Ch. 2.2-3 Measurement, Uncertainty, & Units

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

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

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 = 0.000000000000000000000327g one atom of Au = 3.27 x 10-22g (-) indicates smaller numbers

WB Check: Write in scientific notation: 0.000673 6.73 x 10-4 237,000,000 2.73 x 108

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

POINT > Distinguish between accuracy and precision High Low Precision

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

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: 0.000504 = 3 sf Zeros at the end, after a decimal are sig: 0.0900 = 3 sf Zeros at end of number, left of decimal maybe significant 45,000 = 2 sf 45,000. = 5sf

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

POINT > Define and calculate Significant Figures Note: Counted numbers or conversions have infinite sig figs Ex. 10 eggs x 4.332 g/egg = 43.32g Ex. 75.669m x 100cm/m = 7566.9cm

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

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

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