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Outline milestones in the development of modern atomic theory
Outline milestones in the development of modern atomic theory
What are the major discoveries in the development of the modern atomic theory?
What are the major discoveries in the development of the modern atomic theory?
Summarize and interpret the results of the experiments of Thomson, Millikan, and Rutherford
Summarize and interpret the results of the experiments of Thomson, Millikan, and Rutherford
1904 - JJ Thompson & the discovery of the electron
1904 - JJ Thompson & the discovery of the electron
1906 Nobel Prize in Physics
1906 Nobel Prize in Physics
The Nobel Prize in Physics 1906 was awarded to Joseph John Thomson "in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases."
video: the electron (4)Who was Thompson and what did he “discover”?
J.J. Thomson was a British physicist who discovered the electron in 1897, identifying it as a fundamental particle smaller than the atom
What was the significance of Thomson's discovery?
The discovery of the electron by J.J. Thomson was significant because it revealed that atoms are not indivisible as previously thought, but contain smaller particles.
Describe the behavior of the electron beam as it’s exposed to the magnetic field.
When exposed to a magnetic field, an electron beam is deflected in a curved path, with the direction and curvature depending on the velocity of the electrons and the field strength.
Describe Thomson's “Plum Pudding” or raisin bread model of the atom.
Thomson's "Plum Pudding" model proposed that the atom consists of a positively charged "pudding" or sphere in which negatively charged electrons (like "plums" or raisins) are embedded. The positive and negative charges were thought to be evenly distributed, making the atom electrically neutral
What did Thompson get right?
Thomson correctly identified the existence of the electron as a negatively charged subatomic particle and showed that atoms contain smaller particles, challenging the idea that atoms were indivisible.
What did Thompson get wrong, or couldn't explain? (think diffuse vs. concentrated charge)
Thomson’s "Plum Pudding" model got the basic structure of the atom wrong, as it assumed that positive charge was diffuse and spread out across the entire atom. He couldn’t explain how the concentrated positive charge found in the atomic nucleus worked.
1909 - Robert Millikan & the elementary charge , (e)
1909 - Robert Millikan & the elementary charge , (e)
1923 Nobel Prize in Physics
1923 Nobel Prize in Physics
The Nobel Prize in Physics 1923 was awarded to Robert Andrews Millikan "for his work on the elementary charge of electricity and on the photoelectric effect."
Who was Millikan and what did he “discover”?
Robert Millikan was an American physicist best known for his oil-drop experiment, which he conducted in 1909. Through this experiment, he measured the charge of the electron with great precision, confirming that electric charge is quantized. (elementary charge)
What is the elementary charge and what was its significance?
The elementary charge is approximately 1.602×10^−19 coulombs and is significant because it represents the smallest unit of electric charge, confirming that electric charge is quantized
How did he figure the value of the elementary charge?
Robert Millikan determined the value of the elementary charge through his oil-drop experiment, where he balanced the gravitational force on tiny oil droplets with an electric field to measure their charge.
1911 - Ernest Rutherford & the discovery of the atomic nucleus
1911 - Ernest Rutherford & the discovery of the atomic nucleus
1908 Nobel Prize in Chemistry
1908 Nobel Prize in Chemistry
The Nobel Prize in Chemistry 1908 was awarded to Ernest Rutherford "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances."
the atom 1 - Rutherford (10).wmvWho was Rutherford and what did he “discover”?
Ernest Rutherford was a physicist who discovered the atomic nucleus and formulated the nuclear model of the atom through his gold foil experiment.
What was the significance of Rutherford's discovery?
Rutherford's discovery of the nucleus was significant because it transformed the understanding of atomic structure, demonstrating that most of an atom's mass and positive charge is concentrated in a small nucleus, which led to the development of the modern atomic model.
Describe Rutherford's “nuclear” model of the atom.
Rutherford's nuclear model of the atom describes an atom as consisting of a small, dense nucleus with electrons orbiting around it, which replaced the earlier "Plum Pudding" model and laid the groundwork for modern atomic theory
What did Rutherford get right?
Rutherford correctly identified that atoms have a small, dense nucleus at their center, which contains most of the atom's mass and positive charge, fundamentally altering the understanding of atomic structure.
What Rutherford got wrong or couldn't explain? (think electrons)
Rutherford incorrectly assumed that electrons could orbit the nucleus like planets without losing energy, failing to explain why they don't spiral into the nucleus due to electromagnetic radiation, a limitation later addressed by Niels Bohr's quantized model of the atom.
1913 - Niles Bohr
1913 - Niles Bohr
1922 Nobel Prize in Physics
1922 Nobel Prize in Physics
The Nobel Prize in Physics 1922 was awarded to Niels Henrik David Bohr "for his services in the investigation of the structure of atoms and of the radiation emanating from them"
the atom 2 - Bohr (6).wmvWho was Niles Bohr, what did he “discover”?
Niels Bohr was a Danish physicist who developed the Bohr model of the atom, which proposed that electrons orbit the nucleus in fixed, quantized energy levels.
What was the significance of Bohr’s discovery?
Bohr’s discovery was significant because it provided a theoretical framework for understanding atomic structure and the behavior of electrons, introducing the concept of quantized energy levels, which explained the discrete spectral lines observed in elements.
Describe Bohr’s “Planetary” model of the atom in your explanation.
Bohr's "Planetary" model of the atom depicts electrons orbiting a dense nucleus in fixed circular paths or energy levels, akin to planets orbiting the sun, and introduced the concept of quantized energy levels to explain atomic spectra
What did Bohr get right?
Bohr correctly identified that electrons occupy specific quantized energy levels around the nucleus
What did Bohr get wrong, or couldn't explain?
Bohr's model incorrectly assumed that electrons travel in fixed orbits around the nucleus and could not explain the behavior of electrons in more complex atoms, nor did it account for the wave-particle duality of electrons, which was later addressed by advancements in quantum mechanics.
1932 - James Chadwick & the discovery of the neutron
1932 - James Chadwick & the discovery of the neutron
1935 Nobel Prize in Physics
1935 Nobel Prize in Physics
The Nobel Prize in Physics 1935 was awarded to James Chadwick "for the discovery of the neutron."
video: the neutron (3)Who was Chadwick and what did he “discover”?
James Chadwick was a British physicist who is best known for discovering the neutron in 1932.
What was the significance of Chadwick’s discovery?
Chadwick's discovery of the neutron was significant because it provided a more complete understanding of atomic structure, revealing that atomic nuclei contain not only positively charged particles but also neutrally charged ones, which contribute to atomic mass and stability.
Describe the three subatomic particles that compose atoms
Describe the three subatomic particles that compose atoms
A timeline of atomic models
A timeline of atomic models
Define isotopes and give examples for several elements
Define isotopes and give examples for several elements
1921 - Frederick Soddy & the discovery of isotopes
1921 - Frederick Soddy & the discovery of isotopes
The 1921 Nobel Prize in Chemistry
The 1921 Nobel Prize in Chemistry
The Nobel Prize in Chemistry 1921 was awarded to Frederick Soddy "for his contributions to our knowledge of the chemistry of radioactive substances, and his investigations into the origin and nature of isotopes."
The Radioactivity Timeline
The Radioactivity Timeline
Radioactivity
A property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously.
Wilhelm Conrad Röntgen
Wilhelm Conrad Röntgen
The Nobel Prize in Physics 1901 was awarded to Wilhelm Conrad Röntgen "in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him."
Henri Becquerel (w/ Pierre Curie & Marie Curie) for the discovery of spontaneous radioactivity
Henri Becquerel (w/ Pierre Curie & Marie Curie) for the discovery of spontaneous radioactivity
The Nobel Prize in Physics 1903 was divided, one half awarded to Antoine Henri Becquerel "in recognition of the extraordinary services he has rendered by his discovery of spontaneous radioactivity", the other half jointly to Pierre Curie and Marie Curie, née Sklodowska "in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel."
Marie Curie, née Sklodowska for the discovery of Radium & Polonium
Marie Curie, née Sklodowska for the discovery of Radium & Polonium
The Nobel Prize in Chemistry 1911 was awarded to Marie Curie, née Sklodowska "in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element."
Frederick Soddy
Frederick Soddy
The Nobel Prize in Chemistry 1921 was awarded to Frederick Soddy "for his contributions to our knowledge of the chemistry of radioactive substances, and his investigations into the origin and nature of isotopes."
Niels Henrik David Bohr
Niels Henrik David Bohr
The Nobel Prize in Physics 1922 was awarded to Niels Henrik David Bohr "for his services in the investigation of the structure of atoms and of the radiation emanating from them."
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