Atomic Structure and Subatomic Particles

Vocabulary-style flashcards covering the history and discovery of subatomic particles, including cathode rays, electrons, and protons, as well as the scientists and experiments involved.

Molecules

Particles which show all the properties of the substance and have a free existence.

Subatomic particles

Particles smaller than atoms, such as electrons, protons, and neutrons.

William Crookes

The physicist who in 1875 conducted experiments by passing electricity at high voltage through a glass discharge tube.

Anode

The positive electrode in a discharge tube.

Cathode

The negative electrode in a discharge tube from which rays are emitted.

Cathode rays

Rays emitted from the cathode that travel in straight lines, have mass, and are attracted toward the positive side in an electric field.

Henrich Giesler

A scientist who developed discharge tubes and suction pumps in 1854.

Julius Plucker

A scientist who found that electricity passing through a tube forms a glow whose position can be changed in the presence of a magnet.

Electrons

Negatively charged subatomic particles that are present in all substances, discovered through studies of cathode rays.

J. J. Thomson

The scientist who determined the ratio of electrical charge to mass (e/m ratio) of an electron and won the Nobel Prize in 1906.

$e/m$ ratio of an electron

The ratio of electrical charge to mass of an electron, determined by J. J. Thomson to be $1.76 \times 10^{11}\,C/kg$.

Robert Millikan

The scientist who, through his oil drop experiment, found the specific charge of an electron and calculated its mass.

Charge of an electron

$1.6 \times 10^{-19}\,C$ (negative charge).

Mass of an electron

$9.1 \times 10^{-31}\,kg$.

Canal rays

Also known as Anode rays, these are positively charged rays discovered by Eugen Goldstein in 1886 using a perforated cathode.

Proton

The name given by Earnest Rutherford to the smallest and lightest positive subatomic particles obtained when a discharge tube is filled with hydrogen.