision
Units of Measurement
Scientific Notation
Significant Figures
What is Science?
The effort to understand how the physical world works.
SCIENCE
NOT SCIENCE

Astronomy

Astrology

Physics

Magic

Neurology

Palm Reading

Chemistry

Alchemy

Evolution

Creationism
Science can only be applied to natural events. It cannot be used
to support or disprove opinions, beliefs or the truly supernatural.
Because of this, science makes no comment on philosophy,
religion, and morality.
What are Chemistry and Physics?
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Chemistry is the study of the composition of
matter and the changes that matter undergoes.
Physics is the study of the natural world, matter
and energy and how the are related.
These two fields are closely related.
Accuracy and Precision
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In science, measurements are vital for the
advancement of knowledge. Because of this,
numbers involved in raw or statistical data must
be accurate and precise.
Accuracy is a measure of how close a
measurement comes to the actual or true value
of whatever is measured.
Precision is a measure of how close a series of
measurements are to one another.
Question 1
How accurate and/or precise was the dart thrower?
A. Accurate and Precise
B. Inaccurate and Precise
C. Accurate and Imprecise
D. Inaccurate and Imprecise
Answer
How accurate and/or precise was the dart thrower?
A. Accurate and Precise
B. Inaccurate and Precise
C. Accurate and Imprecise
D. Inaccurate and Imprecise
Question 2
How accurate and/or precise was the dart thrower?
A. Accurate and Precise
B. Inaccurate and Precise
C. Accurate and Imprecise
D. Inaccurate and Imprecise
Answer
How accurate and/or precise was the dart thrower?
A. Accurate and Precise
B. Inaccurate and Precise
C. Accurate and Imprecise
D. Inaccurate and Imprecise
Units of Measurement
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In science, measurements are made in an
improved version of the metric system; the
International System of Units (or SI Units) used
and understood by scientists worldwide.
SI BASE UNITS
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Length
(meters “m”)
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Mass
(kilogram “kg”)
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Time
(seconds “s”)
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Temperature
(Kelvin “K”)
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Amount of Substance
(moles “mol”)
SI Units
Conversion Scales
SI Units use a scale of 10 to change between prefixes
Question 3
Convert the following measurements.
Sample A. 3,201 km
to
_____ m
Sample B. 133.8 ms
to
_____ s
1. 671 mL
to
_____ L
2. 14 cm
to
_____ µm
3. 5.08 m
to
_____ nm
4. 1.2 kW
to
_____ mW
5. 19,055 kJ
to
_____ MJ
Question 3
Convert the following measurements.
Sample A. 3,201 km
to
3,201,000 m
Sample B. 133.8 ms
to
0.1338 s
1. 671 mL
to
_____ L
2. 14 cm
to
_____ µm
3. 5.08 m
to
_____ nm
4. 1.2 kW
to
_____ mW
5. 19,055 kJ
to
_____ MJ
Answers
Convert the following measurements.
Sample A. 3,201 km
to
3,201,000 m
Sample B. 133.8 ms
to
0.1338 s
1. 671 mL
to
0.671 L
2. 14 cm
to
140,000 µm
3. 5.08 m
to
5,080,000,000 nm
4. 1.2 kW
to
1,200,000 mW
5. 19,055 kJ
to
19.055 MJ
Scientific Notation
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In science (and particularly chemistry) you
encounter very large or very small numbers.
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Examples:
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1 gram of Hydrogen contains approximately
602,000,000,000,000,000,000,000 atoms
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A single atom of Gold has an approximate mass of
0.000 000 000 000 000 000 000 327 gram
For this reason, a shorthand system for writing
sizable numbers is used.
Scientific Notation is an expression of numbers
in the form m × 10n where m is between 1 and
10, and n is an integer.
Scientific Notation

To convert numbers into scientific notation,
move the decimal until there is only one nonzero number in front of it. The number of moves
is equal to the exponent.
Question 4
Change these numbers to scientific notation.
Sample A. 3,071,000
to
________
Sample B. 0.0014
to
________
1. 6500
to
________
2. 0.000 2
to
________
3. -137.7
to
________
4. 1,200,009
to
________
5. 0.000 636
to
________
Question 4
Change these numbers to scientific notation.
Sample A. 3,071,000
to
3.071 x 106
Sample B. 0.0014
to
1.4 x 10-3
1. 6500
to
________
2. 0.000 2
to
________
3. -137.7
to
________
4. 1,200,009
to
________
5. 0.000 636
to
________
Answers
Change these numbers to scientific notation.
Sample A. 3,071,000
to
3.071 x 106
Sample B. 0.0014
to
1.4 x 10-3
1. 6500
to
6.5 x 103
2. 0.000 2
to
2 x 10-4
3. -137.7
to
-1.377 x 102
4. 1,200,009
to
1.200 009 x 106
5. 0.000 636
to
6.36 x 10-4
Significant Figures
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When measuring, the exactness of your
measurements are very important. To
determine which figures are important, we use
the five rules of significant figures.
All the digits that can be known precisely in a
measurement are significant figures.
Significant figures must be determined before
converting numbers into scientific notation.
Rules of Significant Figures
1. All non-zero numbers (1-9) ARE significant.
2. All zeros between non-zeros ARE significant.
Example: 1001 has four significant figures.
3. Leftmost zeros in front of non-zeros ARE NOT.
Example: 0.000032 has two significant figures.
Rules of Significant Figures
4. Zeros at the end of a number and to the right of
a decimal point ARE significant.
Example: 450.0 and 1.020 have four significant
figures.
NOTE – the number MUST have a decimal point
5. Zeros at the rightmost end of a number and are
left of an 'understood decimal point' ARE NOT.
Example: 1 000 and 60 000 have one significant
figure.
PLEASE NOTE THE DIFFERENCE
Question 5
How many significant figures are in these numbers?
Sample A. 3002.0
has ________
Sample B. 0.00 670
has ________
1. 223
has ________
2. 1 000 000.0
has ________
3. 0.05070
has ________
4. 300.
has ________
5. 0.0 074 010
has ________
Question 5
How many significant figures are in these numbers?
Sample A. 3002.0
has
five
Sample B. 0.00 670
has
three
1. 223
has ________
2. 1 000 000.0
has ________
3. 0.05070
has ________
4. 300.
has ________
5. 0.0 074 010
has ________
Answers
How many significant figures are in these numbers?
Sample A. 3002.0
has
five
Sample B. 0.00 670
has
three
1. 223
has
three
2. 1 000 000.0
has
eight
3. 0.05070
has
four
4. 300.
has
three
5. 0.0 074 010
has
five
Multiplying in Scientific Notation
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When multiplying numbers in scientific notation,
the first two integers multiplied as normal.
The exponents are added NOT MULTIPLIED.
If the number at the front becomes larger than
10, move the decimal to the left and add one to
the exponent.
The significant figures of your answer may not
be greater than the SMALLEST number of
significant figures in the factors.
Example
(2.1 x 103) x (5.2 x 105)
Multiplying in Scientific Notation
(2.1 x 103) x (5.2 x 105)
multiply the first numbers
2.1 x 5.2 = 10.92
adjust for significant figures
10.92 ~ 11
add the exponents
3+5=8
put together
11 x 108
adjust the first number
1.1 x 109
Dividing in Scientific Notation
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When Dividing numbers in scientific notation,
the first two integers divided as normal.
The exponents are subtracted NOT DIVIDED.
If the number at the front becomes smaller than
1, move the decimal to the right and subtract
one from the exponent.
The significant figures of your answer may not
be greater than the SMALLEST number of
significant figures in the quotients.
Example
(3.5 x 106) / (5.6 x 102)
Dividing in Scientific Notation
(3.5 x 106) / (5.6 x 102)
divide the first numbers
3.5 / 5.6 = 0.625
adjust for significant figures
0.625 ~ .63
subtract the exponents
6–2=4
put together
.63 x 104
adjust the first number
6.3 x 103
CLASSWORK
Calculate the answers to these problems
1)
(4 x 106) / (2 x 102)
2)
(1.5 x 102) x (4 x 107)
3)
(3.7 x 10-3) / (-1.9 x 10-8)
4)
(4.71 x 10-3) x ( 5.89 x 103)