Download History of the Atom Model

History of the Atom Model
450 BC
Democritus (Greek)World was made of 2 things:
1. Empty space
2. Tiny particles call atoms
(Atomus= indivisible)
Air, earth, fire & water
Aristotle (Greek)Matter is continuous and not
made of smaller particles
PROBLEM: Neither had any evidence.
History of the Atom Model
1782
Antonine Lavoisier (French)-
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
1799
Joseph Proust (French)-
Law of Definite Proportions
Atoms must combine in whole number ratios.
H20
vs
H0 ½
History of the Atom Model
1799
Joseph Proust (French)-
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
TRUE
1. All matter is made up of atoms.
Atoms are the smallest
fundamental units of matter.
Dalton’s Atomic Theory
TRUE
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.
Dalton’s Atomic Theory
TRUE
1. All matter is made up of atoms.
Atoms are the smallest
fundamental units of matter.
FALSE
2. All elements consist of atoms
which are indivisible &
Nuclear reactions
indestructible.
Dalton’s Atomic Theory
TRUE
1.
FALSE
2.
Nuclear reactions
All matter is made up of atoms. Atoms are the smallest
fundamental units of matter.
All elements consist of atoms which are indivisible &
indestructible.
3. All atoms of the same element are
identical in size, shape & mass.
Dalton’s Atomic Theory
TRUE
1.
FALSE
2.
Nuclear reactions
FALSE
Isotopes
All matter is made up of atoms. Atoms are the smallest
fundamental units of matter.
All elements consist of atoms which are indivisible &
indestructible.
3. All atoms of the same element are
identical in size, shape & mass.
Dalton’s Atomic Theory
TRUE
FALSE
Nuclear reactions
FALSE
Isotopes
1.
2.
3.
All matter is made up of atoms. Atoms are
the smallest fundamental units of matter.
All elements consist of atoms which are
indivisible & indestructible.
All atoms of the same element are identical in
size, shape & mass.
4. Atoms of different elements
are different in size, shape,
& mass.
Dalton’s Atomic Theory
TRUE
FALSE
Nuclear reactions
FALSE
Isotopes
TRUE
1.
2.
3.
All matter is made up of atoms. Atoms are
the smallest fundamental units of matter.
All elements consist of atoms which are
indivisible & indestructible.
All atoms of the same element are identical in
size, shape & mass.
4. Atoms of different elements
are different in size, shape,
& mass.
Dalton’s Atomic Theory
TRUE
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.
FALSE
3.
All atoms of the same element are identical in size, shape & mass
TRUE
4.
Atoms of different elements are different in size, shape, & mass.
FALSE
5. In a chemical reaction, atoms are
rearranged, never created nor
destroyed & they combine in whole
number ratios.
.
Dalton’s Atomic Theory
TRUE
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.
FALSE
3.
All atoms of the same element are identical in size, shape & mass
TRUE
4.
Atoms of different elements are different in size, shape, & mass.
TRUE
5. In a chemical reaction, atoms are
rearranged, never created nor
destroyed & they combine in whole
number ratios.
FALSE
.
Dalton’s Atomic Model
Modern Atomic Theory (MAT)
Developing
1839 Michael Faraday (English)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
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Protons & Electrons
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Lots of empty space
Problem with Plum-Pudding
Model?
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+ and - attract
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+- +- + - ++ -- +- +-++ - +-+
+-+- +-+
Modern Atomic Theory (MAT)
Developing
1909 Ernest Rutherford (English)
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 straight
back because there is a concentrated area
of positive charge (nucleus).
Rutherford’s Atomic Model
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Nucleus- Contains Protons
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Electrons surround nucleus
Lots of empty space
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Problem with Rutherford’s Model?
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+ and - attract
+++ _
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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
1924 Louis de Broglie (French physicist)Wave and particle Model-
1926
Werner Heisenberg (German physicist)-
Uncertainty Principle
Modern Atomic Theory (MAT)
Developing
1926 Erwin Schrodinger(Austrian Physicist)
Charge Cloud Model-
•Basic Parts of the Atom
Nucleus
Electron Cloud
link
ATOM
COMPOSITION
The atom is mostly
empty space
•protons and neutrons in
the nucleus.
•the number of electrons is equal to the
number of protons.
•electrons in space around the nucleus.
•extremely small. One teaspoon of water has
3 times as many atoms as the Atlantic Ocean
has teaspoons of water.
Nucleus is Very Massive
n
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• Protons - Positive Charge
• Neutrons - Neutral
• Electrons - Negative
nn