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400 BCE
Democritus
For his experiment, he took a seashell and broke it in half. He took that half and broke it in half again and again until he was left with this fine powder. He couldn't break it. His observation was that atoms are indivisible. Democritus made his model without any protons, neutrons or electrons. It was made to help people have a better understanding of an atom. -
John Dalton
John Dalton decided to compose an experiment. So, he combined 1 atom of hydrogen and 1 atom of oxygen. What he ended up with was 1 compound particle of water. His observations were that Matter is made up of atoms that are indivisible and indestructible and that all elements of an atom are identical. -
Sir J.J. Thomson
Thomson's experiment was to see if atoms are actually composed of aggregates of charged particles. Fortunately for him, it worked and he was able to prove to millions of scientists that atoms are aggregates of charged particles. He also observed electrons in the atoms and spent time studying them. In his model, it shows electrons hidden in the atoms. -
Lord (Ernest) Rutherford
Rutherford used nuclear nature of atoms and deflecting alpha particles passing through a thin gold foil. This was composed to help him as well as other understand the rays of atomic particles. He found out that protons and electrons both pass through the gold foil. -
Niels Bohr
They experimented by creating their model using a positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar to structure of the Solar System. It increased everyone's knowledge of how atoms form. -
Sir James Chadwick
In 1932, the atom was believed to be composed of a positively charged nucleus surrounded by negatively charged electrons. In 1932, James Chadwick bombarded beryllium atoms with alpha particles. An unknown radiation was produced by Sir Chadwick. His model showed us the exact spots and where the protons and electrons were located in atoms. -
Current Model
The current model of an atom, clearly shows what is exactly in an atom. This is due to the amount of extensive research conducted by a lot of scientists.
