Democritus (Greek Philosopher) Timeline: 400BCHe was the first person to use the term atom (Atomos: meaning indivisible).
He thought that if you take a piece of matter and divide it and continue dividing it will eventually come to a point where you could not divide it any more.This fundamental or basic unit was what Democritus called an atom He called this as the theory the universe
1. All matter consists of atoms, which are bits of matter to small to be seen
2. Each atom (of a different substance) is different in size, weight and shape
JOHN DALTON. Time line: 1800He was the first to adapt Democritus theory into the first modern atomic model.
1. All matter consists of tiny particles called atmos.
2. Atoms are indestructible and unchangeable.
3. Elements are characterized by the weight of their atoms.
4. When elements react, it is their atoms that have combined to from new compounds.
J.J.THOMSON. Time line: 1890He was a physicist who is creadited for discovering the electron. He used his research on cathode ray tube technology in this discovery.
1. An electric charge is passed through the tube. Travels from cathode to anode
2. The charge is invisible, so to see where it traveled a fluorescent screens is placed at back of tube will light up.
3. Thompson showed (as in the diagram above) that the charge would deflect away from the negative coil. He then stated that this charge was thus a negative charge.
THOMSON´S ATOMIC MODELUsing what he had dicovered, Thomson predected what an atom should look like. These are the key points to Thomson´s Atomic Model:
1. Because of its design, this model was known as the plum pudding model,
2. Each atom is a sphere filled with positively charged "fluid". This resembles the sticky jam part of a pudding.
3. Corpuscles (later called electrons), are the negatively charged particles suspended in this "fluid" resembles the plums in the pudding.
ERNEST RUTHERFORD. Time line: 1910He was not convinced about the model of the atom proposed by Thomson. He thus set up his now famous GOLD FAIL Experiment
1. He fired alpha particles (positively charged) at a gold foil.
2. He measured the deflection as the particles came out the other side.
3. Most of the particles did not deflect at all. Every now and then, a particle would deflect all the way back.
4. He said that there must be a positive center of the foil. He called this center NUCLEUS.
RUTHERFORD´S ATOMIC MODEL-AKA PLANETARY MODEL
NIELS BOHR.Time line:1910He was agreed whit the planetary model of the atom but aslo knew that is has few flows, using his knowledge of energy and quantum physics he was able to perfect Rutherford´s model. He was able to answer why the electrons did no collapse into the nucleus.
BOHR´S ATOMIC MODEL (AKA THE RUTHERFORD-BOHR MODEL)
ERWIN ESCHRODINGER. Time line: 1920He was a revolutionary physicist who use Heisenberg´s uncertainty principle to come up with the atomic model that we still use today.
1. An electron doesn´t travel in a specific orbit
2. We can predict where it will probably be.
3. We cannot say for certain where it is, but where ought to be.
4. The type of probability orbit is dependent on the energy level by Bohr.