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Questions and Answers
What did Thomson discover about the cathode rays in his experiment?
What did Thomson discover about the cathode rays in his experiment?
In Rutherford's experiment, what were the three observations he made?
In Rutherford's experiment, what were the three observations he made?
After Rutherford's experiment, what conclusions did he draw?
After Rutherford's experiment, what conclusions did he draw?
Which scientist conducted an experiment with a cathode ray and discovered electrons?
Which scientist conducted an experiment with a cathode ray and discovered electrons?
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What type of view in Rutherford's experiment allowed him to make conclusions about atoms?
What type of view in Rutherford's experiment allowed him to make conclusions about atoms?
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According to Dalton's atomic theory, atoms are:
According to Dalton's atomic theory, atoms are:
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In Thomson's model of the atom, atoms contained:
In Thomson's model of the atom, atoms contained:
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According to the Bohr Planetary Model, electrons:
According to the Bohr Planetary Model, electrons:
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Which scientist proposed the idea that the centre of the atom has a positive charge?
Which scientist proposed the idea that the centre of the atom has a positive charge?
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In the nuclear model proposed by Rutherford, the majority of the atom is made up of:
In the nuclear model proposed by Rutherford, the majority of the atom is made up of:
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Chadwick discovered that the nucleus of an atom contains protons and:
Chadwick discovered that the nucleus of an atom contains protons and:
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Study Notes
Thomson's Discoveries
- Discovered that cathode rays are streams of negatively charged particles, later named electrons.
- Demonstrated that cathode rays could be deflected by electric and magnetic fields, indicating their charge.
Rutherford's Experiment Observations
- Most alpha particles passed through the gold foil without deflection, suggesting a lot of empty space in atoms.
- A small fraction of alpha particles were deflected at large angles, indicating the presence of a dense core.
- A very few alpha particles were reflected back toward the source, revealing that the nucleus is positively charged.
Rutherford's Conclusions
- Proposed that atoms consist of a small, dense positively charged nucleus surrounded by electrons.
- Introduced the idea of the nuclear model of the atom, shifting away from previous models based on uniform density.
Discovery of Electrons
- J.J. Thomson conducted experiments using cathode rays to discover the existence of electrons.
Rutherford's View on Atoms
- Utilized a scattering experiment design, allowing for direct observation of interactions between alpha particles and atomic structure.
Dalton's Atomic Theory
- Atoms are indivisible and indestructible particles, which combine in whole-number ratios to form compounds.
- All atoms of a given element are identical in mass and properties.
Thomson's Atomic Model
- Proposed the "plum pudding" model, where atoms contain electrons embedded in a positively charged "soup."
Bohr Planetary Model
- Electrons orbit the nucleus in defined energy levels, and can jump between levels when absorbing or emitting energy.
Positive Charge in Atoms
- Ernest Rutherford proposed that the center of the atom contains positive charge, known as the nucleus.
Rutherford's Nuclear Model
- The majority of the atom is empty space, with a small, dense nucleus at the center comprising protons and neutrons.
Chadwick's Discovery
- Discovered that the nucleus also contains neutrons, which are neutral particles that contribute to the mass of the atom.
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Description
Test your knowledge on the history of the atom by filling in a chart with information about key scientists and their atomic models. Topics include Democritus, Aristotle, Dalton, and Thomson's contributions to our understanding of the atom.
