1. Group Warm-up
On your group white board draw an Atom….label the structures you remember

2. Atomic Model Theory and how it evolved

3. Video
timeline of discoveries

4. Atomic structure is classified as a Scientific Model….
Nobody has ever seen an atom – it’s too small for microscopes
So far it is the best explanation
Most scientists support it
the model can change when new discoveries are made

5. The word Atom – 400 BC The Greek philosopher Democritus wrote
“The smallest particle of matter is indivisible and indestructible and I will call it “atom”
Atom

6. 1802 - 1st Atomic Theory by John Dalton
1. Matter is made up tiny, indivisible atoms
2. there are different types of atoms called Elements
3. Elements can under go chemical reactions to form Compounds
Different elements

7. First attempt of a Periodic Table
isolated 20 pure substances

8. Discovery of the Electron - 1897
JJ. Thompson’s Cathode Ray Machine

9. The Cathode Ray Machine
Cathode: negative electrode Anode: positive electrode
Observation:
cathode ray beam is attracted to a positive pole and rejected by a negative pole
Conclusion:
The beam is composed of ____________ charged particles
Thompson called them Electrons

10. Plum Pudding Model 1897
New atomic model: negative Electrons are embedded in a positive matrix

11. Discovery of the Nucleus- 1917
E. Rutherford’s Gold Foil Alpha Particle Machine

12. Goldfoil Alpha Particle Machine
Ultra thin gold foil is blasted with Alpha particles (hard, positively charged) They should go straight through the plum pudding!

13. What’s in the center of an atom?
Many Alpha particles go straight through, but a few get deflected at odd angles! Small hard Nucleus in the center

14. 1917- Solar System Model Small, hard positive nucleus in the center
electrons orbit like “planets”
Atoms are mostly empty space filled with negative electrons

15. Bohr’s Model 1920 Niels Bohr, Max Planck
Electrons fly on distinct energy rings

16. 2017 Atomic Model
Electrons are in “clouds” called Orbitals Nucleus Electron Orbital Clouds

17. Warm-up
Sketch Thompson’s experimental set up and explain how he concluded that the Cathode Ray was negatively charged
Sketch Rutherford’s experimental set up and explain how he determined that an atom is mostly empty space but has a small hard nucleus

18. 5. Calculate mass and charge of an element with
A. 8 protons, 8 neutrons and 10 electrons?
16 amu, 2-
B. 15 protons, 17 neutrons, 18 electrons
32 amu, 3-
C. 12 protons, 13 neutrons, 10 electrons
25 amu, 2+
D. 6 protons, 8 neutrons, 6 electrons
14 amu, 0

19. On the back of your stampsheet
Draw the Rutherford’s experimental set-up
Explain why the data it produced were surprising to the scientific community
How did those data change the atomic model

20. Warmup
1. What’s the mass in amu’s of an element with 33 protons and 37 neutrons? 2. Name the element. 3. What’s the mass in grams of an element weighing 23.5 amu’s? 4. What’s the size in meters of an element with 1078 Angstrom?

21. Journal 1. Name the element of the three isotopes shown below
2. Write the two short hands
3. Indicate the # p+, no, e- for each
A B C

22. Isotope Videos
Carbon Isotopes

23. Name the following mean elementsHg Sn Mn Zn As Au Pb At Sb

24. Find the symbol of the following
Manganese
Zinc
Antimony
Mercury
Lead
Arsenic
Tin
Gold
Astatine

25. Find the AAM of
Element Terminium 83.25% amu 6.78% amu 9.97% amu x = amu x = amu x = _2.493 amu rounded to amu