1. 1/27 Bell Work Charles Pompuss travels around the world buying expensive art pieces and gems. He always insists on wearing dark glasses when he negotiates to hide his eyes.  What is the reasoning for his peculiar behavior?

2. 1/27 Schedule  Finish Work, Energy, Heat Test  Black Box Activity – 10-15 minutes  Notes Ch 4.1 “Development of Atomic Theory”  Con Rev Ch 4 “Atoms” due TBA Assignments: 1. Dev of Atomic Theory sheet due WEDNESDAY

4. “Black Boxes”  Work in desk groups.  DO NOT OPEN, but attempt to figure out what is in the container.  Compare answers with other groups. Can’t see the objects or atoms…

5. Ch 4.1 “Development of Atomic Theory” Objectives 〉 Describe how Democritus, Dalton, Thomson, and Rutherford’s ideas contributed to understanding of atoms. 〉 Compare/contrast different models of the atom.

6. Beginning Atomic Theory Democritus 〉 4 th Century BCE 〉 Greek philosopher 〉 Universe was made of indivisible, indestructible units called atoms.  Democritus did not have evidence for his atomic theory.

7. Dalton’s Atomic Theory Dalton (1808) 〉 Atoms of an element are exactly alike, indivisible, and join to form compounds. 〉 Used experiments and Evidence  Law of definite proportions : A chemical compound always contains the same elements in exactly the same proportions by weight or mass.

8. Thomson’s Atom Subatomic particles discovered (1897) 〉 Experiments with cathode-ray tubes. 〉 Run electricity through gas in a sealed tube. 〉 Noticed a stream of particles. If the particles bend AWAY from a negative charge, what charge are they? Vintage cathode-ray tube

9. Thomson’s Atom Thomson’s Model  Discovered negative particles… electrons.  He called his model the plum-pudding model. Atoms are NEUTRAL, so there must be positive AND negative particles. Plum-pudding model.

10. Rutherford’s Atom Rutherford’s Planetary Model (1911) 〉 Intended to study Thomson’s model. 〉 Conducted an experiment with gold foil and alpha particles. 〉 Expected alpha particles to pass though, BUT they were deflected.

11. Rutherford’s Model of the Atom, continued Rutherford discovered the nucleus.  Nucleus: an atom ’ s central region, which is made up of protons (+) and neutrons (0)

12. Ch 4.2 “The Structure of Atoms” Objectives 〉 Compare/contrast protons, neutrons, and electrons. 〉 Distinguish between atoms and isotopes. 〉 Identify the unit for atomic mass.

13. Structure Review Atoms are very small, and they are made up of even smaller subatomic particles.

14. Structure Review 1. In the diagram, A is the center of an atom. What is the center of an atom called? 2. The center of an atom is made up of positively charged particles and particles that have no electrical charge. Name the two particles. 3. Negatively charged electrons are found in clouds outside the center of an atom. Why are electrons attracted to the center of the atom?

15. Subatomic Particles 3 Major subatomic particles 〉 Protons, neutrons, and electrons 〉 Differ in charge, location in atom, and mass.

16. Subatomic Particles Protons and Electrons  Each element has a unique number of protons.  Atoms have no overall charge.  Protons – Electrons = 0.  Electric force holds the atom together.  Positive protons are attracted to negative electrons.

17. Atomic and Mass Number  The atomic number equals the number of protons.  The mass number equals the total number of subatomic particles in the nucleus (protons and neutrons)

18. Atomic Number and Mass Number, continued

19. Isotopes Isotopes : Atoms of the same element with different numbers of neutrons.

20. Isotopes, continued Some isotopes are more common than others.  radioisotopes : unstable isotopes that emit radiation and decay into other isotopes Calculate neutron number.  neutrons = mass number – atomic number

21. Solar Oven Project Project is due TOMORROW. Turn in… 1. Experiment Organizer chart 2. Directions to create oven 3. Data tables and Calculations  Temp and time both inside and outside oven  Convert Fahrenheit to Celsius  Specific Heat of Aluminum 4. Final Conclusion paragraph  Effectiveness  Changes to original plan and WHY  Cost / global applications

22. Choose the correct spelling for this often misspelled word. Watch the video if you want to hear it action.video  ukulele  ukalale  ukalele 2/7 Bell Work

23. 2/7 Schedule  Atomos Review  Note Ch 4.2 cont’d  Last day for Solar Oven!! HW: Molar Mass Worksheet Notes: 1.Development of Atomic Theory – LATE 2.QL Modeling Isotopes due MONDAY 3.Molar Mass Worksheet due MONDAY

24. Atomos Watch the video clip, and be able to answer the following questions.video clip  Which of your vocabulary terms came from “atomos”?  Name and describe AT LEAST two atomic models we have already talked about.  Name and describe one of the more modern atomic models.

25. Atomic Masses Unified atomic mass unit : a unit that describes the mass of an atom or molecule;  Defined as 1/12 the mass of a carbon atom with mass number 12  aka mass of a proton or neutron  symbol, u or amu

26. Atomic Masses Average atomic mass is a weighted average. –Isotope abundance determines the average atomic mass. –Ex: Chlorine-35 is more abundant than chlorine-37, so chlorine ’ s average atomic mass (35.453 u) is closer to 35 than to 37.

27. Weighted Average Problems Atomic masses are weighted averages that take into account the number of items and the value of each.  A student has 4 As, 10 Bs, 3 Cs, and 1 F. Use a four point scale to figure out their average grade.  Sabrina has 4 quarters, 6 dimes, 9 nickels, and 15 pennies. What is the average value of the coins?

28. Atomic Masses, continued The mole is useful for counting small particles.  mole: the SI unit used to measure the amount of a substance whose number of particles is the same as the number of atoms of carbon in exactly 12 g of carbon-12 (abbreviation, mol)  1 mol = 602, 213, 670, 000, 000, 000, 000, 000 particles  This number, 6.022 × 10 23, is called Avogadro ’ s number.

29. Atomic Masses, continued Moles and grams are related.  molar mass = the mass in grams of one mole  Ex: 1 mol of carbon-12 atoms has a mass of 12.00 g, so the molar mass of carbon-12 is 12.00 g/mol  You can convert between moles and grams.

30. Math Skills * Use the periodic table to find molar mass. Average atomic mass of an element is equal to the molar mass. Unknown:mass of iron = ? g Fe Converting Moles to Grams Determine the mass in grams of 5.50 mol of iron. 1. List the given and unknown values. Given: amount of iron = 5.50 mol Fe molar mass of iron = 55.84 g/mol Fe*

31. Math Skills, continued 2. Write down the conversion factor that converts moles to grams. The conversion factor you choose should have what you are trying to find (grams of Fe) in the numerator and what you want to cancel (moles of Fe) in the denominator. 3. Multiply the amount of iron by this conversion factor, and solve.

32. Atomic Masses Compound molar masses  Add the molar masses of the atoms in a molecule.  Example: finding the molar mass of water, H 2 O  molar mass of O = 16.00 g/mol  molar mass of H = 1.01 g/mol  molar mass of H 2 O = (2 × 1.01 g/mol) + 16.00 g/mol = 18.02 g/mol

33. Interpreting Chemical Formulas Letters = symbol for elements Subscripts = number of that element/group in the compound Coefficients = number of compound groups 2 hydrogen molecules + 1 oxygen molecule make 2 water molecules