1. The International System (SI)
Uses the Metric System to describe quantitative (measured) properties of matter rather than qualitative (non measured) characteristics
Metric System
Uses a set of standard base units for measuring
Conversions between base units are easily calculated
Prefixes are added to base units to obtain smaller or larger quantities
Works using powers of ten (10n)

4. Mass
Measure of the quantity of matter present against a standard
Weight
Measure of the force of gravity on an object
Example
On Earth a led ball has a wt. Of 8 kg. When taken to the moon it has a wt. of 1kg. Does the amount of matter (lead) change?
The difference in weight is due to gravity. The mass does not change

5. Temperature U.s. uses Fahrenheit (oF) degrees
SI uses Kelvin (K) in calculations but measures in Celsius (oC) degrees
K = oC + 273
oC = K – 273
oC based on properties of water
Freezes at 0oC
Boils at 100oC
HW read pgs pg.30 # 4,5 and 7-11

6. Scientific Notation Expresses numbers as multiple of two factors
One whole number to left of a decimal point
Ten raised to a power or exponent
Exponent tells how many times the number is multiplied by 10

7. Adding and subtracting scientific notation
Make powers the same exponent
Add or subtract numbers
Retain the power of 10 (exponent)

8. Multiplying and Dividing using Scientific Notation
Multiply or divide the numbers
If multiplying: add exponents
If dividing: subtract exponents
Readjust for proper notation
HW read pgs pg.32 #12-14 pg.33 #15-16

9. Accuracy and Precision
How close a measurement is to the true or actual(correct,targeted) value for the quantity
Being exact
Precision
How close a set of measurements for a quantity are to one another, regardless of whether the measurements are correct
Allowable tolerance or deviation

10. Examples Measure boiling water three times with same thermometer
The following measurements are recorded
97oC, 97oC, 97oC
Since the data are not 100oC the measurements are not accurate, but they are consistent and close so they are precise
A different thermometer records
100oC, 100oC, 100oC
Since the measured values are all correct, the measurements are accurate
Note: accurate measurements are also precise

11. Percent Error
Shows the deviation of collected experimental(exp) data(measurements) to a given or true value
Percent error = experimental value – accepted value x 100
accepted value
Negative value shows too little
Positive value shows too much
Actual error = exp. – true
HW Read pgs pg.38 #29-30

12. Significant figures
All digits that occupy places for which an actual measurement was made
Used in calculations
In multiplication and division the result must be reported with the same number of sig figs as the measurement with the fewest sig figs
In addition and subtraction the result cannot have more digits to the right of the decimal point than any of the original numbers
HW Read pgs do worksheets