1. Today is Monday, September 21 st, 2015 Pre-Class: Today we are reviewing for our exam. The test will be on mixtures, elements, substances, density, sig figs, dimensional analysis (unit conversions), basic atomic structure, and a tiny bit of atomic history.

2. Today’s Agenda Review Game

3. Review Game Rules I will ask a question to the class. Each participant (that’s you) writes down the answer silently. – Not each group…each individual. After a few moments, I will say, “Compare answers.” Each of you will look at what the other wrote.

4. Review Game Rules Did you each get the right answer? – 2 points. Did one of you get the right answer? – 1 point. Neither of you? – For shame. 0 points. – And eternal guilt.

5. Review Game Rules The List of Do Nots: – Do not talk to each other, make noises, gesture, give answers (my discretion here) between when the question has been read and when I say, “Compare answers.” Doing so will result in a disqualification for that round. Don’t believe me? Try it. – Do not fall asleep when I’m getting scores. If you’re not paying attention, I’m not giving you points.

6. Review Question 1 A chunk of Substance X has a mass of 73 g and occupies 75 cm 3. Will it float in pure water? – Yes it will float (density = 73/75 = 0.97 g/cm 3 ).

7. Review Question 2 How many significant figures are in the number 6.02 x 10 23 ? – There are three (count right-to-left).

8. Review Question 3 My dog weighs 19.1 kg. How much is this in grams? – 19,100 grams or 1.91 x 10 4 g.

9. Review Question 4 A sloth can travel a maximum speed of 4 meters per minute. What is this speed in miles per hour? [1 km = 0.621 mi] – ~.1491 miles per hour.

10. Review Question 5 Is soil an example of a compound, a heterogeneous mixture, a homogeneous mixture, or an element? – Heterogeneous mixture.

11. Review Question 6 Is blood an example of a compound, a heterogeneous mixture, a homogeneous mixture, or an element? – Homogeneous mixture.

12. Review Question 7 Is carbon an example of a compound, a heterogeneous mixture, a homogeneous mixture, or an element? – Element.

13. Review Question 8 Express 0.0029 in scientific notion. – 2.9 x 10 -3

14. Review Question 9 Express 0.84 in scientific notion and with three significant figures. – 8.40 x 10 -1

15. Review Question 10 Which weighs more, a proton or an electron? – Proton.

16. Review Question 11 Where are electrons located? – Around the nucleus moving at high speeds.

17. Review Question 12 When the number of electrons in an atom changes, what is created? – Ion (or a positive/negative charge).

18. Review Question 13 BONUS NON-CHEMISTRY QUESTION You may wager any/all of your points. Category: Not Chemistry Which was the first European country to settle the island of Manhattan? – Holland/The Netherlands (The Dutch)

19. Review Question 14 There are three isotopes of Carbon – C-12, C- 13, and C-14. If the atomic mass of Carbon is approximately 12.001 amu, which isotope is most common? – C-12.

20. Review Question 15 How many grams are in 8.93 kilograms? – 8930 grams.

21. Review Question 16 Express the number 0.0089303 in scientific notation. – 8.9303 x 10 -3

22. Review Question 17 Element Atomic Number Mass Number ProtonsNeutronsElectrons As3342 115 4398 15094 O16 Complete the table. Note: All atoms are neutral.

23. Review Question 17 Element Atomic Number Mass Number ProtonsNeutronsElectrons As3375334233 B511565 Tc4398435543 Pu942449415094 O816888

24. Review Question 18 What is the atomic number of an atom with 34 protons and 37 neutrons? – 34 (also happens to be selenium).

25. Review Question 19 How many milliliters in a deciliter? – 100

26. Review Question 20 How many neutrons does an F-20 atom have? – 11

27. Review Question 21 How many neutrons and protons does an F-20 atom have? – 20

28. Review Question 22 Copper has two main isotopes, Cu-63 and Cu- 65. Use copper’s mass on the periodic table – which isotope is more abundant? AND How can you tell? – Cu-63, since Cu’s atomic mass is 63.55. That’s closer to 63 than to 65.

29. Review Question 23 Which weighs more, a neutron or an electron? – Neutrons. Electrons weigh virtually nothing in comparison.

30. Review Question 24 Add the following numbers and express the answer in significant figures: 256.1 g + 14.51 g + 506.123 g – 776.7 grams.

31. Review Question 25 What’s the difference between a mass number and an atomic mass? – Mass number = # of protons + # of neutrons. – Atomic mass = weighted average of isotopes’ masses.

32. Review Question 26 Ions differ in the number of which subatomic particle? – Electrons.

33. Review Question 27 When salt dissolves into a beaker of water, is it a chemical change or a physical change? – Physical.

34. Review Question 28 Isotopes differ in which subatomic particle? Are their atomic numbers different? Mass numbers? – Neutrons. – Atomic number never changes. – Mass number (protons + neutrons) does change.

35. Review Question 29 The total mass of three products in a chemical change is 43.5 grams. What is the total mass of the reactants, if there were only two? – 43.5 grams – Law of Conservation of Mass.

36. Review Question 30 56 metal spheres each weighing 4 grams are dumped into a large graduated cylinder. The water rises from 29 mL to 41 mL. What is the density of the spheres? – 56*4 = Total Mass – 41 mL – 29 mL = 12mL = Volume – 224/12 = 18.667

37. Review Question 31 During an experiment, a chemist finds the density of aluminum to be 2.58 g/cm 3. The textbook, however, lists the density as 2.70 g/cm 3. What is the percent error of the chemist’s calculation? – |(estimated – actual)| / (actual) x 100 = % error – |(2.58 - 2.70) / (2.70)| x 100 = 4.44%

38. Review Question 32 Is ice an element, compound, homogeneous mixture, or heterogeneous mixture? – Compound.

39. Review Question 33 6.1 x 4.32 = ??? in significant figures. – 26