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500 BCE
Democritus Theory
He came up with the idea that everything was made up of tiny particles which he called atomos which meant "unable to cut". -
500 BCE
Heraclitus Theory
This philosopher came up with the belief that everything was made up of fire. -
350 BCE
Aristotle Theory
Aristotle believer that all matter was made up of four elements, water, air, fire, and earth. He was a very popular philosopher which made his theory the most popular. -
John Dalton Theory
Dalton's main ideas were:
1. All matter is made up of very tiny particles called atoms.
2. All atoms of a given element are the same in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
3. Atoms cannot be created or destroyed; they are invisible.
4. Different elements combine in simple whole-number ratios to form chemical compound.
5. Chemical reactions make atoms combine, separate, and rearrange. -
J.J. Thomson Thory
Thomson discovered electrons. Thomson also came up with an idea of using a model to showcase how the electrons and positively charged matter would counter balance each other. And this model was called the plum pudding model. This was a very important find because if helped to shape how to draw bor models that we see now a days. -
Ernest Rutherford's Discovery
Ernest created an experiment in which he aimed a beam of alpha particles at a thin sheet of gold foil. Outside the foil, he placed a screen of material glowing when alpha particles struck it. If Thomson’s plum pudding model was correct, the particles should be deflected a little while passing through the foil. Most passed through the foil while others bounced back leading him to believe something there was nucleus. Later discovering protons. He thought that electrons randomly orbit the nucleus.