17 Questions
What did James Chadwick provide evidence for, 20 years after the 'nucleus' was accepted as a scientific idea?
Existence of neutrons
In radioactive decay, what is defined as the rate at which a source of unstable nuclei decays?
Activity
Which type of radiation is highly ionizing and weakly penetrating?
Alpha α (helium nucleus)
What is the unit used to measure the count-rate of decays recorded by a detector per second?
Becquerel
What is the name for the random process by which atomic nuclei undergo radioactive decay to become more stable?
Radioactive decay
Which scientist's experiment led to the discovery that electrons exist in fixed 'orbitals' within an atom?
Niels Bohr
According to the Rutherford model, what did the results of the gold foil experiment suggest about the structure of an atom?
The atom is mostly empty space with a dense, positively charged nucleus at the center.
Which model of the atom proposed that electrons orbit the nucleus in specific energy levels or shells?
Bohr model
What is the primary difference between the Rutherford model and the Bohr model of the atom?
The Rutherford model assumes a solid, indivisible structure, while the Bohr model proposes a nucleus surrounded by orbiting electrons.
What is the primary limitation of the Bohr model of the atom?
It cannot explain the emission spectra of elements other than hydrogen.
Which subatomic particle was discovered during the gold foil experiment conducted by Rutherford?
Proton
What is the primary difference between the concepts of contamination and irradiation in the context of radioactivity?
Contamination involves the presence of radioactive atoms on materials, while irradiation is exposure to radiation from a source.
What was the main conclusion of the Rutherford Gold Foil Experiment?
Most of the atom is empty space, with a small, dense, positively charged nucleus.
According to the Bohr model of the atom, why did the electrons not collapse into the nucleus?
The electrons existed in specific, quantized energy levels or orbitals around the nucleus.
What was the key difference between the Rutherford model and the Bohr model of the atom?
The Rutherford model had electrons orbiting the nucleus, while the Bohr model had electrons in specific energy levels.
What was the primary reason the Plum Pudding model of the atom was abandoned?
It could not explain the results of the Rutherford Gold Foil Experiment.
What was the significance of the few alpha particles that were deflected by more than 90 degrees in the Rutherford Gold Foil Experiment?
It indicated that the nucleus contains most of the mass of the atom.
Learn about the historical evolution of the atomic model from Dalton's concept of indivisible spheres to Thomson's Plum Pudding Model and Rutherford's Gold Foil Experiment. Understand the key discoveries and changes that led to our modern understanding of the atom.
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