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.
Democritus Plato BC Atoms make up the world
Aristotle Plato BC Four Elements Teacher of Aristotle
Aristotle Wind Fire Water Earth dryness wetness coldnesshotness 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 Atomic Theory
Dalton’s Atomic Theory Evidence 1. The Law of Conservation of Mass 2.The Law of Constant Composition- water is 11 % H and 89 % O Theory 1. Each atom is an indestructible and unique spherical particle 2.Atoms combine in simple whole number ratios to form compounds
Hydrogen Oxygen Lithium
Dalton Theory- Water 1 g H 16 g O 18g O
16 g O 1 g H Dalton Theory- Water 18g O
= 11% H 16 g O 1 g H Dalton Theory- Water 2 g H 18 g H 2 O x 100%89 % O
Still 11 % H 89 % 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
2H 2 + O 2 2H 2 O If the atoms are not destroyed then the mass does not change
J. J. Thomson
The Thomson Theory of the Atom Evidence 1. The electrical nature of matter beta particles static electricity current electricity Theory 1.The atom is made up of positive material with negative particles throughout- like blueberries in a blueberry muffin.
The Thomson Atom 1903
Ernest Rutherford
The Rutherford Atom 1911 Simulation Evidence: Gold Foil Experiment % of alphas are not deflected % of alphas are radically deflected Theory 1.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 1911 Scale: 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 Discovery of the Nucleus Size of the Atom