Which of the following statements are TRUE of the plum-pudding model? (select all that apply)? 1. It’s validated by the Rutherford Gold Foil Experiment. II. It describes atoms as having a positively-charged core called the nucleus. III. It predicts a spherical/circular shape for the atom. IV. The model is no longer accepted by today’s standards.
The Correct Answer and Explanation is :
The correct statements are:
- III. It predicts a spherical/circular shape for the atom.
- IV. The model is no longer accepted by today’s standards.
Explanation:
The plum-pudding model of the atom, proposed by J.J. Thomson in 1904, was one of the early attempts to describe the structure of atoms. It was based on the idea that atoms are made up of a uniform, positively charged “pudding” with negatively charged electrons embedded within it like “plums.” Here’s an analysis of the provided statements:
- It’s validated by the Rutherford Gold Foil Experiment – False
- The plum-pudding model was disproven by Ernest Rutherford’s gold foil experiment in 1911. Rutherford’s experiment revealed that most of an atom’s mass is concentrated in a small, dense, positively charged nucleus at the center of the atom, with electrons orbiting around it. This result led to the development of the Rutherford model, which contradicted the plum-pudding model.
- It describes atoms as having a positively-charged core called the nucleus – False
- The plum-pudding model did not have a nucleus. It suggested that the positive charge was spread out uniformly throughout the atom, with the negative electrons scattered within. The concept of a central nucleus was introduced later by Rutherford.
- It predicts a spherical/circular shape for the atom – True
- The plum-pudding model predicted that the atom would be roughly spherical, with the positive charge spread throughout and the electrons distributed in a way that balanced the positive charge. This gave the atom an overall neutral charge.
- The model is no longer accepted by today’s standards – True
- The plum-pudding model was eventually replaced by more accurate atomic models, including Rutherford’s and later Niels Bohr’s model, which described more precise structures for atoms, including the existence of a dense nucleus and orbiting electrons.
In summary, while the plum-pudding model was an important early attempt, it was later proven incorrect and is no longer accepted in modern atomic theory.