Please enable JavaScript.
Coggle requires JavaScript to display documents.
Atomic Theories, James Chadwick’s Discovery of the Neutron (1932),…
Atomic Theories
Rutherford’s Nuclear Model (1911)
Key Points:
Electrons orbit around the nucleus (but not in defined paths).
Significant Details
Explained that some alpha particles bounced back, indicating a dense center.
Couldn’t explain why electrons don’t spiral into the nucleus.
Lacked defined orbits and didn’t explain atomic spectr
Disproved Thomson’s Plum Pudding Model.
Model
Explanation
https://youtu.be/WEPMwhNsLbU
J.J. Thomson’s Plum Pudding Model (1897)
Key Points
Discovered the electron using a cathode ray tube.
Proposed the Plum Pudding Model of the atom.
Atom is a positively charged sphere with scattered negative electrons.
First to show that atoms have internal structure.
Significant Points
Overturned Dalton’s idea of indivisible atoms.
Model couldn’t explain the existence of a nucleus.
Later disproved by Rutherford’s gold foil experiment.
Showed that atoms contain smaller particles.
Model
Explanation
https://youtu.be/HNGz5cBAjEc
Bohr’s Planetary Model (1913)
Keypoints
Built on Rutherford’s model using quantum theory.
Electrons move in fixed orbits (energy levels).
Electrons absorb/emit energy when jumping between levels.
The model explains the line spectra of hydrogen.
Significant Details
Introduced the idea of quantized energy.
Prevented electrons from collapsing into the nucleus.
Worked only for hydrogen, not multi-electron atoms.
Eventually replaced by the Quantum Mechanical Mode
Model:
Explanation
https://youtu.be/S1LDJUu4nko
Dalton’s Atomic Theory (1803)
Keypoints
Proposed the first modern atomic theory based on experiments.
Atoms are indivisible and make up all matter.
Atoms of the same element are identical.
Compounds are formed by atoms in fixed, whole-number ratios.
Chemical reactions involve the rearrangement of atoms.
Significant Points
Revived ancient atomic ideas with scientific evidence.
Provided a foundation for later atomic models.
Assumed atoms were solid spheres (no subatomic particles).
Couldn’t explain isotopes or internal structure of atoms.
Model
Explanation
https://youtu.be/h-tZHYiaCnc
James Chadwick’s Discovery of the Neutron (1932)
Explnation
https://youtu.be/2bNdMzbIuzw
Key Points
Significant Details
Model
Disproved Thomson’s Plum Pudding Model.
Couldn’t explain why electrons don’t spiral into the nucleus.
Lacked defined orbits and didn’t explain atomic spectra.
Explained that some alpha particles bounced back, indicating a dense center.
Proposed the Nuclear Model after his Gold Foil Experiment.
Atoms are mostly empty space.
A small, dense, positively charged nucleus is at the center.
Electrons orbit around the nucleus (but not in defined paths).
Proposed the Nuclear Model after his Gold Foil Experiment.
A small, dense, positively charged nucleus is at the center.
Atoms are mostly empty space.
