Question

Describe Rutherford’s gold foil experiment and how the experimental results led to specific changes in the accepted model of the atom. Be sure to include a description of the atomic model that was accepted by the scientific community before this experiment as well as the atomic model that was accepted after this experiment.

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Answer 1

Rutherford's experiment involved alpha particles and a thin gold foil, revealing unexpected deflections which led to the discovery of the atomic nucleus and the planetary model of the atom, replacing Thomson's plum pudding model.

Step-by-step explanation:

Before Rutherford's experiment, the accepted atomic model was Thomson's "plum pudding" model, which posited that an atom consisted of a diffuse cloud of positive charge with negatively charged electrons embedded within it. During Rutherford's gold foil experiment, alpha particles (positively charged particles) were directed at a thin sheet of gold foil. The expectation was that these particles would pass through with minimal deflection, as Thomson's model suggested the atom was largely empty space without a concentrated center of mass.

Contrary to expectations, while most alpha particles passed through the foil, a small fraction was deflected at large angles, and a very few even bounced back. Rutherford concluded that the positive charge and most of the atom's mass had to be concentrated in a small central core, which he called the nucleus. The nucleus was surrounded by empty space through which the electrons moved. This gave rise to Rutherford's planetary model of the atom, where the electrons orbit the nucleus like planets around the sun.

The experiment was crucial as it disproved the plum pudding model and led to the acceptance of the nuclear model of the atom, where the atom is mostly empty space with a dense nucleus containing protons (and later discovered, neutrons) surrounded by electrons in orbit.Rutherford's model laid the groundwork for modern atomic physics and quantum theory, explaining atomic structure and radiation spectra, although it could not explain the stability of the electrons in orbit.

Answer 2

Before Rutherford's discovery, the accepted atomic model was J. J Thompson's Plum Pudding Model. According to J.J Thompson, the atom is composed of negatively charged particles. They were then called 'corpuscles', but now known to be electrons. Outside of this atom, surrounds a cloud of positively charged electrons to balance out the charge of electrons, which makes the atom neutral. The 'plum' were the electrons, whereas the 'pudding' were the protons.

Through Rutherford's gold foil experiment, he disproved J.J Thompson's theory. Rutherford was very interested in studying the behavior of x-rays, which was then recently discovered by Curie. When he shot a beam of alpha particles (particles with 2 neutrons and 2 protons, or the Helium atom) toward the gold foil, the particles were deflected by a slight angle. He then theorized that these deflections were due to the existence of a dense nucleus inside the atom.

Following Rutherford's discovery of the nucleus, Niels Bohr theorized the planetary model of the atomic structure. According to him, the atom is like a solar system wherein the Sun is the nucleus and the planets are the electrons orbiting around it. The electrons and protons move this way because they are influenced by an electric force due to the difference of their charges.