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BELL RINGER What are the three subatomic particles? (Things smaller than an atom, you learned in 8 th grade)

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Presentation on theme: "BELL RINGER What are the three subatomic particles? (Things smaller than an atom, you learned in 8 th grade)"— Presentation transcript:


2 BELL RINGER What are the three subatomic particles? (Things smaller than an atom, you learned in 8 th grade)

3 History of the Atom

4 Where it all began… 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 Aristotle Democritus

5 Get this… Aristotle believed that all matter was made of ___ elements: ______, ____, ______ and _______. 4Earth AirFire Water Democritus believed that matter was made of small particles called ______ that cannot be _____________. atoms broken down

6 Who WON the debate and who was RIGHT? 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’s ideas then carried through until the _____________. Democritus was actually _______. Aristotle experiments Middle Ages RIGHT

7 A branch of science called _________ was introduced to Europe in ______ AD. Alchemists tried to change ______ to ______. alchemy lead gold What happened next? 1144 “SHOW ME THE MONEY!”

8 Alchemy Symbols Alchemists were ___________ in changing lead to gold – a process called _____________ *(_________ one substance into _______.)* unsuccessful transmutation Changing another

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

10 Who’s Next? 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

11 Thomson’s Experiment Voltage source +- Metal Disks

12 n Passing an electric current makes a beam appear to move from the negative to the positive end Thomson’s Experiment Voltage source +-

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

14 EUREKA! The negatively charged particles were called corpuscles by Thomson but the name was later changed to ________. electrons Thomson developed a model based on his findings and it was called the ____________ model. plum pudding Positive “pudding” Negative “plums”

15 Next up… In _____, an English physicist named _________________ continued Thomson’s work. 1910 Ernest Rutherford He believed the plum pudding model was correct, but wanted to discover the _____ of atoms. size

16 Rutherford’s experiment The radioactive material released ______ particles, which would _____ when in contact with the fluorescent screen. alpha glow To do this… Rutherford used thin ________ sheets and ___________ material. gold foil radioactive

17 Lead block Uranium Gold Foil Fluorescent Screen This is what it looked like:

18 He thought… The alpha particles would pass through the foil without ________ _________. changing direction positive evenly Because… The _______ charges would be spread out _______, and were not close enough together to repel the positively-charged alpha particles.

19 Hypothesis…

20 Why this? Positive “pudding” Positive alpha particles


22 What really happened…

23 Explanation please: + Atoms are mostly ______ ______. empty space There is a ______, _______, ________ charged area at the center of the atom – called the ________. small dense positively nucleus The positive alpha particles were _________ by the nucleus if they got close enough…and thus we have the _______. deflected Nucleus proton

24 Like Charges REPEL! +

25 The Bohr Model The next model of the atom comes from a Danish chemist, _____ _____, who developed it in _____. Niels Bohr In this model the ________ are located in the nucleus and the protons _________ are located in pathways around the nucleus. electrons 1913

26 Modern Model of the Atom The wave mechanical or electron cloud model was introduced in ______ by Schrodinger and Heisenberg. In this model the electrons do NOT follow a set path, they have wiggle room. Because of this you cannot predict the location of an electron at a given time. 1926

27 Last but not least… James _________ discovered the last subatomic particle in _____. The _______ was so difficult to find because it does not have a ______, it is _______. Chadwick’s discovery earned him the nickname: ______________ (sound familiar?) Chadwick 1932 neutron chargeneutral Jimmy Neutron

28 BELL RINGER Name a scientist who helped with the history of an atom and tell what he explained about the atom.

29 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!

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