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+HAPPY HUMP DAY!!!
Homework DUE now!
Get ready for your element quiz!!!
TEST TOMORROW chem nerds… STUDY!!!
+Element Quiz #2 pg. 301. Cr
2. Co
3. Kr
4. Zn
5. Mn
6. S
7. F
8. Ne
9. Ar
10. Br
11. Nickel
12. Copper
13. Beryllium
14. Sodium
15. Lithium
16. Potassium
17. Iron
18. Arsenic
19. Magnesium
20. Calcium
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Unit 3 The History of the ATOMand Atomic Structures
Dem
ocr
itus
& D
alt
on
Thom
son
Ruth
erf
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Bohr
Sch
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ger
+Democritus
Greek Philosopher
He lived exclusively for his studies (you should try that!)
Known as the laughing philosopher
He called nature’s basic particle an atomos, based on the Greek word “indivisible.”
He considers education to be the noblest of pursuits, but cautioned that learning without sense leads to error. (THERE MUST BE A POINT!!!)
+John Dalton: Dalton’s Atomic Theory
1. All elements are composed of tiny indivisible particles called atoms. Element
A2. Atoms of the same element are identical. The atoms of any one element are different from those of any other elements.
+ Dalton’s Atomic Theory
3. Atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds.
+ Dalton’s Atomic Theory
4. 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.
+Dalton’s Atomic Theory
We now know that certain parts of this theory are invalid.
Part 1 – False. Atoms have been split.
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Part 2 – Partially False. Some atoms of the same element have more neutrons.
Atoms of different elements are different.
Part 3 – True!
Part 4 – True!
+Dalton’s Atom
Dalton viewed the atom as a small indivisible particle
His idea did not hold up once subatomic particles were discovered
+Discovery of Parts of the
Atom
+J.J. Thomson
discovery of the electron (e-) in 1897
disproved Dalton’s theory; atoms DID have different parts after all
Used a cathode ray tube to prove that there were charged particles within the atom
+Thomson Model
(from http://cwx.prenhall.com/bookbind/pubbooks/blb/chapter2/medialib/blb0202.html)
Plum pudding model aka chocolate chip cookie model
+Ernest Rutherford
Born in 1871 in New Zealand
The Nobel Prize in Chemistry in 1908
He discovered the nucleus! In 1911
Buried next to Sir Issac Newton and Lord Kelvin in Westminster Abbey. (way cool!)
+Rutherford said, “Atoms have a nucleus!”
Dense & positively charged
Contains most of the mass of the atom
Contains the protons and neutrons
Electrons are around the outside of the nucleus flying around the empty space
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+Rutherford Model
Nucleus
Empty Space
Electrons
+Bohr Model
Niels Bohr – 1913
Electrons travel in definite orbits around the nucleus
aka “Planetary Model”
+Bohr Model
Nucleus
Electrons(orbiting thenucleus in
energy levels)
+ Quantum Mechanical Model
Erwin Schrodinger – 1926
Electrons DO NOT orbit the nucleus
aka Wave Model
+Electron Cloud
Area where there is a high probability that the electron will reside there 90% of the time
+James Chadwick
Discovered the neutron in 1932
Has a neutral charge
Found in the nucleus
About ½ of the mass of the nucleus
Wanted to know where the extra mass was in an atom; shot particles @ beryllium
Eventually led to experiments to bombard atoms with neutrons –> uranium bombs!
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