Development of The Atomic Model

Who is the first classical atomic theorist?

Democritus

Who believed matter was composed of 4 elements?

Empedocles and Aristotle

Who created the billiard ball model?

John Dalton

Who used sealed glass tubes to generate a glow?

Sir William Crookes

Who created the raisin bun model?

JJ Thomson

Who discovered electrons?

JJ Thompson

Who performed the cathode ray experiments?

Sir William Crookes and JJ Thompson

Who created the beehive model?

Earnest Rutherford

Who performed the Geiger-Marsden experiment?

Rutherford, Geiger, and Marsden

Explain the Geiger-Marsden experiment

• Golf foil surrounded by a circular screen (they chose gold because it can hold its structure while being incredibly thin)

• Reactive radon was placed into a box with a small opening (alpha particle emitter), which was aimed at the gold foil (alpha particles are positive)

• When the experiment was conducted, most of the alpha radiation moved straight through the gold foil, while a few bounced in random directions

  This suggests:

  • atoms are mostly empty space (explains why the alpha ray mostly passed straight through the gold foil)

  • discovered the nucleus (explains why some alpha rays bounced in random directions)

  • electrons in a cloud around the nucleus

• This experiment disproved the raisin bun model and led to the behive model

Who discovered protons?

Goldstein

Who discovered neutrons?

James Chadwick

Who created the planetary model?

Neils Bohr

name all 4 atomic models

billiard ball, raisin bun, beehive, and planetary model