scientists

thought all objects were product of four elements which are fire, air, water, earth

• Aristotle

• John Dalton

• Ernest Rutherfold

• JJ Thompso

presented that matter is made of very small particles called ATOMS - building block of matter, divisible

• John Dalton

• Aristotle

• JJ Thompson

• Ernest Rutherfold

discovered electron 1897 - Cathode Ray Experiment. He also discovered isotopes in 1913.

• JJ Thompson

• Aristotle

• John Dalton

• Niels Bohr

He coined the word “Proton” for the smallest unit of positive charge in the nucleus. Nucleus Theory, alpha particle gold foil experiment. His model states that “All of an atom’s positive charge is concentrated in its nucleus”.

• Ernest Rutherfold

• John Dalton

• Aristotle

• JJ Thompson

Planetary Model 1913. Nucleus surrounded by orbiting electrons at different energy levels. Electrons have definite orbits.

• Niels Bohr

• Aristotle

• James Chadwick

• Werner Heisenberg

Quantum Mechanical Model 1926, developed quantum numbers based on theories of einstein and planck

• Louis De Brogile, Ernst Schrodinger, Werner Heisenberg

• Aristotle, John Dalton, JJ Thompson

He discovered Neutrons. Neutral particle with mass close to proton

• James Chadwick

• Eugene Goldstein

• JJ Thompson

Who discovered Proton

• Eugene Goldstein

• James Chadwick

• JJ Thompson

Who discovered Electron

• JJ Thompson

• Eugene Goldstein

• James Chadwick

German chemist who formed the triads of elements.

• Johann Wolfgang Dobereiner

• John Newlands

• Dmitri Mendeleev

• Lothar Meyer