Atomic Models

Lindsay Jones


Democritus was the first person to consider the exsistence of the atom. He also believed that matter was composed of these new particles called atoms but there was no evidence to support his reasoning.

John Dalton

Dalton had come up with evidence to prove his theory, which knocked Democritus out of the way. In his theory, he had four major points:

1. All elements are composed of indivisible particles that are called atoms

2. Atoms from the same element are identical

3. Atoms from different elements mix into ratios

4. Chemical reactions occur when atoms seperate, join, or rearrange

J.J. Thompson

J.J. Thompson came up with the Cathode Ray Tube experiment which helped him to discover that atoms had a negative charge to them. This negative charge was named the electron of the atom. He used a Plum Pudding model to show the electrons in the atom.

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Ernest Rutherford

Rutherford used what is known as the Gold Foil experiment to discover the nucleus of the atom. This experiment shot an energy beam of particles into a piece of gold foil. (Picture source:
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Eugene Goldstein

Eugene discovered the proton using canal rays. These canal rays had magnetic properties that were the opposite of a proton.

James Chadwick

James used Alpha particles in order to discover the neutron in an atom. He also found that the mass of a neutron was very close to that of a proton.

Max Planck

Planck discovered that atoms and molecules are able to emit energy in quantities that are now known as quanta. The formula, E=hf, is used to describe this relationship. E stands for the energy of the system, h is his constant that is used, and f represents the frequency of the wave.

Albert Einstein

Einstein was able to improve on Plancks theory by looking more into photoelctric effect. He shined light onto a metal, causing electrons to be ejected from the surface of the metal. This formed tiny lumps that he called photons.

Neils Bohr

Bohr used Rutherford and Plancks work to help design a hydrogen atom model. This model included electrons circling around the nucleus of the atom. Not only did Bohr create a hydrogen model, but he used Physics to prove that electrlns occupy certain orbits on different energy levels. (Picture source:
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Heinsenberg created a principle called the Uncertainty Principle. This Principle stated that its impossible to know both location and energy within the electron of the atom. You can only know one and leave the other uncertain.

Louis Victor de Brogile

Brogile suggested that all matter could be described as having wave like properties. He envisioned waves strung out around a circle where the orbits of the atoms were different sizes.


Erwin developed the Quantum Mechanic Model as well as equations that showed the particle for an atom. This equation describes the energy of the electron but the location remains uncertain. The solutions that you get from the equation are called wave functions.

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