1. Scientific Measurement Ch. 3
Why are precise measurements and calculations essential to the study of chemistry?

2. (3.1) Measurements
Quantity that has a number and unit

3. Accuracy and Precision
How close a measurement comes to the actual value of what is being measured
How close a series of measurements are to one another

5. KNOW the rules for determining sig figs Pgs. 66-67
Significant Figures
KNOW the rules for determining sig figs Pgs

6. Measured values having digits that are known with certainty and a final digit that is estimated

7. 1) ALL non-zero numbers are ALWAYS significant.
2) ALL zeroes between non-zero numbers are ALWAYS significant.
3) ALL zeroes which are to the right of the decimal point AND at the end of the number are ALWAYS significant.
4) ALL zeroes to the left of a decimal point and in front of nonzero digits are not significant.
5)Numbers in scientific notation…count those in the coefficient only.

8. 48, ,000,

10. Sig Figs in Calculations
Many-Places Rule
Mult./Div. – how many sig figs in least
Plus/Minus – no. of places in least

11. 305.1 x ÷

12. Percent Error
Error = Experimental value - Theoretical
Percent error =

13. Scientific Notation
6.02 x 1023
(see pg. R56 of text for more practice)