5 Questions
Which scientist modified an earlier theory that matter was made of four elements: earth, fire, water, air?
Aristotle
Who was the first to adapt Democritus’ theory into the first modern atomic model?
John Dalton
Who was the first person to use the term 'atom' (atomos: meaning indivisible)?
Democritus
Which physicist is credited for discovering the electron?
J.J. Thomson
What did Democritus believe about the fundamental unit of matter?
It was indivisible and called an atom.
Study Notes
Atomic Theory
- A scientist modified the earlier theory that matter was made of four elements: earth, fire, water, air.
Democritus' Contribution
- Democritus was the first to propose that matter is composed of tiny indivisible particles called atoms (atomos: meaning indivisible).
- Democritus believed that the fundamental unit of matter was the atom, which was eternal, indivisible, and indestructible.
Development of Atomic Model
- The first modern atomic model was adapted from Democritus' theory.
Discovery of the Electron
- J.J. Thomson is credited with discovering the electron.
Test your knowledge of the history of atomic theory with this timeline quiz. Learn about the contributions of early scientists such as Democritus and Aristotle to the development of the concept of atoms.
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