Atomic theory

Five atomic models arising from classical and quantum theory through history.

Atoms, the smallest particles of an element that exhibit the properties of that element, consist of negatively charged electrons around a central nucleus composed of more massive positively charged protons and electrically neutral neutrons. Radioactivity is the emission of energetic particles and rays (radiation) by some substances. Three important kinds of radiation are α particles (helium nuclei), β particles (electrons traveling at high speed), and γ rays.

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A brief history of the atom theory

The document traces the historical development of atomic theory, highlighting key figures like Democritus, Dalton, Thomson, Rutherford, Bohr, and Schrödinger. It discusses fundamental concepts of atomic structure, including models from the billiard ball to the quantum mechanical model, emphasizing how atoms interact and combine to form molecules. Additionally, it includes practical activities for visualizing and understanding atomic structure and the scientific method. - Download as a PDF or…

Timeline

Chemistry Topics

A timeline of events about the development of the atomic theory. Consists of 15 scientists who had significant contributions to Quantum Physics.

Dalton's Billiard Ball Atomic Model

Atoms are made up of a nucleus, protons and electrons.

The development of the atomic theory occurred in multiple stages. In 1803, John Dalton put forward the solid sphere model. He stated that atoms are further indivisible, and the atoms of an element are the same. J. J. Thompson modified the theory and proposed the plum pudding model. As per the model, electrons are scattered around in the atom with a cloud of positive charge.

During the classical period, Democritus came up with the atomic theory of matter which states that all things are made up of small spheres called atoms.

Thompson's Plum Pudding Model