1. 1/19/16
Pg 2 7 Dead Dudes of Atomic Theory P1 (Pg 3) AT/ATOMS ToC (pgs 1/2) IN ?: How or why are things/new concepts discovered?

2. Atoms & The 7 Dead Dudes of Atomic Theory

3. any of several theories proposing that matter is composed of atoms
What is atomic theory?
any of several theories proposing that matter is composed of atoms
atoms: smallest particle of matter than can build to create objects around you

4. Ancient Greece: nothing to do!
If atoms are so small, how were they discovered?!
Ancient Greece: nothing to do!
Around 440 B.C., Greek dude/philosopher Democritus was eating grapes & a coin 1 day

5. Wondered what was IN the coin
No experimental data to support
his idea
Based on careful thinking &
reasoning

6. Said you could only cut the coin to a certain point, its smallest piece
Called the ‘atomic hypothesis’
Said that smallest part was uncuttable
Called it an atom
Atomos - “indivisible”

7. Between atoms, there lies empty space
Are indestructible
Atoms have always been, and always will be, in motion

8. There are an infinite number of atoms, and kinds of atoms, which differ in shape and size.
- ‘mimic’ their material
sweet things are made of smooth atoms, bitter things are made of sharp atoms, etc.

9. How was atomic theory advanced?
John Dalton was a British chemist & teacher
Stated his theory in 1803
Agreed w/Democritus: elements (stuff) are made of tiny particles called atoms
Aren’t different shapes, though! All little spheres!

10. Heavier material = bigger atom
Dalton vs Democritus
Atoms of a given element are different from those of any other element due to their mass/size
Heavier material = bigger atom

11. All atoms of a given element are
identical
All gold atoms look the same
Group together = bar of gold

12. Called Law of Multiple Proportions Build compounds
Why does different size matter?
Atoms of different elements combine in a specific ratio (ie: water = H2O) based on mass
Called Law of Multiple Proportions
Build compounds

13. Atoms can’t be created, divided into smaller parts, or destroyed; they just rearrange themselves to make new stuff

14. OUT ?:
{DON’T COPY} Pick a school appropriate material. {COPY} Draw what Democritus would believe the atom of that material would look like.

15. Make a Venn diagram of Democritus’ & Dalton’s theories.
1/20/16
Pg 4
IN ?:
Make a Venn diagram of Democritus’ & Dalton’s theories.
7 Dead Dudes of Atomic Theory Pt 2 (Pg 5)

16. When was the next change made to the
A.T.?
1897, JJ Thomson discovered smaller particles in the atom
Proved atoms could be divided, or broken down
Used a cathode ray tube & found a positively charged plate attracted a beam of electricity
Decided something NEGATIVE had to be in atom to be attract to the + plate

17. What did he call his discovery?
Called the negative particles corpuscles
Now called electrons
Where were the negative particles in the atom?
Said they were evenly spread out in the positive atom, & that all atoms had the same #
Called plum-pudding model

18. What would we possibly call this model today
What would we possibly call this model today? Provide evidence to support your choice. Record your answer on your notes page.
Why do you think the next scientist disagreed with this model? Discuss & answer on notes page.

19. Why was Thomson’s theory changed?
Had research students; former student from New Zealand discovered a new structure to the atom
Ernest Rutherford, 1911

20. How did Rutherford make his discovery?
Gold foil experiment
Shot a + beam of alpha sheet of gold foil
Beam was turned around in various ways & some deflected (90o) by gold foil
MOST particles went THRU the gold foil
Mostly empty space
Tiny, dense nucleus

21. What changes did his experimental results lead to?
stated there must be a + core to the atom
Tiny, very dense center called the nucleus
Most of mass of atom is here
100,000x smaller than whole atom
Core contained + particles called Protons
Agreed w/Thomson that electrons were evenly dispersed around outside of atom

22. How long before the next discovery/change to theory?
1913, Niels Bohr
stated the atom had a certain structure outside of nucleus
Electrons were located in specific paths, or rings
Also known as ORBITals
Called the ‘planetary model’

23. Are all the electron rings the same?
Each ring held a certain amount of NRG/electrons
2/8/18
Move away from nucleus = higher level = lower NRG
e- strongest closest to nucleus
**What other concept have we learned that this idea is similar to? (answer on note page)
e- could move from level to level
Gain or release NRG when they move from level to level
Form of light (PHOTONS)

24. OUT ?:
How was Thomson’s model different from Democritus’ original definition of an atom?

25. 1/21/16 Pg 6 7 Dead Dudes of Atomic Theory Pt 3 (Pg 7) IN
1/21/16 Pg 6 7 Dead Dudes of Atomic Theory Pt 3 (Pg 7) IN ?: Use the pink IQ provided.

26. Do we still think atoms look like the planets?
Erwin Schrodinger
1926, stated that electrons were in certain levels, but more like a cloud vs. a set ring/path
Can’t really locate WHERE electrons any given time
Created a mathematical probability of electron location
Not last model, but still considered CURRENT MODEL

27. Areas surrounding the nucleus are like levels of atmoshpere – “clouds”
What does the current atomic model look like?
Areas surrounding the nucleus are like levels of atmoshpere – “clouds”
What issue is caused by the nucleus ONLY containing protons?

28. Why didn’t the + nucleus particles REPEL & explode?
James Chadwick; 1932
proved the existence of the 3rd particle inside atoms
called neutrons

29. What’s the purpose of this 3rd particle? ‘binding’ in the nucleus
neutral, or no charge
creates the STRONG force/’glue’
keep the protons from repelling each other & exploding nucleus
neutrons + + + +
protons
Notice the neutrons & protons are about the same size!

30. Where are the neutrons located in Chadwick’s model?
Adding to Rutherford’s nucleus
No charge, so nucleus is still + from protons
What does the nucleus look like?

31. Use the pink OQ provided.
OUT ?:
Use the pink OQ provided.