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Democritus 460BC
Democritus was a philosopher who lived in ancient Greece from 460BC to 370BC.Democritus stated that everything is made up of atoms. He said atoms are physically indivisible and atoms are between empty spaces. Atoms are indestructible and atoms differ in shape and size. -
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Aristole 384BC
Aristole was an ancient Greek Philosopher who lived in Stagira, Greece from 384BC to 322BC.He did not get how atoms could stay in a never changing motion so he developed a theory. Aristotle’s theory was based on the idea that all matter is made up of the four elements Fire, water, earth, air. He believed that the elements could have four certain qualities: Wetness, hotness, coldness and moistness. -
Robert Boyle 1697
Robert Boyle was born in Ireland in 1627. He wrote a book called the “Sceptical Chemist” which said chemist should abandon the thought the elements are mystical substances. He said that the term elements needed a precise meaning. He said an element is not capable of being broken down into a more simple substance. He also believe that everything was made up of particles. -
Issac Newton 1704
Isaac Newton proposed in 1704 there were small solid masses moving. Simplified he believed that tiny particles where swimming everywhere. -
John Dalton 1803
During 1803 John Dalton discovered that only certain gases could be combined in certain proportion even if they shared common elements or groups of elements. He also discovered elements consist of particles called atoms. Atoms of an element are all the same for that element. He also stated that atoms can be told apart by their atomic weight and that atoms cannot be destroyed or created in chemical reactions. The grouping of the atom only changes -
Dmitri Mendeleev 1860
During the 1860s Dmitri Mendeleev began to make the periodic table of elements. By fitting in all of the 63 elements he soon realised there were gaps which meant there were more elements to be found. -
G.J Stoney
During 1874 stoney’s proposed the a calculation for the magnitude of the atom or particle oof electricity. He also estimated home many molecules where in a cubic millimetre of gas. -
J.J Thomson 1897
Thomson actually discovered the electron in 1897. He also proposed a new theory. That the atom is made up of small particles. -
James Clerk Maxwell 1900
In the 1900s Maxwell Proposed electric and magnetic fields filled the void. Which means that the atom has electronic charges inside it -
Albert Einstien 1905
In 1905 Einstein added three papers to the annals of physics. In these papers he writes about how mass- energy equivalence through e=mc2. He also stated that movement in molecules in a liquid could cause the Brownian motion. -
Robert Millikan 1909
In 1909 with his oil drop experiment Robert Millikan determined the unit charge of an electron. This allowed the calculation mass of an electron. -
Ernest Rutherford 1911
During the year 1911 Ernest Rutherford published his atomic theory. He described the atom saying that it has a central positive nucleus which is surrounded by orbiting electrons. This idea suggested that most of the mass of the atom was contained in the tiny nucleus and the rest of the atom was just space. -
Frederick Soddy 1912
Frederick Soddy proposed in 1912 that same elements exist in different forms with nucleus still having the same amount of protons but the electrons surrounding where a different amount. This was his theory of isotopes explains that atoms can be hardly indistinguishable but they have different atomic weights and characteristics. -
Niels Bohr 1913
In 1913 Niels bohr applied the quantum theory to Rutherford’s atomic structure. He said that electrons travel in a stationary orbit. This led the calculation of possible energy levels -
Werner Heisenberg 1958
In 1958 Werner contributed to the atomic theory by calculating the behaviour of electrons, and the subatomic particles that make up the atom
