History of the Atom

A set of vocabulary flashcards covering the historical models and discovery of subatomic particles as described in the lecture notes.

Dalton's model

Proposed in $1803$, this model described the atom as a solid sphere that cannot be created, destroyed, or divided, and stated that elements were made of different spheres.

Plum Pudding Model

A model proposed by JJ. Thompson where the atom is described not as a solid sphere, but as a cloud of positive charge with negative electrons embedded within it.

Alpha particles scattering experiment

A $1909$ experiment by Rutherford where particles were fired at a sheet of gold foil; most passed straight through, while a few were deflected or returned back.

Nuclear Model

A model proving that the mass of an atom is concentrated in a central nucleus, most of the atom is empty space, and the nucleus must be positively charged to repel Alpha particles.

Bohr Model

A $1920$ model suggesting that electrons orbit the nucleus in shells and that the positive charge of any nucleus is subdivided into smaller particles of equal charge.

Protons

The smaller particles of equal positive charge that the nucleus is subdivided into, according to the Bohr Model.

Neutron Discovery

In $1932$, James Chadwick proved the existence of these particles in the nucleus, which have a neutral charge to maintain the atom's neutral charge.