HISTORY OF THE ATOM
First, finish your timeline!
Then let's get into the details.
Ok, so the atom has been around forever. Humans have just noticed them recently! It's still really helpful to see how science changes and evolves based on more information, knowledge and better tools.
Let's take a ride through the past and see how these ideas changed and evolved!
Let's take a ride through the past and see how these ideas changed and evolved!
Atomus - By Democritus, 2500 B.C.
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Democritus had a big imagination. He managed to come up with this theory of Atomus before there was any way to prove it!
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His theory stated that atoms were tiny, uncuttable, solid particles that are surrounded by empty space and constantly moving at random.
Four Elements - by Aristotle, 400 B.C.
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Aristotle was a really well-known guy. He was also a philosopher, so... bro could talk, and I mean TALK. So, when he showed up and said Aristotle was just an old fool, and that everything was just made of the four elements, people lapped it up like it was mango lassi.
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Except that he should probably have stuck to his theories, because he was dead wrong; and since he was so famous, he reeeeeally messed up science for another 2000 years.
1. Democritus (c. 460–370 BCE)
7. Albert Einstein (1905)
- Model/Idea: The first "Atomos" (indivisible) concept.
- Summary: As an ancient Greek philosopher, he proposed that matter could not be divided infinitely. Eventually, you would reach a tiny, hard, indestructible particle, which he called atomos. He believed these particles differed in shape and size.
- Model/Idea: The "Continuity" Model (4 Elements).
- Summary: Aristotle rejected Democritus's idea, arguing that matter was continuous (not made of atoms) and infinitely divisible. He proposed that all matter was composed of four elements: earth, fire, air, and water. Due to his influence, this view held for over 2,000 years.
- Model/Idea: The "Billiard Ball" Model.
- Summary: Dalton revived the atomic concept based on experimental evidence. He proposed that all matter is made of tiny, indivisible atoms, that atoms of the same element are identical in mass, and that compounds are formed by combinations of different atoms.
- Model/Idea: The "Plum Pudding" Model.
- Summary: By discovering the electron using cathode rays, Thomson proved atoms were divisible. He proposed that an atom was a positively charged sphere (the "pudding") with negatively charged electrons (the "plums") embedded within it.
- Model/Idea: The "Nuclear" Model.
- Summary: Through his famous gold foil experiment, Rutherford discovered that the atom is mostly empty space with a tiny, dense, positively charged nucleus at its center. He proposed that electrons orbit this nucleus.
- Model/Idea: The "Planetary" Model.
- Summary: Bohr improved Rutherford's model by proposing that electrons move in specific, quantized orbits or shells at fixed energy levels around the nucleus, rather than just randomly orbiting.
7. Albert Einstein (1905)
- Contribution: Evidence for Atomic Existence.
- Summary: While not proposing a model of the inside of the atom, Einstein provided the theoretical, mathematical proof of the existence of atoms by analyzing Brownian motion (the random movement of particles in a fluid). His work provided the "smoking gun" that proved atoms actually existed.
- Model/Idea: Matrix Mechanics / Uncertainty Principle.
- Summary: Heisenberg contributed to the development of quantum mechanics by proposing the uncertainty principle, which states that it is impossible to know both the exact position and momentum of an electron simultaneously. This helped shift the focus from fixed orbits to probability.
- Model/Idea: The "Quantum Mechanical" (Electron Cloud) Model.
- Summary: Schrödinger treated electrons as waves rather than particles, developing a wave equation to describe the likelihood of finding an electron in a certain position. This model replaced orbits with orbitals—3D clouds of probability where electrons are likely to be found.
