Atomic History & Atomic Structure!

1. Atomic History & Atomic Structure! • Notebook Add-ons: • P. 22: Unit 1 Test • P. 23: “Unit 2 Key Terms” • P. 24: “Unit 2 Proficiency Tracker” • P. 25: “Atomic Theory Timeline” Chart • P. 26: Periodic Table • P. 27: Title: “Notes: Atomic Structure • P. 28: “Atomic Structure Chart” • Homework! • Finish “Atomic Structure Chart” • Study for Quiz!!! • Start working on your Project! (Due 9/30)

2. Mystery Box • With your table group… try to figure out what is inside the “Mystery Box” • DON’T OPEN IT!!!!  • How small is an atom??? • http://www.youtube.com/watch?v=aQnbF-zpDiM

3. Atomic Theory • Discuss with your table groups your research findings on your scientist.

4. Atomic Theory Timeline Fill in your chart!

5. John Dalton (1803)

6. Dalton’s Postulates • All elements are composed of tiny indivisible particles called atoms. • Atoms of the same element are identical. The atoms of any one element are different from those of any other elements. • Atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds. • Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.

7. Dalton’s Postulates • We now know that certain parts of this theory are invalid. • Part 1 – False. Atoms have been split. • Part 2 – Partially False. Some atoms of the same element have more neutrons. (However, atoms of different elements are different.) • Part 3 – True! • Part 4 – True!

8. Dalton’s Model • Just a tiny ball with no parts inside

9. J. J. Thomson (1897)

10. J. J. Thomson • Used a cathode ray tube to shoot an electrical charge through it. • Saw that the particles were deflected towards the positive end of the tube. • This must mean that atoms contained a NEGATIVE charge! • Discovered the ELECTRON. http://www.youtube.com/watch?v=IdTxGJjA4Jw http://www.youtube.com/watch?v=RW_zfKOU9uM

11. Thomson’s Model • “Plum Pudding” or “Chocolate Chip Cookie Dough” Model. • A ball of positive charge containing a number of electrons.

12. Ernest Rutherford (1911)

13. Ernest Rutherford • Did the Gold Foil Experiment • Shot alpha (positively charged) particles at a sheet of gold foil. • Saw that most particles passed through the foil and some deflected straight back at different angles. • Means that atoms are mostly empty space but contain a densely packed positive center…. • Discovered the NUCLEUS http://www.youtube.com/watch?v=wzALbzTdnc8&NR=1 http://www.youtube.com/watch?v=5pZj0u_XMbc

14. Rutherford Model Dense, positively charged nucleus Surrounded by electrons (mostly empty space) Empty Space Nucleus Electrons

15. Niels Bohr (1913)

16. Niels Bohr • Electrons travel in definite orbits around the nucleus • Electrons are found in “energy levels” • AKA Planetary Model http://www.youtube.com/watch?v=wCCz20JOXXk

17. Bohr Model Nucleus Electrons (orbiting the nucleus)

18. Atomic Structure p. 27

19. Proton Neutron Electron

21. Element Info on the Periodic Table Atomic Number (#protons) Element Symbol Element Name Atomic Mass

22. Other Info • Mass Number = #p + #n • NOT the same as Atomic Mass… you CAN’T find this on the P.T.! • # of electrons: • If #of electrons is the same as the # of protons --- NEUTRAL ATOM • If the # of electrons is NOT the same as the # of protons --- ION

23. Beans activity • A Carbon atom has: • 6 protons • 6 neutrons • 8 electrons • Create a “bean atom” of carbon.

24. Atomic Symbols Mass Number (#protons + #neutrons) Charge (#protons - #electrons) 6C 12 2- Atomic Number (#protons)