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Democitus (460-360 B.C)
A philospher and scientist who was one of the first people who had an idea that all mater was made up of tiny parts that could not be divided or destroyed. He had the first idea for atoms. A greekword named atomos meaning "indivisible". However later scientist found out that atoms were able to be broken down and were made up of smaller subatomic particles. -
Period: to
Atomic Timeline
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Lavoiser
DIscovered the conservation of mass. Considered to be the father of modern chemistry. Born in france in the 25th of August 1743 and died on 8th of May 1794 -
Law of conservation of mass
Made by Antoine Lavaoisier. This law states that mass is neither created or destroyed in chemical reactions. Meaning that at the beginning and end of a reaction, the mass of any element is the same at those times. This also means that atom can neither be destroyed or created by a chemical reactions as well. -
Joeseph Proust
Joseph L. Proust was born on September 26, 1754 in Angers, France. Had a contreversial arguement with another scientist named C.L. Berthollet. Proust was a teacher who made the "Law of definite proportions". -
French Revolution
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Spherical Model
All atoms are one sphere that cannot be broken down. Was changed due to the findings of other subatomic particles and isotopes. -
John Dalton
John Dalton was born on the 6th of september, 1776 in eaglesford,cumberland, england. John dalton discovered the idea of atomic theory and the spherical atomic model of the atom. John dalton also was the first person to link elements to atoms. -
Law of definite proportions
Dissapproved Berthollet with the creation of the law of definite proportions. The laws tates that a chemical compound always contains exactly the same proportion of elements by mass. Berthollet argued that any element can combine into any proportions but this law debated against his sayings. Prousts Law was placed on knowledge gained from atomic theory by John Dalton. -
J.J Thomson
Born 18 December 1856 – 30 August 1940.Discovered electrons by using an experiment with the cathode ray tube. Proved electrons by proving that cathode rays had a negatively charged particles which he then named "Electrons". Thomson later created a new model of the atom named "Plum-Pudding" model. -
Plum Pudding model
Atoms are solid spheres made-up of a solid positive mass (or core) with tiny negative particles embedded in the positive core.
Did not show electrons outside of atom and did not show neutrons after the discovery of the isotopes of atoms therefore changed later on. -
Robert Millikan
Discovered charge and mass of electrons by using his oil drop experiment. -
Rutherfords Model (Planetary Model)
Proved by rutherfords famous gold leaf experiment. Proves that electrons orbit around the nucleus and that the nucleus is positively charged. Was changed due to the fact that there was no inclusion of neutrons. -
Ernest Rutherford
Born August 30 1871 in Brightwater New Zealand.
Discovered Nuclear Model of the atom and the proton. Founded Nuclear Model in 1911 and proton in 1920.
Worked with other scientist such as Hans Geigar and J.J Thompson in Cambridge.
Famous Experiment he worked on was the gold foil experiment. -
Discovery of the Nucleus
Rutherford concluded that the nucleus is a small mostly empty space and was dense and postively charged, however his ideas was rejected because he had no tangible proof of a nucleus in an atom. -
Neils Bohr
A Danish physicist who stated that electrons could only orbit the nucleus in succesively larger orbits around the nucleus. The outer orbits could hold more electrons. The electrons in the outermost shell determine the properties of the atom. His atomic model was named the "Nuclear Model" as he states electrons could only orbit around the nucleus. Bohr collabrated with other physiscist such as Heisenberg and Klein. -
Louis De Brogeille
Proposed that moving particles are like electrons and that they have properties of waves. His ideas were proven after few years of experiments -
Heisenberg's uncertainty priniciple
(5 December 1901 – 1 February 1976) was a german physicist who was one of the key collaborators on quantum mechanics. He also published the uncertainty priniciple in 1927. -
The uncertainty priniciple
Published by Wern Heisenberg in 1927, states thatThe position and momentum of a particle cannot be simultaneously measured with arbitrarily high precision. There is a minimum for the product of the uncertainties of these two measurements. Part of quantum mechanics. -
Ernest Schrodinger
Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom. Ideas collaborated with other scientist to make the quantum mechainical model. He discovered the electron cloud which is one of the reasons why nuclear model of the atom had to change. -
James chadwick
Chadwick worked as an undertstudy to Rutherford who founded the proton in 1920. However, Chadwick Discovered neutron by researching and using alpha particles. Chadwick kept seeing that the atomic mass was not equal to the mass of an atom therefore there must be another particle in the nucleus. He later used alpha particles to find a new subatomic particle which had an equivalent mass to the proton naming it the neutron as it had no charge. -
Hiroshima and nagasaki
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J.Robert Oppenheimer
Known for working on the atomic bomb. Studied under Rutherford in 1925. Most of his analysis predicted future finds such as the neutron, positron, meson, and neutron stars. Oppenheimer was the head of the Mannhattan Project and by July 1945 he witnessed the first atomic bomb to be dropped in New Mexico. He also helped create the even more powerful Hydrogen bomb as well but was kicked off due to him being sympathetic to communists.
"Science is not everything, but science is very beautiful."
