History of the Atom Model 450 BC Democritus (Greek)- World was made of 2 things: 1.Empty space...
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Transcript of History of the Atom Model 450 BC Democritus (Greek)- World was made of 2 things: 1.Empty space...
History of the Atom Model
450 BC
Democritus (Greek)- World was made of 2 things:1. Empty space2. Tiny particles call atoms
(Atomus= indivisible)
Aristotle (Greek)- Matter is continuous and not made of smaller particles
PROBLEM: Neither had any evidence.
Air, earth, fire & water
History of the Atom Model
Antonine Lavoisier (French)-1782
Law of Conservation of Matter (mass)
Matter is neither created Nor destroyed, it is only rearranged.
Mass of reactants = Mass of products
History of the Atom Model
Joseph Proust (French)-1799
Law of Definite Proportions
Atoms must combine in whole number ratios.
H20 vs H0 ½
History of the Atom Model
Joseph Proust (French)-1799
Law of Multiple Proportions
Atoms can combine in different
whole number ratios.
H20 vs H202
Modern Atomic Theory (MAT) Developing
1803 John Dalton (English)-
“Father of Modern Atomic Theory”
Started teaching at 12 years old.
Dalton’s Atomic Theory
1. All matter is made up of atoms. Atoms are the smallest fundamental units of matter.
Dalton’s Atomic Theory
1. All matter is made up of atoms. Atoms are the smallest fundamental units of matter.
TRUE
Dalton’s Atomic Theory
1. All matter is made up of atoms. Atoms are the smallest fundamental units of matter.
2. All elements consist of atoms which are indivisible & indestructible.
TRUE
Dalton’s Atomic Theory
1. All matter is made up of atoms. Atoms are the smallest fundamental units of matter.
2. All elements consist of atoms which are indivisible & indestructible.
TRUE
FALSENuclear reactions
Dalton’s Atomic Theory1. All matter is made up of atoms. Atoms are the smallest
fundamental units of matter.
2. All elements consist of atoms which are indivisible &
indestructible.
3. All atoms of the same element are identical in size, shape & mass.
TRUE
FALSE
Nuclear reactions
Dalton’s Atomic Theory1. All matter is made up of atoms. Atoms are the smallest
fundamental units of matter.
2. All elements consist of atoms which are indivisible &
indestructible.
3. All atoms of the same element are identical in size, shape & mass.
TRUE
FALSE
Nuclear reactions
FALSEIsotopes
Dalton’s Atomic Theory1. All matter is made up of atoms. Atoms are
the smallest fundamental units of matter.
2. All elements consist of atoms which are
indivisible & indestructible. 3. All atoms of the same element are identical in
size, shape & mass.
4. Atoms of different elements are different in size, shape, & mass.
TRUE
FALSE
Nuclear reactions
FALSE
Isotopes
Dalton’s Atomic Theory1. All matter is made up of atoms. Atoms are
the smallest fundamental units of matter.
2. All elements consist of atoms which are
indivisible & indestructible. 3. All atoms of the same element are identical in
size, shape & mass.
4. Atoms of different elements are different in size, shape, & mass.
TRUE
FALSE
Nuclear reactions
FALSE
Isotopes
TRUE
Dalton’s Atomic Theory1. All matter is made up of atoms. Atoms are the smallest fundamental
units of matter.
2. All elements consist of atoms which are indivisible & indestructible.
3. All atoms of the same element are identical in size, shape & mass.
4. Atoms of different elements are different in size, shape, & mass.
5. In a chemical reaction, atoms are rearranged, never created nor destroyed & they combine in whole number ratios.
TRUE
FALSE
FALSE
TRUE
Dalton’s Atomic Theory1. All matter is made up of atoms. Atoms are the smallest fundamental
units of matter.
2. All elements consist of atoms which are indivisible & indestructible.
3. All atoms of the same element are identical in size, shape & mass.
4. Atoms of different elements are different in size, shape, & mass.
5. In a chemical reaction, atoms are rearranged, never created nor destroyed & they combine in whole number ratios.
TRUE
FALSE
FALSE
TRUE
TRUE
Dalton’s Atomic Model
Modern Atomic Theory (MAT) Developing
Michael Faraday (English)-1839
Atomic structure might be related to electricity…it might have a charge.
Ben Franklin (English)-
2 types of charges• Positive (later proton)• Negative (later electron)
Problem with Dalton’s Atom Model?
Lacks subatomic particles…
Modern Atomic Theory (MAT) Developing
JJ Thomson (English)-1897
Cathode Ray Tube Experiment
link
Thomson’s Plum-Pudding Model
- ++ + -
+ - + -+ -
- +- +
-+ + + +- +
- +-+
Protons & Electrons
Lots of empty space
Problem with Plum-Pudding Model?
- ++ + -
+ - + -+ -
- +- +
-+ + + +- +
- +-+
+ and - attract- +
+- +- + - +-+ -- +- +-+-
+ - +-++-+- +-+
Modern Atomic Theory (MAT) Developing
Ernest Rutherford (English)1909
Gold Foil Experiment
link
Modern Atomic Theory (MAT) Developing
The Results & The Explanation
• Most of positive charges passed through because the atom is mostly empty space.
• Some of the positive charges deflected because the atom contains some positive charge.• Some of positive charges deflected straightback because there is a concentrated area of positive charge (nucleus).
Rutherford’s Atomic Model
Nucleus- Contains Protons
Electrons surround nucleus
Lots of empty space
_+++
+++++++
_
__
_
_
_
_
Problem with Rutherford’s Model?
+ and - attract_
++++++++++
_
__
_
_
_
_
++++++++++
_
_
_
__
_
_
Modern Atomic Theory (MAT) Developing
Niels Bohr (American)-1913
Solar System Model-
Electrons are like planets that orbit the nucleus
link
Problem with Solar System Model?
Scientists found this model failed for atoms other than Hydrogen because it couldn’t predict the energy levels of electrons in atoms with more than one electron.
Modern Atomic Theory (MAT) Developing
Louis de Broglie (French physicist)-1924
Wave and particle Model-
1926 Werner Heisenberg (German physicist)-
Uncertainty Principle
Modern Atomic Theory (MAT) Developing
Erwin Schrodinger-
(Austrian Physicist)1926
Charge Cloud Model-
•Basic Parts of the Atom Nucleus Electron Cloud
link
ATOM ATOM COMPOSITIONCOMPOSITION
•protons and neutrons in protons and neutrons in the nucleus.the nucleus.
•the number of electrons is equal to the the number of electrons is equal to the number of protons.number of protons.
•electrons in space around the nucleus.electrons in space around the nucleus.
•extremely small. One teaspoon of water has extremely small. One teaspoon of water has 3 times as many atoms as the Atlantic Ocean 3 times as many atoms as the Atlantic Ocean has teaspoons of water.has teaspoons of water.
The atom is mostlyThe atom is mostlyempty spaceempty space
Nucleus is Very Massive
nn
nn
n n
• Protons - Positive Charge
• Neutrons - Neutral
• Electrons - Negative