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500 BCE
Democritus
Democritus was a student of a famous Greek Philosopher Leucippus. He first proposed the idea that all matter is composed of small indivisible particles. He believed that atoms of an element were different, but also the same. Also that substances have different characteristics from the atom's shape. -
Christiaan Huygens
He created the wave theory of light. He believed that light was made up of waves and these waves vibrated in the way light traveled. His theory determined the true shape of saturn's rings, and also it's moon. -
Isaac Newton
He studied gas and the possibility of atoms actually existing. He believed that they were small bits of mass that could be swimming everywhere, atoms and particles do move around. -
John Dalton
Dalton's theory has greatly influenced the modern atomic theory of today. He said that all matter is composed of atoms, tiny, indivisible particles that cannot be created or destroyed. Atoms from different elements can combine to create compounds, and atoms change during chemical reactions. -
Gustav Kirchhoff
He discovered 2 alkali metals with a device spectroscope. This discovery opened up a new way to find elements and to fill the holes that were missing. -
James Maxwell
He studied the connection between 2 forces which proved that electromagnetic waves are real. He conducted these experiments using the velocity of light and electromagnetic fields. -
Heinrich Hertz
He was the first one to prove the existence of electromagnetic waves, based off of Maxwell's theory of light. He is most known for the discovery of electromagnetic radiation. Which refers to the waves of the electromagnetic field that carry radiant energy. -
J.J Thomson
Thompson conducted the first experiments to determine the mass of an electron using the Cathode Ray Tube. He created his own visual of what an atom looks like, comparing it to plum pudding. He also said that atoms need to have a positively charged particle to neutralize negative charges from the electrons. -
J.J Thomson's Plum Pudding Model
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Ernest Rutherford
Rutherford studied radiation and used gamma rays to conduct his experiments. He proved that the nucleus of the atom was positive by shooting alpha particles at a sheet of gold foil and watched which particles passed through, and which ones were deflected. -
The Rutherford Model
This model shows electrons orbiting the nucleus. -
Albert Einstein
Albert Einstein created a formula to mathematically prove that atoms exist. This commonly heard formula is E=mc^2 and he also wrote a paper on Brownian Motion which helped strengthen the atomic theory. -
Max Planck
He was the originator of the quantum theory. He has won many prizes for his theory and discoveries including the Nobel Prize in 1918. His theory reinvented the way humans understand atoms and subatomic particles. -
Bohr Model
In this model you can see the nucleus is in the centre of the atom while the electrons orbit around in their shells. -
Neils Bohr
He theorized that the chemical properties and identity of the atom depended on the amount of electrons. He also introduced the idea that electrons can leap to and from different orbitals within the atom.
