In Chemistry, understanding the atomic structure of an Atom is vital. Let’s start with the basics, explain what the Rutherford Atomic Model was and why it was inadequate to give details for the structure of an Atom.
Rutherford’s Atomic Model Limitations are also explained in this article.
What do you mean by Structure of Atoms?
The definition of atomic structure is positively charged nucleus and negatively charged electrons circling within an atom. The atomic structure of all the matter is made up of protons, electrons, and neutrons.
- The nucleus of an atom consists of positively charged protons and neutrons.
- The nucleus of an atom is all surrounded by the electrons which belong to the atom.
- An element’s Atomic Number is defined by the number of protons present in an atom’s nucleus.
- The atoms with an equal number of protons and electrons are Neutral atoms. The atom has the nature of gaining and losing electrons to increase its stability. Hence, this newly charged entity that is formed is termed an ion.
- The atomic structures are different for different elements. That’s because different elements have atoms containing a different number of electrons and protons. Therefore different elements have unique characteristics.
We know that the structure of an atom consists of electrons, protons, and neutrons. This was accurately presented when many scientists came forward with different atomic structure models.
A significant model of the lot was the one proposed by Ernest Rutherford, named the Rutherford Atomic Model. However, it is not considered the accurate representation of an atom anymore. Let us know more about this model.
Atomic Model of Rutherford
A well-known British scientist, Ernest Rutherford, experimented with the structure of the atom and gave his observations, and based on all such observations, proposed the atomic model.
Rutherford’s Alpha Scattering Experiment
Rutherford’s experiment details how the α-particles were bombarded through gold foil and then details the trajectory made by alpha particles after the particles interact with a thin sheet of gold.
The Scientist, in his atomic model experiment, directed a high-energy stream of particles of alpha from a source at gold foil with 100 nm of its thickness. To understand the α-particles deflection, he also placed a screen of fluorescent zinc sulfide surrounding the gold foil.
Observations of Rutherford’s Alpha Scattering Experiment
The following points detail Rutherford Observations on his Atomic Structure model, which future helped to conclude the following points explained below:
- A large part of α- particles were bombarded through a thin sheet of gold, some of the particles did pass through it without any deflection, so it was observed that most of the atom is empty-spaced.
- While some of the particles passed through without being reflected, some of them were deflected by a thin sheet of gold, making very small angles. Hence, it was noted that there is no uniform distribution of the positive charge in the atom.
- The number of α- particles deflected back we’re very few, the particles deflected making nearly 180-degree angle. Hence the positively charged particles have less volume as compared to the total volume of particles.
- In an Atom, the nucleus’s size is very small compared to the total size of an atom.
Atomic Model of Rutherford: Deductions
As per the above observations and evaluations, Rutherford came forward with his theory of Atomic Structure. As per his model:
- The positively charged particles and most of the mass of the atom were concentrated in extremely small volumes. Rutherford called this part of the atom its nucleus.
- The Scientist model proposed that the electrons which are negatively charged surround the nucleus of the atom. He even stated that the electrons revolve around the nucleus at very high speed in circular paths. He named these circular paths orbits.
- The nucleus of the atom charged positively, and the negatively charged electrons revolving around it are held closely together in a bond by a robust electrostatic force of attraction.
Atomic Model of Rutherford: Limitations
- Rutherford developed his theory of the Atomic Model after multiple experimental observations. However, his model still failed to explain various things, which are detailed as below.
- The Atomic model of Rutherford stated that the electrons did revolve around the atom’s nucleus on fixed paths, which were known as orbits.
- According to Maxwell, the accelerated charged particles of an atom emit electromagnetic radiation. Hence, electromagnetic radiation is emitted by the electrons that revolve around the nucleus.
- And due to the electron’s continuous motion, the radiation would carry energy. This energy would result in shrinking orbits, which would ultimately lead to collapsing electrons in the nucleus.
- According to the Rutherford model, an electron would collapse in less than 10 to 8 seconds in the nucleus.
- Rutherford’s model did not state the arrangement of electrons in an atom which is essential to define the structure of the atom. This made Rutherford’s theory an incomplete theory.
Drawbacks of Rutherford Atomic Model
- According to Rutherford’s atomic model, the electrons (planets) move around the nucleus (sun) in well-defined orbits. Since a body that moves in an orbit must undergo acceleration, the electrons, in this case, must be under acceleration. If this is true, then the electron will spiral into the nucleus. However, that does not take place. Hence, Rutherford’s model fails to explain the stability of the atom.
- Contrarily, let’s consider that the electrons do not move and are stationary. Then the electrostatic attraction between the electrons and the dense nucleus will pull the electrons into the atom’s nucleus to form a miniature version of Thomson’s model.
- Rutherford’s model also does not state anything about the distribution of the electrons around the nucleus in an atom and the energies of these electrons.
With all the details given above regarding the Rutherford model, we hope that the article can provide complete knowledge about Rutherford’s model and its related limitations of the Atomic structure model.
Even though the early atomic models given by most popular scientists were inaccurate and failed to explain certain experimental results, they formed the base for future developments in the world of quantum mechanics.