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John Dalton
John Dalton had ideas that
* All matter is composed of atoms
* Atombe made or destroyeds cannot
* All atoms of the same element are identical
* Different elements have different types of atoms
* Chemical reactions occur when atoms are rearranged
* Compounds are formed from atoms of the constituent elements. -
Sir Joseph John Thompson (J.J. Thomspon)
Joseph John Thompson Discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube, an area being investigated by numerous scientists at the time. -
Philip Lenard
1902- Lenard showed that an electron must have a certain minimum energy before it could produce ionisation when it passed through a gas
1903- he published his conception of the atom as an assemblage of what he called "dynamides", which were very small and were separated by wide spaces; they had mass and were imagined as electric dipoles connected by two equal charges of contrary sign and their number was equal to the atomic mass. -
Sir Joseph John Thompson (J.J. Thompson)
Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. -
Ernest Rutherford
Ernest Rutherford publishes his atomic theory describing 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. -
Niels Bohr
The timing was very fortuitious since shortly before Bohr and Rutherford met, Rutherford had published a major work showing that the bulk of the mass of an atom resided in the nucleus. -
James Chadwick
James Chadwick proved that the atomic nucleus contained a neutral particle which had been proposed more than a decade earlier by Ernest Rutherford.
