29 Questions
What was Thomson's proposed model of an atom?
Thomson proposed that an atom consists of a positively charged sphere with electrons embedded in it, similar to a Christmas pudding with electrons like currants.
How did Thomson describe the distribution of positive charge and electrons in his proposed model of an atom?
Thomson described the positive charge as spread all over the atom like the red edible part of a watermelon, while the electrons are studded in the positively charged sphere, similar to seeds in a watermelon.
What did Thomson propose about the charges in his model of the atom?
Thomson proposed that the negative and positive charges are equal in magnitude, making the atom as a whole electrically neutral.
Why were the results of experiments by other scientists not explained by Thomson's model of the atom?
The results of experiments by other scientists could not be explained by Thomson's model because it failed to account for certain experimental observations.
What was the focus of Ernest Rutherford's experiment regarding the arrangement of electrons within an atom?
Ernest Rutherford designed an experiment to investigate how the electrons are arranged within an atom.
Why did Rutherford select a gold foil for his experiment?
Rutherford chose a gold foil because he wanted as thin a layer as possible to conduct his experiment.
What were the unexpected results of the α-particle scattering experiment?
Most of the fast moving α-particles passed straight through the gold foil, some were deflected by small angles, and a small fraction rebounded.
What did Rutherford conclude from the α-particle scattering experiment?
Rutherford concluded that most of the space inside the atom is empty, the positive charge occupies very little space, and the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.
What were the features of Rutherford's nuclear model of an atom?
The features were: a positively charged nucleus at the atom's center, nearly all the mass residing in the nucleus, and electrons revolving around the nucleus in circular paths.
What were the mass and energy of the fast-moving α-particles?
The mass of the fast-moving α-particles was 4 u, and they had a considerable amount of energy.
What did Rutherford calculate the radius of the nucleus to be, compared to the radius of the atom?
Rutherford calculated that the radius of the nucleus is about 105 times less than the radius of the atom.
What did Rutherford's experiment reveal about the space inside the atom?
Rutherford's experiment revealed that most of the space inside the atom is empty, allowing for the passage of α-particles without deflection.
What did Rutherford conclude about the positive charge inside the atom?
Rutherford concluded that the positive charge of the atom occupies very little space.
What analogy did Thomson use to describe the distribution of positive charge and electrons in his proposed model of an atom?
Christmas pudding or watermelon
Why was Rutherford interested in knowing how the electrons are arranged within an atom?
To understand the internal structure of the atom
What type of particles did Rutherford use in his experiment to probe the structure of the atom?
Alpha (α)-particles
What material did Rutherford select for his experiment, and why?
Gold foil, because he wanted as thin a layer as possible
What did Rutherford propose about the positive charge inside the atom based on the results of his experiment?
The positive charge is concentrated in a small, dense region called the nucleus
What did Rutherford conclude about the space inside the atom based on the unexpected results of his experiment?
The atom is mostly empty space with a small, dense nucleus
What was the mass of the fast-moving α-particles?
4 u
How did Rutherford describe the space inside the atom?
Most of the space inside the atom is empty.
What was the unexpected fraction of α-particles that appeared to rebound?
One out of every 12000 particles
What did Rutherford conclude about the positive charge inside the atom?
All the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.
What did Rutherford calculate the radius of the nucleus to be, compared to the radius of the atom?
About 105 times less than the radius of the atom
What were the features of Rutherford's nuclear model of an atom?
- Positively charged nucleus at the center of an atom. 2. Nearly all the mass of an atom resides in the nucleus. 3. Electrons revolve around the nucleus in circular paths.
What did Rutherford conclude about the distribution of positive charge and mass in the gold atom?
All the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.
Why did Rutherford compare the unexpected results to firing a 15-inch shell at a piece of tissue paper?
To emphasize the unexpectedness of the results
What did Rutherford's experiment reveal about the distribution of positive charge and mass in the gold atom?
All the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.
What did J.J. Thomson win the Nobel prize in Physics for in 1906?
His work on the discovery of electrons
Test your knowledge of Thomson's model of an atom with this quiz. Explore the concept of electrons within a sphere of positive charge, similar to currants in a Christmas pudding or seeds in a watermelon, proposed by J.J. Thomson.
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