1. Welcome to another fun filled day in chemistry! In your notes: 1. Using the following reaction, name all of the elements and compounds and state the reactants and products: Mg + Cl 2 → MgCl 2 2. Write 24,000 ml in scientific notation.

2. Demonstration §Using complete sentences, predict how this demonstration works.

3. Aluminum Activity

4. Ion quiz #2: Do on the same sheet as ion quiz #1 1.Be +2 2.Sulfate 3.Peroxide 4.S -2 5.Ca +2 6.Zinc 7.Carbonate 8.Cr 2 O 7 -2 9.SO 4 -2 10.Sulfide

5. Measurements in Chemistry

6. Qualitative Measurements?: Quantitative Measurements?:

7. A type of quantitative measurement is SCIENTIFIC NOTATION... Scientific Notation - written as a coefficient and 10 raised to a power 4Coefficient must be greater than 1 and less than 10 4The exponent (power) indicates the number of times the decimal has been moved 36,000 = 3.6 x 10 4 0.00000085 = 8.5 x 10 -7

8. Accuracy and Precision Accurate and Precise Precise, but not accurate Not accurate and not precise Accuracy - how close your measurements are to the actual or true value Precise - how close your measurements are to each other

9. Sample Data: Is it accurate, precise, both or neither? The following lab groups want to get 25 grams of sugar

10. Error and Percent Error Error = experimental value - accepted value Percent Error = error / accepted value x 100% What is the percent error of the Stacy’s sample data on the previous page? 32.5g - 25g = 7.5g error % Error = 7.5g / 25g = 30%

11. Sig Figs!!! Significant Figures - the digits in a measurement that are known, not estimated **When you measure something, you should always estimate one number past the markings The line is 2.98cm long

13. 1. All non-zero numbers ARE significant Ex: 167 has 3 significant figures (sig figs) 5.4 has 2 sig figs 2. Zeros between significant figures ARE significant Ex: 1008 has 4 sig figs 1.06701 has 6 sig figs 3. Zeros at the end of a number and to the right of the decimal ARE significant Ex: 4.00 has 3 sig figs 3.0 has 2 sig figs 4. Zeros at the end of a number that does not have a decimal ARE NOT significant Ex: 100 has 1sig fig 2280 has 3 sig figs Sig Fig Rules:

14. 5. Zeros at the end of a number that have a decimal ARE significant Ex: 100. has 3 sig figs 2280. has 4 sig figs 6. Zeros in front of a number and to the right of a decimal ARE NOT significant Ex: 0.0002 has 1 sig fig 0.0941 has 3 sig figs YIKES - Are you overwhelmed with sig figs yet?!?!?

15. Then take a break and check out the mountain I climbed this summer! : ) 14,421 feet: how many sig figs is this?

16. Ion and Element Quiz 1.Boron ion 2.PO 4 -3 3.As 4.Gold 5.K 6.Xe 7.Pb 8.Magnesium 9.Bromine 10.Co

17. And you thought you were done with sig figs… Determine the number of sig figs in each of the following: 0.30 mm 150 mL 150. mL 8.009 cm 2500. L 60.0 pm 0.0080 nm

18. Adding and Subtracting Sig Figs Sig Fig Math Answer will be in the least number of decimal places 24.0 --> 1 decimal place 40.64 --> 2 decimal places + 1.007 --> 3 decimal places 65.647 --> will be rounded to 1 decimal place = 65.6 145.685 --> 3 decimal places - 5. 31 --> 2 decimal places 140.375 --> will be rounded to 2 decimal places = 140.38

19. Multiplying and Dividing Sig Figs Answers will be in the least number of sig figs 20.01 4sig figs x 0.057 2 sig figs 1.14057 answer will be rounded to 2 sig figs = 1.1 15.80 / 10.5 = 1.504761905 4 sig figs 3 sig figs answer will be rounded to 3 sig figs = 1.50

20. Sig Fig Math Practice: 1. 186 - 24.00 = 2. 60.42 + 3.0089 = 3. 7.05 * 0.800 = 4. 860.4 / 90. = 5. 5.3 x 10 2 * 6.7 x 10 -3 =

21. “I’m so tired of sig figs”