History of the Atom Project

Democritus

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Democritus thought that all matter was formed by tiny pieces that could not be cut into smaller parts. He used the word atomos which translate to “uncuttable.” The ideas of atoms began to spread in the 1600s creating many theories to come.

Dalton

Oct 5, 1803

Dalton originally thought that atoms looked smooth, hard balls that could not be broken into smaller pieces. One of his statement is that are look exactly alike and have the same mass unless they have different elements.

Thomson

Oct 5, 1897

Discovered that there were negatively charged electrons. He knew that the Atoms themselves did not have any electric charge. To reason with this he said there had to be a positive charge so that it would balance out the charge. In his model he shows that electrons are scattered in a positively charged ball.

Dmitri

Oct 5, 1905

Dmitri was able to make organise the periodic table after falling asleep and having the answer come to him. He did this by atomic weights of the elements and their relation on how the elements behaved.This discovery is important because it is one of the most iconic images in science and made the elements more easy to understand.

Rutherford

Oct 5, 1911

Rutherford showed that there was a electrons,nucleus, and protons on an atom which was previously unknown. He found this by shooting positively charged particles at a sheet of gold foil to show that some went through the sheet and others curved off in other directions. This is important because it is the bassist to all other models of the atom.

Bohr

Oct 5, 1913

Bohr made a new model of the atom where the electrons all have a specific orbit around the nucleus. This looked like planets around the sun. The electrons all had a fixed energy. This was important because it lead to further advancement in the model of the atom.

Chadwick

Oct 5, 1932

When Chadwick started studying atomic disintegration he noticed that the atomic number was less than the atomic mass. One reason he made was that there were electrons and additional protons in the nucleus. The protons still had their mass, but their positive charge was canceled by the negative electrons.