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Democritus (460 BCE)
He made his discovery in 400 BCE
He thought atoms were invisble, infinite in size & shape, firm and completely solid.
He belived in the smallest possible bit of matter, which he named atoms. -
John Dalton
Dalton discovered in a mixture of non-reacting gases, the total gas pressure is equal to the sum of the partial pressures of the individual gases.
He made this discovery in 1808.
Dalton stated that matter exists in atoms and that atoms of different elements have different masses. -
J.J. Thomson
He discovered electrons.
His model of the atom was called the Plum Pudding Model.
He also discovered that electrons are much smaller than atoms.
He made his discovery in 1904. -
Ernest Rutherford
Rutherford assumed that the entire positive charge of the atom is concentrated in a very small nucleus, and that the electrons occupy the space outside the nucleus.
He made this dicovery in 1911.
His model was named the Rutherford model or Nuclear model.
He also discovered protons in 1919. -
Niels Bohr
Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level to another.
His discovery year was 1913.
He said that electrons were spinning in orbit around the nuclues, -
Heisenberg and Schrodinger (1920s)
They made their discovery in 1927.
They discovered that theres simply just a cloud sourounding the nucleus.
They also stated that no experiment can measure the position and the momentum of a quantum particle simultaneously.
