What does an atom look like? We now picture the atom using the Quantum Mechanical model, but there were many other models that led up to our current understanding. In this video. we discuss the History of the Atom and the various early models of atomic structure. The model of the atom has undergone steady changes to reflect experimental results, starting with John Dalton's model (1803), to JJ Thomson's model (1897), to Ernest Ruthford's model (1909), to Niels Bohr's model (1913). Our current atomic model, the "quantum mechanical model," will be discussed in a separate video.
The concept of an atom as the smallest indivisible unit of matter has been around since the ancient Greek philosophers including Democritus (~460-370 BC). But the earliest scientific model of the atom comes to us from John Dalton. Dalton proposed the Atomic Theory in 1803, based on experimental evidence from his studies showing different gases always combined in whole-number ratios.
Since Dalton’s work, the model of the atom has evolved over time to incorporate new experiments and discoveries. This video introduces the following historical models of the atom:
We will continue the story of the atom with the Quantum Mechanical model of the atom, which requires its own video (in production).
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Video: Early Models of the Atom
Handout: Video Notes Worksheet
Practice Test: Atoms, Elements, & Isotopes