1. Ch. 2.2-3 Measurement, Uncertainty, & Units

2. POINT > Describe Scientific Notation
POINT > Distinguish between accuracy and precision
POINT > Define and calculate Significant Figures
POINT > Convert SI units (worksheet)
POINT > Distinguish between mass and weight

3. POINT > Describe Scientific Notation (SN)
SN is a way of writing very large or small numbers as a product of two numbers
602,000,000,000,000,000,000,000 atoms in 1g of H
6.02 x 1023 atoms in 1g of H
(+) indicates larger numbers

4. POINT > Describe Scientific Notation (SN)
SN is a way of writing very large or small numbers as a product of two numbers
one atom of Au = g
one atom of Au = 3.27 x 10-22g
(-) indicates smaller numbers

5. WB Check:
Write in scientific notation:
6.73 x 10-4
237,000,000
2.73 x 108

6. POINT > Distinguish between accuracy and precision
How close a measurement comes to the actual value of what is measured
How close a series of measurements are to one another

7. POINT > Distinguish between accuracy and precision
High
Low
Precision

8. POINT > Define and calculate Significant Figures
Sig figs include all of the digits that are known, plus a last digit that is estimated

9. POINT > Define and calculate Significant Figures
Figure 3.3 page 45
Zeros between nonzeros are significant: 507,003 = 6 sf
Zeros in front of all nonzeros are not: = 3 sf
Zeros at the end, after a decimal are sig: = 3 sf
Zeros at end of number, left of decimal maybe significant
45,000 = 2 sf ,000. = 5sf

10. POINT > Define and calculate Significant Figures
Sample problem D (p45) and Practice 1-2 (p46)
When calculating, the given value with the least sig figs is the number of sig figs you use in the final answer
5.0 x 3.738
= 18.69
=19

11. POINT > Define and calculate Significant Figures
Note: Counted numbers or conversions have infinite sig figs Ex. 10 eggs x g/egg = 43.32g Ex m x 100cm/m = cm

12. WB Check: Determine the area of a room measuring 7. 7 m x 5. 4 m
WB Check: Determine the area of a room measuring 7.7 m x 5.4 m. Answer with correct Sig Fig. 42 m2

13. Homework:
Finish reading Chapter 2!
#2-3 page 29
#5a-b page 40
#1-9 page 55

14. Determining Significant Figures
Atlantic/Pacific Method – It’s about the decimal
Decimal Present
(Pacific)
Decimal Absent
(Atlantic)
NON-ZEROS
(and zeros between non-zeros)
Ignore zeros to
the left (Pacific) of
first non-zero
Ignore zeros to
the right (Atlantic) of
final non-zero
Everything else is significant