1. Scientific notation is used to express very large or very small numbers in a standard way using a coefficient and power of 10. 2. Theories are explanations based on repeated experimentation and observation, while laws are rules of nature. Theories do not become laws. 3. Significant figures tell us how precisely a measurement or number is known and indicate the reliability of the last digits.

1. Warm-up Which number is the largest? a. 1.13 x 10 9 b. 3.51 x 10 3 c. 5.88 x 10 5 d. 7.92 x 10 2 Which unit can be used to measure volume? a. m b. m 2 c. m 3 Which of the following units is the longest? a. meter b. centimeter c. kilometer d. millimeter

2. 1-4 Scientific Notation Compare and contrast scientific theories, and scientific laws. Use numbers involving scientific notation. Determine significant figures.

3. Law vs. Theory Law – a rule of nature Answers the question “what?” Examples: Law of Attraction and Repulsion, Law of Gravity Theory – An explanation based on repeated experimentation and observation. Answers the question “why” Examples: Theory of Evolution, Atomic Theory

4. Law vs. Theory Theories do not become laws!!! What doesn’t replace why! A theory represents everything currently known about a topic.

5. Scientific Notation Designed for the expression of very big and very small numbers 3.6 x 10 4 1 gram of hydrogen contains 301,000,000,000,000,000,000,000 molecules 3.01 x 10 23 molecules a coefficient and a power of 10 Exponent represents number of places decimal moved. 0.00081 = 8.1 x 10 -4 Number is smaller than 1 – negative exponent 34,000 = 3.4 x 10 4 Number is greater than 1 – positive exponent

6. Sci. Not. Practice 62900 6.29 x 10 4 0.00028 2.8 x 10 -4 1720000 1.72 x 10 6 0.0753 7.53 x 10 -2

7. Significant Figures A method of expressing error in measurement. Measure a value and then estimate one digit below the smallest unit on the tool. 5.35 cm

8. Significant Figures Atlantic – Pacific Rule Pacific – "P" is for decimal point is present Count significant digits starting with the first non-zero digit from the left. 0.004703 has 4 significant digits. 18.00 also has 4 significant digits. Atlantic – "A" is for decimal point is absent . Start counting significant digits with the first non-zero digit from the right. 140,000 has 2 significant digits. 20060 has 4 significant digits.

9. Examples 50.3 3 SF 0.0008 1 SF 200200 4 SF 57.00 4 SF 490 2 SF 10000000 1 SF

10. 1-4 Summary What is scientific notation? Scientific notation is used to express very large or very small numbers. What are significant figures? Significant figures tell us how important the numbers are.