“Unit I: Matter and Scientific Calculations”

1. “Unit I: Matter and Scientific Calculations” Chemistry I Honors

2. Objectives #1-6: Matter – Properties and Changes *The material in Objectives # 1-3 should have been mastered in previous coursework. Laboratory exercises will be performed to review the material. *You should be able to answer the questions listed in your homework packet; Ask for additional assistance if needed; these types of questions will appear on the unit test. *Worksheets #1, p.11, Activity 1-3

3. Objectives #1-6: Matter – Properties and Changes *Review the list of elements/symbols and polyatomic ion names/formulas *You should be familiar with your list of symbols and names for the Unit 1 Test. *The list of polyatomic ions should be memorized before we begin Unit 5.

4. Notes from Lab: Please don’t forget to record any notes from the Water Filtration Lab that you may wish to review as you prep for this unit test.

5. Classification of Matter

6. Classification of Matter Matter - has mass and volume Pure Substances - one type of matter, definite composition Mixtures - more than one type of matter, no definite composition Elements - can’t be broken down chemically Compounds - can be chemically broken down Homogeneous Mixtures (solutions) - can be physically separated, uniform Heterogeneous Mixtures - can be physically separated and not uniform

7. Sections of the Periodic Table

8. The Periodic Table…

9. Types & Basic Characteristics of Elements Groups: 1-18; Run vertically; similar chemical properties due to electron configurations Periods: 1-7; Run horizontally; same number of energy levels to hold electrons of elements Metals: Groups 1-16 (under the stairstep line) • Luster • Conducts electricity • Malleable • Ductile • High melting point • Generally solids at room temperature

10. Types & Basic Characteristics of Elements Nonmetals:Groups 13-18 (above the stairstep line) • Dull • Insulator • Brittle • Low melting point • Exist as solids, liquids & gases at room temperature

11. Types & Basic Characteristics of Elements Metalloids: Along the stairstep line, except Aluminum (#13) & Polonium (#84) • Have a somewhat metallic luster • Semi-conductor • Less malleable than metals, but not brittle • Intermediate melting points • Solids at room temp

12. Objectives #7-13:Basic Math Skills *You should be able to solve the text problems listed below; please come in for help immediately if you need assistance;these types of problems will appear on quizzes and the unit test P.40 # 1-3 P. 59 # 7, 16, 19 P.42 # 1,2,3,5 P. 60 # 43, 44 P. 57 # 7, 8

13. Objectives #14-16Using Scientific Measurements *All measurements contain some error; the quality of measurements can be determined by determining their: • Accuracy-closeness of a measurement to the true value • Precision- consistency of repeated measurements *Accuracy can be measured by calculating the percent error Observed Value – Actual Value x 100 Actual Value

14. *example: 500 grams vs. 499 grams 499 grams – 500 grams / 500 grams X 100 = -.2% 2 grams vs 1 gram 1 gram – 2 grams / 2 grams X 100 = -50%

15. Using Scientific Measurements *Precision can be determined by significant figures *Significant figures are all digits in a measurement known with certainty, plus the last digit that is estimated

16. Determining Significant Figures *Determining significant figures involves a set of rules summarized on p.47 of text *Examples: 100, 100.01, .800, .00180, 1002 *Practice Problems: 3.0 ____ .10004 ____ .0020 ____ 3000 ____ 2.4421 ____

17. Try these yourself! 42.0040 ____ 53.00 ____ 200. ____ 6.300 X 104 ____ 5.00700 X 10-6 ____

18. Using Significant Figures *When adding and subtracting, the number of digits after the decimal in the final answer can’t be more than the least number of digits after the decimal in any of the individual measurements *Examples:

19. 22.11 + 45.6 = 67.71 = 67.7 3000. – 272 = 2728 = 2728 190. + 9.2 = 199.2 = 199 18.111 – 9.44 = 8.671 = 8.67

20. Using Significant Figures *When multiplying and dividing, the number of significant figures in the final answer can’t be more than the least number of significant figures in any of the individual measurements *Examples:

21. 27.926 X 13.0 = 363.038 = 363 3.2 X 105 X 9.86 X 10-3 = 3.1552 X 103 = 3.2 X 103 1.764 X 104 / 4.41 X 102 = 40 = 4.00 X 101 .365 / .200 = 18.25 = 18.3

22. Problem Solving in Chemistry *Key Steps: Analyze (identify known and unknown) Plan Compute Evaluate (units, reasonable, sig. figs.) *See examples in lecture guide

23. 1. Convert 14 cm to meters. 14 cm X 1 meter / 100 cm = .14 m 2. Convert 1.47 X 105 mm to kilometers. 1.47 X 105 mm X 1 meter / 1000 mm X 1 km / 1000 m = .147 km

24. 3. A buret delivers .15 cm3 of water per second. How much time is required to transfer 18 grams of water? Assume 1 cm3 = 1 gram for water. 18 grams X 1 cm3/ 1 gram X 1 second / .15 cm3 = 120 seconds 4.The density of an object is 7.5 g/ml. Calculate the mass in grams of a 1.2 L sample. 1.2 L X 1000 ml/1 L X 7.5 g / 1 ml = 9.0 X 103 g

25. 5. A ant travels at a speed of .005 km/day. Convert to cm / ms. .005 km / day X 1000 m / 1 km X 100 cm / 1m X 1 day / 24 hours X 1 hour / 60 min X 1 min / 60 s X 1 s / 1000 ms = 6 X 10-6 6. A 3% by mass solution of hydrogen peroxide contains 3 grams of hydrogen peroxide per 100 grams of hydrogen peroxide solution. Calculate how many grams of hydrogen peroxide are contained in 56.5 g of a 3% hydrogen peroxide solution.

26. 56.5 g solution X 3 grams of hydrogen peroxide / 100 grams solution = 1.70 g hydrogen peroxide