Questions and Answers
What was the overall charge of the atom in Thomson's Plum-Pudding Model?
Which particle did J.J. Thomson consider to be a fundamental particle?
Who discovered radioactivity and coined the term?
What significant contribution did Rutherford make regarding atomic structure?
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What experiment did Rutherford use to demonstrate the shortcomings of Thomson's model?
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What did J.J. Thomson conclude about cathode rays?
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What experimental method did Robert Millikan use to determine the charge of an electron?
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What was the main feature of Thomson's Plum-Pudding Model?
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Which of the following did Thomson conduct in 1897?
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What did the mass-to-charge ratio allow Thomson to determine?
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What analogy was used to describe Thomson's Plum-Pudding Model?
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Which discovery is attributed to J.J. Thomson?
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How were electrons thought to be arranged in the Plum-Pudding Model?
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What primarily contributes to the positive charge of an atom?
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According to Rutherford’s model, how do electrons move around the nucleus?
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What did Rutherford's model imply about the structure of the atom?
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What makes an atom electrically neutral?
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What were neutrons discovered to be in Chadwick’s experiment?
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What was the target material used in Chadwick’s Beryllium-Paraffin experiment?
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What characteristic of neutrons explains why they were not deflected in experiments?
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In Rutherford's Nuclear Model, what happens to the mass of the atom?
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Study Notes
Discovery of Electrons
- J.J. Thomson conducted experiments in 1897 using cathode rays, revealing they could be deflected by magnetic and electric fields, indicating they were composed of charged particles.
- Thomson calculated the mass-to-charge ratio of these particles and found they possessed a net negative charge, coining the term "electron" for these subatomic particles.
Robert Millikan's Experiment
- Between 1906 and 1914, Robert Millikan used electrically charged oil droplets to determine the charge of a single electron.
- Utilized Thomson’s mass-to-charge ratio to calculate the mass of an electron.
J.J. Thomson's Plum-Pudding Model
- Proposed in 1904, suggested that atoms consist of a positively charged matrix that holds most of the atom's mass, akin to "pudding."
- Negatively charged electrons were embedded within this matrix like "plums" in a pudding, distributed uniformly, yielding an overall electrically neutral atom.
- Asserted that electrons were fundamental particles that could not be further divided.
Radiation Discovery
- Henri Becquerel discovered that uranium salts emitted a new form of energy.
- Marie and Pierre Curie introduced the term "radioactivity" to describe this emission of energy rays.
- Ernest Rutherford identified multiple distinct types of radiation emitted by compounds containing uranium and other elements.
Discovery of Protons
- Ernest Rutherford's gold foil experiment demonstrated that Thomson's atomic model was inaccurate.
- Introduced the nuclear model of the atom in 1911, featuring a dense, positively charged nucleus at its center, containing most of the atom’s mass.
Rutherford's Nuclear Model
- Proposed that electrons orbit a central nucleus in fixed energy levels similar to planets around the sun.
- Established the concept that atoms are mostly empty space, with orbiting electrons occupying this volume around the nucleus.
- Emphasized that the atom remains electrically neutral, as the positive charge of the nucleus balances the negative charge of the electrons.
Discovery of Neutrons
- James Chadwick utilized beryllium as a target in experiments, bombarding it with alpha particles and observing a penetrating radiation that was neither electrically charged nor affected by electric/magnetic fields.
- Concluded these neutral particles, with a mass slightly greater than protons, are known as neutrons and possess no electrical charge.
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Description
Test your knowledge on the fundamental aspects of sub-atomic particles, particularly focusing on J.J. Thomson's Cathode Ray Experiment. This quiz covers essential concepts in General Inorganic Chemistry as part of Quarter 1 Week 2b. Dive into the world of electrons and discover their significance in atomic theory.
