• atoms - matter's fundamental building blocks
• this notion began at around 440 B.C. and over the years, it has changed and develop
• ancient philosophers like Leucippus and Democritus, for instance, though that atoms were particles that are solid and of different sizes and shapes.
• in 1911, Ernest Rutherford proved that an atom was largely empty space
• experiments like firing tiny pieces of matter at atoms or heating substances in a flame helped scientists learn more about an atom's structure and their behavior
• Natural philosophers did not prove or disprove theories using experiments during ancient times (around 440 BC)
  • to prove their ideas or beliefs to be true, they used sound arguments

Leucippus

<aside> 🍁 - proposed the idea that "all things are basically made up of atoms which are indivisible"

• he did not have enough evidence since they do not conduct experiments therefore was not able to persuade a number of philosophers
• philosophers who agreed with him are called "atomists"

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Democritus

<aside> 🍁 - a student of Leucippus

• one of the first atomists

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Epicurus

<aside> 🍁 - improved the atom idea

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• Imagine breaking an object in half, and then breaking it in half again and again. (a) How many times can you do this? (b) Can you keep going, getting even smaller? The answer of atomists to 'b' is no.
• They believed that all matter has these small particles which are called atoms that can be divided until its pieces cannot be split into smaller particles anymore.

Dalton's Atomic Theory

Law of Conservation of Mass

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Law of Definite Proportions

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