1. Measuring in Science Metric System Dimensional Analysis Density Scientific Notation Sig Figs

2. Scientific Notation
Numbers in science are often very large or very small.
To avoid confusion, we use scientific notation.
Scientific notation utilizes the numeric digits in a measurement followed by a power of ten.
The numeric digits are expressed as a number between 1 and 10.

3. Multiplying/Dividing with Sci Notation
When multiplying with sci notation, multiply the base numbers and ADD exponents
When dividing with sci notation, divide the base numbers and SUBTRACT the exponents

4. • There are 26,800,000 helium atoms in 1. 00 L of helium gas
• There are 26,800,000 helium atoms in 1.00 L of helium gas. Express the number in scientific notation.
26, 800,000 X 107
X 107
2.68 X 107
None of the above

5. 0.0089. Express the number in scientific notation.
None of the above

6. Conversion Factors
A conversion factor takes the unit equation and converts it into a ratio.
For example, 2.2 cm= 1 inch, so…
To convert 3 cm to inches, simply set up as follows:
3 cm in
2.2 cm

7. Dimensional Analysis (cont)
To convert 3 inches to cm, simply set up as follows:
3 in cm
1 inch

8. If there are 2 googles in 4 blats, 1 google equals _________ blats
2.0
0.1

9. M a s s
The mass of an object is a measure of the amount of matter it posses.
Mass is measured with a balance and is not affected by gravity.
Weight is the force exerted by gravity on an object
Mass and weight are not interchangeable
The SI unit for mass is the kilogram (kg)
1 kg = 2.20 lb

10. Volume Volume is the amount of space occupied by matter.
The SI unit for volume is the cubic meter (m3)
The metric unit (and the more often used unit) is the liter (L)
There are several instruments for measuring volume
1 mL = 1 cm3

11. 12.3 mL = _________cm3
12.3
0.0

12. Metric Conversions
Kilo
Hecto
Deka
M or L or g
Deci
centi
milli

13. 3.50 mg =______g
.00350
0.0

14. Sig Figs
Zeros found at the beginning of a number ARE never significant.
Therefore, 0.5 cm, 0.05 cm, and cm all have one significant digit.
Zeros found at the end of a number with no decimal point ARE NOT significant.
Therefore, 50 cm, 500 cm, and 5000 cm all have one significant digit.
All other zeros are significant
Therefore, 50.0 cm, cm, and 501cm all have three significant digits.

15. How many sig figs are in ? 3 0.

16. Finding Density for a Regular Object1.
Use the balance to find the mass of the object. Record this value on the "Density Data Chart." 2.
Use the metric ruler to measure the length, width, height, or diameter of the object. Record the values that apply to your object. 3.
Compute the volume of the object using the values determined in step 2. Record the volume on the data chart. 4.
Compute the density of the object by dividing the mass value by the volume value. Record the density on the data chart.

17. If the volume of an object is 4 mL, and the mass is 2 g, what is the density of the object? (don’t worry about units) .5
0.1

18. Finding Density for an Irregular Object1.
Use the balance to find the mass of the object. Record the value on the "Density Data Chart." 2.
Pour water into a graduated cylinder up to an easily-read value, such as 50 milliliters and record the number. 3.
Drop the object into the cylinder and record the new value in millimeters. 4.
The difference between the two numbers is the object's volume. Remember that 1 milliliter is equal to 1 cubic centimeter. Record the volume on the data chart. 5.
Compute the density of the object by dividing the mass value by the volume value. Record the density on the data chart.