Atomic Models Flashcards

Flashcards about atomic models for 8th grade science review.

Dalton’s Model (1803)

Dalton's Model said that all matter is composed of atoms, which are indivisible and solid spheres. Introduced the idea that atoms of a given element are identical in mass and properties, while atoms of different elements differ in mass. Established the concept of the atom as the fundamental unit of matter.

Thomson’s Model (1897)

Thomson's Model, also known as the Plum Pudding Model, was proposed in 1897 by J.J. Thomson. It showed atoms as a positively charged sphere with negatively charged electrons scattered throughout. This model was based on his experiments with cathode rays, which led to the discovery of the electron. Refuted by Rutherford's gold foil experiment, confirmed the existence of a dense nucleus.

Rutherford’s Model (1911)

Rutherford’s Model created in 1911 he postulated that atoms consist of a positively charged nucleus surrounded by a mostly empty space where electrons travel in orbit. The model was based on the results of the gold foil experiment; some alpha particles were significantly deflected which led Rutherford to conclude that the positive charge and majority of the mass of the atom are concentrated in a small nucleus.

Bohr’s Model (1913)

Bohr's Model, proposed in 1913 by Niels Bohr, introduced the idea that electrons travel in specific orbitals around the nucleus and that these orbits correspond to discrete energy levels. This model addressed the limitations of Rutherford's model by incorporating quantum theory, explaining how electrons could occupy stable orbits without radiating energy and orbiting into the nucleus.

Quantum Mechanical Model (Modern)

The Quantum Mechanical Model is the current understanding of atomic structure describing electron location in orbitals around the nucleus. It incorporates wave-particle duality and the Schrödinger equation, predicting chemical behavior and properties with consideration for the uncertainty principle. Shows the probabilities of finding electrons in various regions rather than fixed paths (shows them in clouds).