Subatomic Particles: Electrons, Protons and Neutrons

A subatomic particle is a particle a size smaller than that of an atom. Protons, electrons, and neutrons are the three subatomic particles that typically make up an atom. Atoms are the fundamental components of matter. As a result, the existence of various types of matter around us is due o the presence of atoms in them.

Experiments in the late 1800s and early 1900s revealed that the atom isn’t the ultimate particle. Subatomic particles were discovered as a result of the scientists’ tireless efforts. Students may develop a firm foundation around vital courses like Physics when complicated issues are reduced and explained. This article will explain how atoms are divisible by the particles that make up their interiors, known as subatomic particles.

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What are Subatomic Particles?

A subatomic particle is smaller than an atom and cannot be seen by our naked eyes. There are three subatomic particles called electrons, protons, and neutrons. Electrons have a negative charge, protons have a positive charge, neutrons have no charge. The particles are held within the atom by four fundamental forces- gravity, electromagnetic force, strong force, and weak force.

Electrons

Electrons are the smallest particle of an atom that has a negative charge on it. It revolves around the nucleus in an atom and is represented by \( {e^ – }\).

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Discovery of Electrons

William Crooks, a British scientist, noted that gases are poor conductors of electricity. However, the gas becomes a conductor, and the travelling current starts to flow through the gas at a low pressure around \(0.001\,{\text{mm}}\,{\text{Hg}}\) and a high voltage of \(10000\, {\text{V}}\).

Later, an English scientist J.J Thomson studied the characteristics of the cathode ray and discovered the electron in \(1897\) through his experiment.

Subatomic Particle Experiment

A glass tube fitted with two metallic electrodes called cathode and anode. A gas tube’s pressure was controlled with the help of a vacuum pump connected with the tube. The electrodes were connected to a source of high voltage. The pressure taken was very low, about (0.001\,{\text{mm}}\,{\text{Hg}}), and high voltage of about (10000\, {\text{V}}).

The cathode rays were produced. Further experiments showed that cathode rays are made of negatively charged particles called electrons.

Properties of Cathode Rays

1. The cathode rays start at the cathode and travel towards the anode.
2. These rays are only visible through phosphorescent materials.
3. They cause a greenish-yellow fluorescence on a soda glass screen placed in the tube.
4. They are inflected by a positive field and deflected by a negative field when placed in an electric field.
5. When placed in an electric field, they are inflected by a positive field and deflected by a negative field.
6. They penetrate through matter.

Characteristics of Electrons

1. The mass of an electron is \(1/1837\), the mass of a hydrogen atom or \(9.108 \times {10^{ – 31}}\,{\text{kg}}\).
2. An electron carries a unit negative charge and has a magnitude of \(1.602 \times {10^{ – 19}}\) coulombs.
3. The electron is extremely small; its radius is less than \(1 \times {10^{ – 15}}\,{\text{m}}\).

Protons

Protons are the particles of an atom that have a positive charge on them. It is present in the nucleus of an atom and is represented by \({{\text{p}}^{\text{ + }}}\).

Discovery of Protons

Goldstein discovered a positively charged particle, but the credit for the discovery of protons is given to Ernest Rutherford. In (1886), Goldstein noticed that in addition to cathode rays, another set of rays travelled in an opposite direction. From anode to the cathode when a perforated cathode was used above the discharge tube.

Anode Rays Experiment

A glass tube fitted with two metallic electrodes called cathode and anode. The tube was filled with a gas, and the pressure of the gas was controlled with the help of a vacuum pump connected with the tube. The electrodes were connected to a source of high voltage. The pressure taken was very low, about \(0.001\,{\text{mm}}\,{\text{Hg}}\), and high voltage of about \(10000\, {\text{V}}\).

Anode rays were produced. Goldstein called these rays canal rays since these rays passed through the holes or canals in the cathode. These rays were found to consist of positively charged particles.

Properties of Anode Rays

1. They travel in a straight line.
2. They start from the cathode and move towards the anode.
3. These rays are deflected by a positive field and attracted by a negative field when placed in an electric field.
4. These rays produce a heating effect when struck against a metallic foil.
5. They constitute minute material particles and hence produce mechanical effects.

Gold Foil Experiment

Rutherford bombarded alpha particles on an ultra-thin gold foil. Most of the alpha particles were undeflected, some particles got deflected at a small angle, and only \(1\) out of \(8000\) particles bounced off the gold foil at extensive angles. Thus, he concluded that the atom is mostly empty space with a tiny, dense, positively charged nucleus.

Characteristics of Protons

1. The proton’s mass is the same as that of a hydrogen atom that is \(1837\) times the mass of an electron which is \(1.672 \times {10^{ – 24}}\,{\text{g}}\).
2. A proton carries a positive unit charge and has a magnitude of \(1.602 \times {10^{ – 19}}\) coulombs.
3. The proton resides in the central part of the atom that is in its nucleus.

Neutrons

Neutrons are the particles of an atom that has no charge on them, and it resides in the central part of the atom that is the nucleus. Its mass is almost equal to that of a proton. It is usually represented by \(\rm{n}\) or \({\text{n}}^{\text{0}}\).

Discovery of Neutrons

In 1932, Chadwick discovered neutrons by bombarding light nuclei atom-beryllium with alpha particles. He found that these new particles have no charge on them and were thus named neutrons.

Characteristics of Neutrons

1. An electric and magnetic field does not deflect these particles.
2. Its mass is equal to \(1.676 \times {10^{ – 24}}\,{\text{g}}\,\left({1\,{\text{amu}}}  \right)\).

Summary

This article teaches that an atom is a divisible particle and can further be divided into electrons, protons, and neutrons. It also includes the discoveries of these particles and their characteristics.

FAQs

Q.1. What are the features of subatomic particles?
Ans: Some of the features of subatomic particles are:
– A subatomic particle is a particle smaller than an atom.
– Our naked eyes cannot see them.
– There are three subatomic particles called electrons, protons and neutrons.
– Electrons have a negative charge, and protons have a positive charge, and neutrons have no charge.
– The subatomic particles are held within the atom by one of the four fundamental forces- gravity, electromagnetic force, strong force, and weak force.

Q.2. What are the three subatomic particles?
Ans: There are three subatomic particles-electrons, protons and neutrons. Electrons are negatively charged particles, protons are positively charged particles, and neutrons are neutrally charged particles.

Q.3. What are the subatomic particles made of?
Ans: Electrons are fundamental particles, and they belong to the first generation of the lepton particle family. Protons and neutrons are composite particles made of quarks.

Q.4. Why are the subatomic particles important?
Ans: There are three subatomic particles-electrons, protons, and neutrons. They are important because they are the building block of matter.

Q.5. What are neutrons?
Ans: Neutrons are the particles of an atom that has no charge on them, and it resides in the central part of the atom that is the nucleus. Its mass is almost equal to that of a proton.

Q.6. What are protons?
Ans: Protons are the particles of an atom that have a positive charge on them. It is present in the nucleus of an atom.

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