1. You are responsible for all sections in this chapter
Elements and Measurements
You are responsible for all sections in this chapter
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2. Chemistry and the Elements
Elements like #114, Uuq or ununquadium, have placeholder chemical symbols and names. These elements have yet to be officially named.
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3. Periods: 7 horizontal rows. Groups: 18 vertical columns.
International standard: 1-18
US system: 1A-8A, 1B-8B
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4. Elements and the Periodic Table
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5. Some Chemical Properties of the Elements
Physical Properties: Characteristics that do not involve a change in a sample’s chemical makeup.
Chemical Properties: Characteristics that do involve a change in a sample’s chemical makeup.
Chemical properties and chemical changes are synonymous.
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6. The Metric System (SI)
The metric system or SI (international system) is
a decimal system based on 10.
used in most of the world.
used everywhere by scientists.
All other units are derived from these fundamental units
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7. Derived units
SI units of measurements comprised of a combination of the seven base units
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8. Derived Units: Density and Its Measurement
Density is temperature dependent.
Solids: cm3
Liquids: mL
Gases: L
Density =
Volume
Mass
Typical volume units
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9. For numbers greater than or equal to 1000 and less than or equal to 0
For numbers greater than or equal to 1000 and less than or equal to it’s common to use scientific notation.
For numbers greater than or equal to 1000 and less than or equal to it’s common to use scientific notation.
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10. Scientific Notation Scientific Notation
is used to write very large or very small numbers.
for the width of a human hair of m is written 8 x 10-6 m.
of a large number such as s is written 4.5 x 106 s.
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11. Writing scientific notation
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12. Measuring Mass
Matter: Describes anything with a physical presence—anything you can touch, taste, or smell.
Mass: Amount of matter in an object.
Weight: Measures the force with which gravity pulls on an object.
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13. Measuring Temperature
TF = 1.8 TC + 32
TC = (TF – 32)
1.8
One degree Fahreheit is 100/180 = 5/9 the size of a degree Celsius or a kelvin.
K = °C
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14. Accuracy, Precision, and Significant Figures
Significant figures: The number of meaningful digits in a measured or calculated quantity. They come from uncertainty in any measurement.
Generally the last digit in a reported measurement is uncertain (estimated).
Exact numbers and relationships (7 days in a week, 30 students in a class, etc.) effectively have an infinite number of significant figures.
E.g cm
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15. Accuracy, Precision, and Significant Figures in Measurement
Mass of a Tennis Ball
(True mass = g)
The data vary only in the fourth decimal place.
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16. Accuracy, Precision, and Significant Figures1 2 4 3 cm
What is the length (units) of the black rectangle above?
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17. Accuracy, Precision, and Significant Figures
Rules for counting significant figures (left-to-right):
Zeros in the middle of a number are like any other digit; they are always significant.
4.803 cm 4 sf
2. Zero at the beginning of a number are not significant (placeholders).
g sf or 6.61 x 10-3 g
3. Zeros at the end of a number and after the decimal point are always significant.
K sf
4. Zeros at the end of a number and after the decimal point may or may not be significant.
34, ? SF
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18. Rounding Numbers
If the first digit you remove is less than 5, round down by dropping it and all following numbers. =
If the first digit you remove is 6 or greater, round up by adding 1 to the digit on the left.
= 5.666
3. If the first digit you remove is 5 and there are more nonzero digits following, round up.
= 5.665
4. If the digit you remove is a 5 with nothing following, round down. =
Books sometimes use different rules for this one.
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19. Multiplication and Division
When multiplying or dividing
the final answer must have the same number of significant figures as the measurement with the fewest significant figures.
Example:
x = = (rounded)
4 SF SF calculator SF
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20. Addition and Subtraction
When adding or subtracting
the final answer must have the same number of decimal places as the measurement with the fewest decimal places.
one decimal place
two decimal places
calculated answer
final answer with one decimal place
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21. Calculations: Converting from One Unit to Another
Dimensional analysis: A method that uses a conversion factor to convert a quantity expressed in one unit to an equivalent quantity in a different unit.
Conversion factor: States the relationship between two different units.
original quantity x conversion factor = equivalent quantity
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22. Conversion Factors A conversion factor is obtained from an equality.
Equality: 1 in. = 2.54 cm
written as a fraction (ratio) with a numerator and denominator.
inverted to give two conversion factors for every equality.
1 in and cm
2.54 cm in.
may be obtained from information in a word problem and is written for that problem only.
Example :
The cost of one gallon (1 gal) of gas is $4.29.
1 gallon of gas and $4.29
$ gallon of gas
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23. Example:
Convert 1.76 yards to centimeters How many ounces are in 1.0 kg? How many in3 in 1.5 m3
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24. Examples
If your pace on a treadmill is 65.0 meters per minute, how many minutes will it take for you to walk a distance of 7500 feet?
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25. Examples
Osmium is a very dense metal. What is its density in g/cm3 if 0.11 lb of osmium has a volume of 2.22 ml?
The density of octane, a component of gasoline, is g/mL. What is the mass, in kg, of 875 mL of octane?
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