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1803 BCE
Democritus Model
atomic model was solid, and stated all atoms differ in size, shape, mass, position and arrangement, with a void exists between them. -
1766 BCE
John Dalton
The atom for them looked like a solid sphere, model or bowling ball model. -
460 BCE
Democritus
atoms are "uncuttable"
atoms are small, hard particles
atoms constantly move -
John Dalton
all substances are made of atoms
atoms of different elements are different
atoms of the same element are exactly alike
elements combine in specific proportions
conducted experiments in combining elements -
J.J Thomson
He conducted the cathode-ray tube experiment
His theory of the atomic structure lead to the "plum-pudding" model
There are small, negatively charged particles inside an atom -
Ernest Rutherford
atoms contain mostly empty space
Electrons move in empty space in the atom
he conducted the gold foil experiment
most of an atom's mass is in the nucleus
there is a small, dense, positively charged nucleus -
Ernest Rutherford
atom is mostly empty space, with electrons orbiting a fixed, positively charged nucleus in set, predictable paths. -
Neils Bohr
Electrons jump between levels from path to path
Electrons travel in definite paths -
J.J Thomson Model
the atom is a sphere of positive charge, and negatively charged electrons are embedded in it to balance the total positive charge. -
Erwin Schrodinger and Werner Heisenberg Model
model is patterned on the solar system and is known as the planetary model. -
Niels Bohr Model
Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted. -
Erwin Schrodinger and Werner Heisenberg
Electrons are found in electron clouds, not paths
Electron path cannot be predicted
