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How the Atomic Theory has changed over time
This is a timeline about how the Atomic Theory changed from the year 1800 to 1945. -
Dalton publishes an article
In 1803, Dalton published an article for the Manchester Literary and Philosophical Society. In this article, the talked about his chart of atomic weights for each of the elemends that were known at this time. -
Dalton publishes a book on chemistry
Dalton published a book in 1808 called "A New System of Chemical Philosophy". In this book, he talked about the atomic weight of elements. -
John Dalton talks more about atoms in elements
John Dalton published an appendix to his book "A New System of Chemical Philosophy". In this appendix, he talked more about how "atoms within an element are all exactly the same size and weight" -Bio TrueStory. -
Joseph John Thomson discovers electrons
In 1897, Thomson had discored the electron. He discovered it in a series of experiments that were not meant to find the electron. However, he stumbled upon the electron while studying "the nature of electric disharge in a high vacuum cathode ray tube" according to the "Chemical Heritage Foundation". -
Thomson suggests a theory
"In 1904, Thomson suggested that the model of the atom is a pshere of positive matter while electrons are positioned by electrostatic forces" according to the "Chemical Heritage Foundation". -
Geiger-Marsden Experiment gives amazing results
"In 1907, Hans Geiger, Ernest Marsden and Ernest Rutherford carried out the Geiger-Marsden experiment, an attempt to examine the structures of an atom"-Science Kids. In this experiment, they found out that there was a nucleus in the center of the atom and this became an important part in Rutheford's atomic theory. -
"On a Diffuse Reflection of the a-particle"
In 1909, Hans Geiger and Ernest Marsden spent the year "in the "gloomy cellar" of the physics labratories at Manchester"-"Chemistry Explained". Here, they were watching for "little sparks that announced the unlikely recoil of a-particles"-"Chemistry Explained". About only 1 out of 8000 did and this was put into "On a Diffuse Reflection of the a-particle" that was published in 1909. This result was the base of Rutherford's nuclear model of the atom and the discovery of the proton. -
Ernest Rutherford discovers something
In 1911, Ernest Rutherford found out that the nucleus in an atom is very dense, small and positively charged. -
Rutherford makes a nuclear theory for the atom
In 1912, Ernest Rutherford came up with a nuclear theory for the atom. (In any given atom, "the nucleus occupies a very small volume at the centre". Rutherford had discovered that the nucleus takes up a tiny space in the center of the atom. -
Relation between atomic number and nuclear charge
In 1913, Ernest Marsden and Hans Geiger continued to do research. They eventaully found that atomic numbers are realted to nuclear charges. -
Bohr talks about stable orbits
In 1913, Bohr shared that "his quantized model of the atom" explains that there are electrons that could possibly have stable orbits around the nucleus. This is what we now know as valence electrons. -
Daltons explanation
There is no specific date for this but Dalton was the first scientist to explain that the "behavior of atoms depending on their weight"-Bio TrueStory. He was the first scientist to make any sense about how atoms behave. -
Dalton and atoms
Dalton discovered that atoms couldn't be broken down even more nor could they be created. The date of this discovery isnt known. -
Dalton looks into the atoms of elements
Dalton looked into the atoms of different elements and he found out that each element's atoms were different from one another. -
Discovery from Bohr
In Bohr's time period, he was the first to discover that there were orbits around the nucleus of an atom and that electrons were in these orbits. He also discovered that the number of electrons in these orbits determined the properties of an element. -
Dalton's list of elements
The date that this list was created is unkown but tihs list is really important. This list was for all the atomic weights of known elements of this time period.