atomic theory 1. what happens in vegas stays in vegas
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Atomic Theory 1
What Happens in Vegas stays in Vegas
Atomic Theory
Theories in science are proposed to explain the evidence available at the time.
As new evidence is discovered theories are adapted to explain new data.
This is the nature of Science.
In the future this will continue.
DemocritusPlato
460-370 BC
Atoms make up the world
Aristotle
Plato
384-322 BC
Four Elements
Teacher of Aristotle
Aristotle
Wind
Fire
Water
Earth
dryness
wetness
coldness hotness
conflictharmony
The Four Element Theory PropertiesForces
The Four Element Theory lasted for about 2 thousand years because no one tested the theory with scientific experiments.
It was not a scientific theory- which is tested by experiment.
John Dalton
1766-1844
Atomic Theory
Dalton’s Atomic Theory- 1808
Evidence1. The Law of Conservation of Mass2. The Law of Constant Composition- water is 11 % H
and 89 % OTheory1. Each atom is an indestructible and unique spherical
particle2. Atoms combine in simple whole number ratios to
form compounds
Hydrogen
Oxygen Lithium
Dalton Theory- Water
1 g H1 g H
16 g O 18g O
16 g O
1 g H 1 g H
Dalton Theory- Water
18g O
= 11% H
16 g O
1 g H 1 g H
Dalton Theory- Water
2 g H
18 g H2Ox 100% 89 % O
Still11 % H89 % O
Having a molecule (atoms combine in simple whole # ratios) explains the law of constant composition.
No matter how much water you have its still 11% H
2H2 + O2 2H2O
If the atoms are not destroyed then the mass does not change
J. J. Thomson 1871-1937J. J. Thomson 1871-1937
The Thomson Theory of the AtomEvidence1. The electrical nature of matter
beta particlesstatic electricitycurrent electricity
Theory1. The atom is made up of positive material with negative particles throughout- like blueberries in a blueberry muffin.
+ + - + - + +
- + -+ - + - + - + + - +
+ - + -+ - + - +
+ - + -
The Thomson Atom 1903
Ernest Rutherford 1871-1937Ernest Rutherford 1871-1937
The Rutherford Atom 1911SimulationEvidence: Gold Foil Experiment1. 99.99 % of alphas are not deflected2. 0.01 % of alphas are radically deflectedTheory1. Most of the atom is empty space.2. There is a small dense nucleus in the center of the
atom that makes up most of the mass. Electrons circle the nucleus randomly.
The Rutherford Atom 1911Scale: nucleus is home plate; atom is the baseball field
Be
-
-
-
-Nucleus- 4 protons and 5 neutrons
Electrons
Nucleus- is small but has most of the mass
Cornelis Escher 1898-1972Cornelis Escher 1898-1972
Discovery of the Nucleus
Size of the Atom