2. History of Atomic Structure Atoms and their parts

3. History of the atom Starts not with the ________ of the atom, but the ______ of the atom. More than ______ years ago, (around ____ BC) Greek philosophers ___________ and ____________ debated the nature of the universe. history idea 2000 Aristotle Democritus 400

4. History of the Atom Aristotle believed that all matter was made of ___ elements: ______, ____, ______ and _______. 4Earth AirFireWater Democritus believed that matter was made of small particles called ______ that cannot be ___________. atoms subdivided

5. Early Theories…

6. Who WON the Debate? Neither of them really did _____________. Democritus based his theory on ____________, Aristotle based his on __________. Neither of them really did _____________. observation philosophy __________ argued louder, so he won. Aristotle Democritus experiments

7. Who Was Right? Aristotle’s ideas carried through until the _____________. A branch of ‘science’ called _________ was born. Alchemists tried to change ______ to ______. Middle Ages alchemy lead gold

8. Alchemy

9. Alchemical Symbols Alchemists were __________ in changing lead to gold – a process called _____________ (_________ one substance into _________.) unsuccessful transmutation Changing another

10. Who’s Next? In 1661, a chemist named ________ _______ believed that all matter was made of simple substances called _________ that could not be ____________ or _____________. Robert Boyle elements decomposedbroken down Boyle’s theory was not _________ for more than ____ years, since he had no way to ______ his theory. accepted 100 prove

11. Father of Atomic Theory Modern atomic theory was developed in 1809 by an English scientist named _____ ________. His theories were based on ___________ and ____________. John Dalton observations experiments

12. Dalton’s Atomic Theory 1. _______ is made of small particles or ______. Matter atoms 2. Atoms cannot be ________ or _________. created destroyed 3. All atoms of an element are ________ and have the same _____. identical mass 4. Atoms of different elements have different _______. masses 5. ___________ are formed by combining different elements. Compounds

13. Dalton’s Atomic Theory

14. Parts of Atoms In _____, an English physicist named ______________ did experiments to determine the parts that make up the atom. 1897 J.J. Thomson He created a ________ ray tube: a _______ tube where all the ____ has been pumped out and a limited amount of other ______ is pumped in. cathode vacuumair gases

15. Thomson’s Experiment Voltage source +- Metal Disks

16. n Passing an electric ________ makes a beam appear to move from the ________ to the ________ end Thomson’s Experiment Voltage source +- current negativepositive

17. Voltage source Thomson’s Experiment n By adding an electric field to the _______ of the tube, he discovered that the moving pieces were _________. + - outside negative

18. Thomson’s Model The negatively charged particles were _________ electrons plum pudding positive removed Said the atom was like ____________ A bunch of ________ stuff, with the electrons able to be ________.

19. Rutherford’s Experiment In _____, an English physicist named _________________ continued Thomson’s work. 1910 Ernest Rutherford He believed the plum pudding model was correct, and he wanted to discover the _____ of atoms. size Rutherford used thin __________ sheets and ___________ material. gold foil radioactive

20. Rutherford’s experiment The radioactive material released ______ particles, which connected with a fluorescent screen and caused it to _____. alpha glow This is what it looked like:

21. Lead block Uranium Gold Foil Fluorescent Screen

22. He Expected: The alpha particles to pass through without ________ _________ very much. changing direction positive evenly Because… The ________ charges were spread out _______, and were not enough to stop the positively-charged alpha particles.

23. What he expected

24. Because

25. Rutherford thought the mass was evenly distributed in the atom

27. What he got

28. How he explained it: + Atoms are mostly ______ ______. empty space There is a ______, _______, ________ piece at the center of the atom – called the ________. small densepositive nucleus Positive alpha particles are _________ by the nucleus if they get close enough… deflected Nucleus

29. +

30. Modern View of the Atom There are _____ different types of particles that make up the atom. three

31. Parts of the Atom Protons have a ________ charge and are located inside the ________. positive nucleus Neutrons have a ________ charge and are located inside the ________. neutral nucleus Electrons are very _______ particles that have a ________ charge and are found _________ the nucleus. small negative orbiting

32. The Bohr Model Our modern model of the atom comes from a Danish chemist named _____ _____, who developed it in _____. Niels Bohr _________ and _________ are located in the nucleus. Protons neutrons _________ are located in orbit around the nucleus. Electrons 1913

33. Make a TIMELINE! Using your notes, make a timeline of Atomic Events in History! Use the paper provided and the colored pencils! Make it creative, but ACCURATE! Include pictures, too!