Atomic Models

Over the years as science has become more popular, more and more discoveries and theroies have came about. This is especially true for the atom. Over the years there have been many different models of the atom.


To start with was the Greek model that was formed by Leucippus and Democritus. These were the first to ever describe the model, but we never learned much about this.


Next was Dalton'd model. This is still the most widely accepted model, the following models only changed Dalton's theory a slight bit.
Dalton stated that :

• all elements are composed of tiny indivisible particles called atoms (this is not true today)
• Atoms of the same element are identical. The atoms of any one element are different from those of any other element
• Atoms of different elements can physically mix together or can chemicallly combine in simple whole-number ratios to form compounds.
• Chemical reactions occur when atom are separated, joined, or rearranged. Atoms of one element however are never changed into atoms of another element as a result of a chemical reation.

Following Dalton's theory, along came Thompson. He proved that atoms  were in fact divisible by discovering the electron. He discovered the electron by passing electrical currents through a cathode ray, and found that the electrons went to the positive end and the protons went to the negative end. He came up with the "plum pudding" model.

Next came Rutherford. Rutherford was known for discovering the nucleus. He found the nucleus to be in the center of an atom, made up of protons and neutrons.

After that the Bohr model came about. Bohr believed that electrons were only found in specific orbitals around the nucleus.

Finally the most recent model, the Quantum Mechanical model. This model sets up the basis for electron configuration. It determines the allowed energy an electron can have and how likely it is to find the electron in various locations around the nucleus.