J.J. Thomson

His model of the atom

Covered in this lesson

• This lesson explains JJ Thomson's experiments that led to the discovery of the electron.

– The discovery of negatively charged electrons smaller than the atom using a cathode ray tube.

Cathode Ray Tube

• A cathode ray tube is a glass tube with most of the air taken out and metal on both ends.

• An electrical current is applied (electron beam)

(diagram wikipedia)

Discovery of the Particles, We Call Electrons

• J.J. Thomson found the beam was deflected by electric and magnetic fields.

• He determined the beam consisted of negatively charged particles smaller than atoms that we now call electrons.

• He found electrons in atoms of various metals and suggested they are found in all atoms.

J. J. Thomson’s Model

J.J. Thomson’s model of the atom consists of a sphere filled with a positively charged cloud containing negative particles (electrons) spread throughout the cloud.

(diagram wikipedia)