1. Chapter 1 Elements and Measurements
Students are responsible for all sections in this chapter
Dang

2. Some Chemical Properties of the Elements
Matter: Describes anything with a physical presence—anything you can touch, taste, or smell.
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.
Dang

3. 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
Dang

4. 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 is common to use scientific notation.

5. Derived units
SI units of measurements comprised of a combination of the seven base units
Dang

6. Writing scientific notation
To write large or small numbers
Dang

7. Measuring Mass Mass: Amount of matter in an object.
Weight: Measures the force with which gravity pulls on an object.
Dang

8. Measuring Temperature
Dang
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

9. 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.
Dang

10. A Measurement
the unit tells you what standard you are comparing your object to
the number tells you
what multiple of the standard the object measures
the uncertainty in the measurement
scientific measurements are reported so that every digit written is certain, except the last one which is estimated
If the length is reported as 3.26 cm,
the digits 3 and 2 are certain (known).
the final digit, 6, is estimated (uncertain).
all three digits (2, 7, and 6) are significant, including the estimated digit.

11. Known & Estimated Digits
For the following volume readings, what would be measured values?
________
________
E.g
l l l l l cm
What is the length of the line?
1) cm
2) cm
3) cm

12. Accuracy, Precision, and Significant Figures1 2 4 3 cm
What is the length (units) of the black rectangle above?
Dang

13. Uncertainty in Measured Numbers
accuracy is an indication of how close a measurement comes to the actual value of the quantity
precision is an indication of how reproducible a measurement is

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.

15. Examples
Classify each of the following as (1) exact or (2) measured numbers. A.__Gold melts at 1064 °C. B.__1 yard = 3 feet C.__The diameter of a red blood cell is 6 x 10-4 cm. D.__There are 6 hats on the shelf. E.__A can of soda contains 355 mL of soda.

16. 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
Dang

17. 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.
Dang

18. 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
Dang

19. 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
Dang

20. 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
Dang

21. 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
Dang

22. Example:
Convert 1.76 yards to centimeters How many ounces are in 1.0 kg? How many in3 in 1.5 m3
Dang

23. 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 45.0 miles?
Dang

24. Derived Units: Density and Its Measurement
Density is temperature dependent.
Solids: cm3
Liquids: mL
Gases: L
Density =
Volume
Mass
Typical volume units

25. Density Ratio of mass:volume is an intensive property
value independent of the quantity of matter
Solids = g/cm3
1 cm3 = 1 mL
Liquids = g/mL
Gases = g/L
Volume of a solid can be determined by water displacement – Archimedes Principle
Density : solids > liquids >>> gases
except ice is less dense than liquid water!
For equal volumes, denser object has larger mass
For equal masses, denser object has smaller volume
Heating an object generally causes it to expand, therefore the density changes with temperature

26. Density Density compares the mass of an object to its volume.
is the mass of a substance divided by its volume.
Density Expression
Density = mass = g or g = g/cm3
volume mL cm3
Note: 1 mL = 1 cm3
Can we use density as a conversion factor to calculate mass or volume?

27. 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?
Dang