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Democritus
He developed the basic understanding of atoms ad how matter is made up of tiny, hard, indestructable particles called atoms. -
Antoine Lavoisier
Lavoisier was the first person to isolate and name the element, oxygen. Often refferred to as the "Father of Modern Chemistry". -
John Dalton
Dalton suggested a new way to distinguish between elements and compounds and he created the "Dalton's Atomic Theory". -
Dalton's Atomic Theory
John Dalton invented an atomivc theory that helps distinguish between elements and compounds. The theory consisted of 4 points that we learned of, but it most importantly stated that different elements are made up of different atoms. -
Dmitri Mendeleev
Mendeleev organized the known elements based of properties like in order of increasing atomic mass, which then formed the periodic table. -
Cathode Ray Tube
Joseph John Thompson proved that rays radiating ffrom negatively charged cathodes were made up of what we call "electrons", which are negatively charged particles that are found inside atoms. -
Plum Pudding Atomic Model
J.J. Thompson came up with an atomic model called "plum pudding", which consisted of negatively charged atoms within a mass of positively charged material. -
J.J. Thomson
Thompson proved the Cathode Ray Tube and invented the atomic model, Plum Pudding. -
Robert Millikan
His biggest achievemnt was finding the accurate determination of the charge carried by an electron. He used the "Falling-Drop Method" to prove the quantity was a constant for all electrons. -
Gold Foil Experiment
Ernest Rutherford discovered the nucleus by shooting positively charged alpha particles at a thin piece of gold foil. It resulted that some particles bounced backwards and some went through the foil. He proposed the particles collided with the dense, positively charged nucleus. -
Rutherford Model
Rutherford's model of the atom was that the centre of an atom consisted of the nucelus, and the region surrounding it was the electron cloud which has negatively charged particles in it. -
Ernest Rutherford
Ernest Rutherford discovered the nucleus of an atom by using the Gold Foil Experiement. -
Bohr Planetary Model
This model consisted of a nucleus that was composed of protons and neutrons at the centre of an atom with energy levels and electrons on it surrounding the centre. -
Henry Moseley
Moseley's discovery was accuratley positioning the known elements in the Periodic Table by using close and careful determination of their atomic numbers. -
Quantum Mechanical Model
This is the most recent model of the atom, which finds the probable position and location of an electron in an atom. -
Niels Bohr
Bohr solved the problem of why negatively charged electrons do not collide with positively charged electrons. He then stated electrons could only be in particular energy levels. Thus, to move between energy levels, energy had to be removed or had to be added from electrons. -
Electron Cloud
Then electron cloud is the area that surrounds the nucleus with negatively charged particles and energy levels. -
James Chadwick
James Chadwick experimented and proved the existence of neutrons.
