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Democritus
The Democritus Atomic Theory revolves around the atoms that are present in the atmosphere like the atoms that are here that existence like a solid or liquid. The theory says that these atoms are all individually created and cannot be separated, no matter what. -
John Dalton
All matter is made of atoms. Atoms are indivisible and indestructible.All atoms of a given element are identical in mass and properties
Compounds are formed by a combination of two or more different kinds of atoms.
A chemical reaction is a rearrangement of atoms. -
J.J. Thomson
He used a sealed tube of gas in his ezperiment. when the current is on, the disks becames charges and a glowing beam appeared in the tube. The beem bent torward a positicely charges plate placed outside the tube.
His experiments provided the first evidence that atoms are made of even smaller particals. -
Hantaro Nagaoka
Nagaoka rejected Thomson's model on the ground that opposite charges are impenetrable. He proposed an alternative model in which a positively charged center is surrounded by a number of revolving electrons, in the manner of Saturn and its rings. -
Ernest Rutherford
The atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space.
Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected leading him to his theory that most of the atom was made up of 'empty space'. -
Neils Bohr
Bohr found that the closer an electron is to the nucleus, the less energy it needs, but the farther away it is, the more energy it needs. So Bohr numbered the electron’s energy levels. The higher the energy-level number, the farther away the electron is from the nucleus — and the higher the energy. -
Werner Heisenberg & Erwin Schrodinger
Erwin Schrödinger and Werner Heisenberg discovered the electron cloud model. They said an atom consists of a dense nucleus and many proton and neutrons and is surrounded by electrons, but they all have different energy levels, and different charges. -
James Chadwick
James Chadwick proved the existence of neutrons in 1932. As uncharged particles in atoms, neutrons play a key part in nuclear fission, or the splitting of atoms.
