J.J. THOMSON

PERSONAL INFO

• Born Joseph John Thomson on Dec. 18, 1856
• Hometown is Cheetham Hill, Manchester, England
• Educated at University of Manchester, then later at Cambridge University

CONTRIBUTING EXPERIMENTS

• Thomson performed most of his experiments with cathode rays
• These rays are streams of electrons observed in vacuum tubes.
• It was under debate at the time whether cathode rays has mass and were
• composed of particles, or were immaterial like light.
• By working extensively with the rays, Thomson was able to discover much about them.

CONTRIBUTING EXPERIMENTS

• He concluded that the rays were composed of very light,
• negatively charged particles which were a universal building block
• of atoms. He estimated the mass of these rays by measuring the heat
• generated when the rays hit a thermal junction and comparing this
• with the magnetic deflection of the rays.

CONTRIBUTING EXPERIMENTS

• By finding this, Thomson had just discovered the electron.
• He then went on to prove many other properties of electrons,
• such as how they could be deflected electrically, their mass-
• to-charge ratio, and even how many electrons composed a set element.
• All this was accomplished by his use of cathode rays.

CONTRIBUTIONS TO TODAY

• J.J. Thomson was the first person to suggest the theory of the atom containing
• positive and negative particles, and demonstrated the latter, which he called "corpuscles"
• He proved the the hydrogen atom has only one electron.
• Stated and defined numerous properties of electrons.
• Improved the overall knowledge of the atom by experimenting with cathode rays.

THOMSON VS. DEMOCRITUS

• Thomson updated Democritus' model of the atom by adding
• the previously unknown electrons. Thomson depicted this as a smooth
• sphere with other small spheres suspended around it.
• This model came to be known as the "plum-pudding" model, due to its looks.

THOMSON VS. DEMOCRITUS

• Thomson largely focused on the specifics of atom, such as measureable
• qualities and properties. Democritus, limited by the technology of his time, studied the question
• "Can matter be split an infinite number of times?" Based on this, Democritus defined the atom
• and began the basis of knowledge of the atom, of which Thomson added to and
• improved upon, continuing his legacy and establishing one of his own.