1. History of the Atom Activity

2. Warm - Up Make a square using the puzzle pieces on your desk You discover a missing piece to the puzzle. Work by yourself to fit the piece in and make a new square. How does this relate to making a discovery in science?

3. Objective

4. Homework Review History of the Atom PowerPoint on my website, fill in gaps of information

5. Agenda Warm – Up Review Mole HW History of the Atom Research Construction of Timeline Gallery Walk Exit Ticket

6. Working in groups of 4 (6 groups) – 1 computer per group – Class set of textbooks Each person will be assigned four scientists to research Research the scientist Complete chart Share information with the group Construct a timeline of for the history of the atom Project Format

7. Name of Scientist Their Accomplishment – Regarding the atom – Development of the atom Date of discovery Picture of the experiment (if there is an experiment) – – Explain what they found in their experiment Picture of the model of the atom constructed (if there is a picture available) – What is the model of the atom showing? What to Research

8. History of the Atom Notes

9. Democritus (400 BC) All matter is composed of tiny, indivisible parts called atoms Said they could not be divided any further

10. John Dalton (1803) Dalton’s Atomic Theory All matter is composed of tiny indivisible parts called atoms (they can be broken down further, although properties will not be retained) Atoms of the same element are exactly alike, atoms of different elements are different (not all atoms of the same element have the same mass – isotopes)

11. John Dalton (1803) Atoms can combine in simple ratios to form compounds Atoms are neither created nor destroyed - Atoms cannot be destroyed, they simply rearrange in a chemical change, therefore the total amount of atoms remains the same

12. John Dalton (1800’s)

13. J.J. Thomson (1897) Plum Pudding Model of the Atom Discovered the electron Worked with Cathode Ray Tubes Discovered particles with a negative charge, electrons – knew they were negative charges by the deflection of the beam from a magnet “Pudding” is positive

14. J.J. Thomson (1897)

15. Discovered that the beam going between the anode and cathode could be deflected by bringing a magnet close to the cathode ray tube. The deflection that Thomson observed showed that the beam must have been made up of negatively charged particles

16. Ernest Rutherford (1911) Gold Foil Experiment – worked with alpha particles Discovered that atoms have a nucleus

17. Ernest Rutherford (1911)

18. Niels Bohr (1914) Electrons occupy different fields or energy levels Based on the fact that atoms appeared to release fixed amounts (quantized) of energy when exposed to heat When an electron is exposed to an energy source, it jumps to a higher energy level When the electron eventually falls back to its original position, energy is released

19. Niels Bohr (1914)

20. Start of the Quantum Mechanical Model Electrons are particles

21. Louis de Broglie (1924) Posed the question, “If light can be viewed in terms of both “wave” and “particle” properties, why can’t particles of matter, like electrons, be treated the same way?” His question/idea was later proved to be correct

22. Erwin Schrödinger (1926) Shows where electrons will probably be found by using the waves they leave behind Electrons are waves Update to the Quantum Mechanical Model Sometimes called the Electron Cloud Model

23. Erwin Schrödinger (1926)

24. Final Thought No model of the atom perfectly describes the behavior of subatomic particles It is difficult to come up with an analogy, because… The only thing that behaves like an atom is an atom

25. Exit Ticket