The early development of the atomic theory first started with the ancient Greeks. The ancient Greeks had come to a conclusion that there was only 4 elements on Earth: air, wind, water, and fire (however, none of these elements exist today on the Periodic Table of Elements).
Specifically, around 400 B.C.E. Greek philosopher, Democritus, stated that everything is made of small, unbreakable units, called atoms that are all solid. Coming from the Greek word, "atomos," means indivisible or uncuttable. Even though, Democritus never developed a model, his idea for atoms is used as a basis for the atomic theory. And no one made any significant changes for hundreds of years. |
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The Current model of the atom is called the Quantum Mechanical Model or the Electron Cloud Model, and much like the last two models.
- It has electrons that orbit the positively charged nucleus, however they are not in a definite rotation.
- Neutrons and Protons are present in the nucleus
- Electron are located in an area referred to as the electron cloud