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Scientists and their discoveries for understanding the atomic theory
Empedocles (500 B.C)
All matter is made up of water, earth, air & fire |
Democritus (300 B.C)
Known as The Laughing Philosopher |
Atoms are indivisible, indestructible, in motion & differs in shapes and sizes |
John Dalton (Early 1800s)
Billiard Ball Model / Solid Sphere Model |
Atoms can't be destroyed, subdivided or created |
Atoms of the same element have identical properties; Atoms from different elements have different properties |
During chemical reactions, atoms can be rearranged, separated or created |
Atoms are combined in simple whole number ratios |
J.J Thompson (Late 1800s)
Plum Pudding Model |
Discovered that electrons are stuck in a positively charged matter |
Conducted the cathode-ray experiment; Beta particles were attracted to the positively charged magnets |
Ernest Rutherford (1911)
Nuclear Model / Rutherford's Model |
Dense, tiny positively charge in the centre of an atom |
Several spaces in an atom |
Most of the mass is in the nucleus |
If J.J Thompson's discovery was accurate, the particles would've had minor deflects, but there were major deflects |
Gold foil was used b/c it is the most malleable metal |
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Niels Bohr (1913)
Planetary Model / Bohr's Model |
Electrons emit photons (quantum of light) jumps up or down to other shells and doesn't spiral into the nucleus while emitting photons |
Max Planck
Proposed that particles can emit a certain amount of electromagnetic radiation |
Electrons need to obtain the amount of energy before emitting it |
Analogy: Similar to a bank machine...you can only receive multiple of $20.00, although other amounts exit (e.g. $32.00) |
Werner Heisenberg's Uncertainty Principle
It's impossible to know both the position (location) & the momentum (speed) of a particle at any given moment |
Erwin Schrodinger (1926)
Quantum Mechanical Model |
Mathematically predicted the regions of space where electrons can be found |
De Broglie
Quantum Mechanical Model |
Electrons behave like waves & particles |
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