Since the day of its existence, humanity tries to solve the things that it has seen or even seen, but that it feels exist. While starting to make sense of what we see and the big things we see, namely space, some scientists and philosophers focused on the small things that we cannot see. As we explained in detail in our article here, these little things were atoms, and the first thoughts about atoms began in the 5th century BC.
Over thousands of years, many different scientists and philosophers developed their own models of the atom. Undoubtedly, although it has deficiencies, the most interesting of these is the Rutherford atomic model. Because this model is very similar to the Solar system, which includes our Earth. Let’s take a closer look at the Rutherford atomic model and see its features and shortcomings.
What is the Rutherford model of the atom?
The Rutherford atomic model is a physical model of the atom that was proposed by Ernest Rutherford, a British experimental physicist from New Zealand in 1911. Rutherford, winner of the 1908 Nobel Prize in Chemistry, revealed this physical model of the atom as a result of his examinations on the results of his experiments.
In the same period as Ernest Rutherford, many scientists worked on the atom and presented different models of atoms. The Rutherford atomic model, like similar models, has some shortcomings, but it must be admitted that the Rutherford atomic model laid the foundations of the Bohr atomic model and the Modern Atomic Theory.
How did the Rutherford model of the atom come about?
Ernest Rutherford, who has been working on the atom for years, decided to do another experiment one day. In this experiment, Rutherford would send particles to a layer and observe their movements. The layer to be used in this experiment would be gold and the particles would be positively charged.
When the day of the experiment came, Rutherford prepared a gold plate with a film on the back. He sent +2 positively charged alpha particles, shown as He+2, towards this layer. As the rays hit the plate, Ernest Rutherford studied the path they took and the effects of the impact. The data he obtained as a result of the investigations was interesting and the Rutherford atomic model emerged.
Rutherford atomic model features:
Ernest Rutherford, as a result of his experiment, was able to calculate the diameter of the atom with a margin that would be considered very small compared to that period. It was just one deviating from the 22,000 positively charged alpha particles sent into the gold layer. Deviation is considered normal because we are talking about the first years of the 20th century.
Ernest Rutherford made the claim that the atom is just like the Solar System as a result of his observations. Accordingly, the nucleus of the atom was positively charged with protons and negative electrons revolved around this nucleus just like planets orbiting the Sun. Rutherford reached some findings accordingly;
- Since most of the rays sent to the gold layer pass directly, there are large gaps in the atom.
- Since a small part of the rays are refracted and reflected, the positive charges in the atom are concentrated in the nucleus.
- Since the larger of the charge is in the nucleus, the atomic mass is also gathered in the nucleus.
- There are as many negative particles as there are positive particles in each atom.
- Positive particles are gathered in the nucleus, while electrons revolve around the nucleus.
- Since electrons are not collected at a single point, they occupy a large part of the atomic volume.
Deficiencies of the Rutherford atomic model:
Rutherford’s model of the atom presented a very successful physical model for its time. It even inspired many models, but unfortunately it did not include the neutron, which is one of the important building blocks of the atom. Likewise, he could not properly explain the motions of electrons. Simply put, the Solar System is also valid in an atom.
The Bohr model of the atom, inspired by the Rutherford atomic model:
The Bohr atomic model was developed in 1911 in the same year as the Rutherford atomic model; It was put forward by the Danish physicist Niels Henrik David Bohr, who would win the Nobel Prize in Physics in 1922. Unlike the Rutherford model of the atom and the theories put forward before it, Bohr studied and explained the movement of electrons in the atom. According to the Bohr atomic model;
- The steady state of electrons moving at a certain distance from the nucleus has a constant energy.
- The stable motion of electrons draws a circular orbit.
- Electron in a stable state does not emit radiation.
- An electron falling from a high energy level to a low energy level emits a quanta of light equal to the varying level difference.
The shortcomings of the Bohr atomic model are as follows;
- He approached the atom only from the framework of classical physics.
- Can only explain single-electron atoms.
- He ignored the wave-particle duality.
- According to the Heisenberg uncertainty principle, the definition of orbital that electrons claim to form is incorrect.
- It does not mention the neutron.
- It is insufficient to explain the bond between atoms and molecules.
Although it is easy to criticize when you look at it today, we answered the questions such as what is the Rutherford atomic model, which was considered quite successful for its period, with which features it stands out and what are its shortcomings. Let us respectfully commemorate all scientists who have shaped today’s scientific world with their work, albeit incomplete.
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