-
John Dalton
Some Parts of Dalton's Theory
1.) All elements are composed of atoms
2.) In a particular compound, atoms of different elements always combine in the same way.
Dalton showed his theory by making wooden spheres to represent the atoms of different elemenents. -
J.J Thomson
Thomson did many experiments and they showed the first evidence that atoms are made of even smaller particles. One way he showed this was the plum pudding model. This model showed that an atom can still have negative particles but it was neutral. -
Hantaro Nagaoka
Nagoaoka suggested that an atom has a central nucleus and eletrons move in orbits like the rings of Saturn. -
Ernest Rutherford
Rutherford found that that uranium gives of fast moving particles that have a postive charge. He named these particles alpha particles. After he discovered this he ask one of his students, Ernest Marsden to find out what happens to th alpha particles when they go through a thin sheet of gold. Marsden used a model that made the alpha particles go thorugh a slit and through the gold. Around the gold there is a ring to show where the particles go, -
Niels Bohr
Bohr showed the electrons move in spherical orbits at a distance from the nucleus. Bohr showed in his model that each eletron in an atom has a speific amount of energy. -
Frank Hertz
Hertz helped confirm the quantum theory which predicted that eletrons only take up energry only takes up quantized energy states. -
Louis de Broglie
Broglie says that moving particles like electrons have some properties of waves. In some of his experiments electron beams bent through a slit just like light. -
Erwin Schrodinger
Erwin made math equations to show the way electrons move in atoms. His equations lead to the electron cloud model. -
Democritus
Democritus believed that all matter was made up of very small particles that couldn't be divided. He called these particles atoms, But Democritus had no way of showing this. He just thought of it and people accepted it. So it was considered right. -
Aristotle
Aristotle's theory was that there is no limit to how many times matter can be divided. He also thought hat everything was made up of only 4 elements; air, earth, water, and fire. But the thing about Airistotle and many people during his age was that once they someone said something and it was accepted it was considered right. But theory about everything being made up of only 4 elements was proved wrong in the 1800's when scientist had enough information to support an atomic model of matter. -
James Chadwick
Chadwick confirmed the existence of neutrons. Neutrons have no charge, He showed this by using a cloud chamber filled with nitrogen and the radiation cause the nitrogen to recoil. This ment that the neutrons in the nitrogen had no charge,
