History of the Development of the Modern Model of the Atom

Dalton’s Atomic Theory (early 1800’s)

What did Dalton think the atom looked like?

Dalton was not quite correct.

Thomson and the Cathode Ray Tube (late 1800’s) Thomson concluded that the atom was made of ____________________. Discovered particles with __________ __________________ No matter what metals were used they all produced a negative beam of light Therefore ____________________________ _____________________________________

Thomson theorized a new model of the atom.

Rutherford’s Gold Foil Experiment

OBSERVATIONS CONCLUSIONS

Rutherford’s Model Electrons randomly orbit a large, positive nucleus

Bohr Model of the Atom (early 1900’s) Electrons have __________ ______________orbits Electrons have a _____________ orbits farther from the nucleus have greater energy

Electron-cloud model Modern Model electrons are most likely found in regions outside the nucleus called _________ and do _______ ______________________ ________________________________

orbital shapes

THE END