Atomo Timeline

Democritus:

His theory: Matter could not be divided into smaller and smaller pieces forever, eventually the smallest possible piece would be obtained. This piece would be indivisible. He named thesmallest piece of matter “atomos,” meaning “not to be cut.”
To Democritus, atoms were small, hard particles that were all made of the same material but were different shapes and sizes. Atoms wereinfinite in number, always moving and capable of joining together.

Dalton:

He proposed the Atomic theory of matter based on his experimental observations.
-All matter is made of atoms. Atoms areindivisible 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 chemicalreaction is a rearrangement of atoms.
-Atoms can be neither created nor destroyed.

Thomson:

Thomson's atomic theory proposed a model of atom which is known as plum pudding model
In the year 1897Joseph John Thomson totally changed the view of an atom by discovering electron. Thomson’s atomic theory suggested that the atom is not indivisible as it was of smaller pieces – electrons and protons.-An atom consists of a sphere of positive charge with negatively charged electron embedded in it.
-The positive and the negative charges in an atom are equal in magnitude, due to which an atom iselectrically neutral. It has no over all negative or positive charge.

Rutherford

On 1911, Ernest Rutherford presented a paper to the Manchester Literary and Philosophical Society accuratelydescribing the structure of the atom. Based on an experiment he had performed - with totally unexpected results - he realized that the atom must have almost all of its mass concentrated at its center, ina nucleus, with the vast majority of the atom consisting chiefly of empty space.

Bohr:

Neils Bohr refined Rutherford's model in 1913 by proposing that electrons:
-orbit the nucleus without...