The History of Atomic Theory

Contributor: Meghan Vestal. Lesson ID: 11156

Atoms are really tiny. Does something that small matter? Yes, because everything is made of matter: gazillions of atoms hanging together. Discover how they were discovered and present your findings!



learning style
personality style
Lion, Beaver
Grade Level
Middle School (6-8)
Lesson Type
Dig Deeper

Lesson Plan - Get It!


Today, it is commonly accepted that all matter is made up of tiny particles. Who discovered these particles? And, if these particles are so tiny, how were they discovered?

Atomic theory is a scientific theory that states that all matter is made of tiny particles called atoms.

Everything, including the air we breathe, is considered to be matter. That means atomic theory impacts just about everyone and everything on Earth! Some scientists even claim atomic theory is the most important scientific development ever!

Atomic theory cannot be credited to just one person. It was developed over hundreds of years by several scientists.

In this lesson, you will investigate the roles of Democritus, John Dalton, J.J. Thompson, Ernest Rutherford, and Niels Bohr in developing atomic theory. If you are unsure of exactly what an atom is, it may be a good idea to complete the series "All About Atoms" before moving forward in this lesson.

Copy the following chart onto a separate piece of paper. As you watch the video and read the articles, complete the chart:


Years Alive


Contributions to Atomic Theory

Are His Ideas Still Accepted Today?



John Dalton


J.J. Thompson


Ernest Rutherford


Niels Bohr



Get ready to explore the microscopic world of atoms, and find out how they came into focus as the basis of all matter, as you watch TEDEd's video, The 2,400-year search for the atom- Theresa Doud, to learn more about the history of atomic theory.


Then, visit each of the following sites to continue learning:

Review the chart you created with a teacher or parent.

  • Which discovery did you find the most interesting?

Move on to the Got It? section for a bit of a quiz.

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