Discovery of Electron, Proton, and Neutron

For a long time, it was thought that atoms were the ultimate particles made up of matter and that these atoms could not be divided any further. Experiments were undertaken in the late nineteenth century and early twentieth century demonstrated that the atom is not the ultimate particle. Scientists’ persistent efforts resulted in the discovery of subatomic particles.

Electron

The electron is a low-mass, negatively charged particle. As a result, passing close to other electrons or the positive nucleus of an atom might readily deflect it.

The first fundamental particle found was the electron. The credit for the discovery of the electron and its attributes goes to J.J. Thomson based on his tests carried out in a discharge tube. He claimed that electrons are essential components of all atoms. J.J. Thomson conducted experiments in a discharge tube with a gas at a low pressure of 0.01mm Hg.

With a mass of 0.000549 AMU, electrons are negatively charged particles. Protons and neutrons weigh around 1836 times as much as electrons. The number of electrons equals the number of protons, resulting in an element’s neutral atom. The chemical properties of an element are determined by its electronic arrangements, whereas the nuclear structure determines the atom’s stability and radioactive transition.

Discovery of electron

J.J.Thomson conducted research in a discharge tube with a gas at a low pressure of 0.01mm Hg. A discharge tube is a long glass tube with two metal plates that are linked to the battery’s oppositely charged poles. These metal plates are referred to as cathode and anode, respectively. Ionization of gas occurs when a high voltage is applied, resulting in the ejection of negatively charged particles known as electrons. Cathode rays are the source of these particles.

Goldstein anticipated the presence of positively charged particles in an atom based on the atom’s electrical neutrality. Goldstein’s discovery of protons was based on an atom’s electrical neutrality. The cathode ray experiment was used by Goldstein in his discovery of protons.

The anode was found to emit the positively charged ions that resulted from the expulsion of electrons. Anode rays or canal rays are the terms for these types of rays. A stream of positively charged particles is known as anode rays or canal rays. The anode rays produced by hydrogen gas in a discharge tube were discovered to be nothing but protons.

The discovery of electrons and protons as subatomic particles within the atom led to the development of atomic models that portray the arrangement of the fundamental particles within an atom.

Proton

Protons are the subatomic particles that has a positive charge, with a a charge of +1.602 * 10-19 Coulombs, with a mass of 1.672*10-27 kg. Except for the hydrogen nucleus, all atomic nuclei are made up of protons and neutrons, which are electrically neutral particles (which consists of a single proton). Each chemical element’s nucleus has the same number of protons. The atomic number of an element is determined by this number, which also determines the element’s location in the periodic table. The atom is electrically neutral when the number of protons in the nucleus equals the number of electrons orbiting the nucleus.

Discovery of proton

When a beam of alpha particles was fired into the air, Ernest Rutherford’s scintillation detectors identified hydrogen nuclei. Rutherford discovered that these hydrogen nuclei were created from nitrogen atoms in the environment after further investigation.

He next used alpha particle beams to bombard pure nitrogen gas, seeing that a greater amount of hydrogen nuclei was created.

He concluded that the hydrogen nuclei came from the nitrogen atom, demonstrating that the hydrogen nucleus was present in all other atoms. This experiment was the first to report a nuclear reaction, which was calculated as 14N + α → 17O + p. [In which is an alpha particle with two protons and two neutrons, and ‘p’ is a proton]

The hydrogen nucleus was eventually dubbed “proton” and identified as one of the atomic nucleus’ building blocks.

Neutron

Neutrons are subatomic particles with no charge. Due to differences in the number of neutrons in their respective nuclei, the masses of two distinct isotopes of an element differ.

In the year 1932, James Chadwick discovered the neutron. They were discovered in an experiment in which an alpha particle bombarded a thin sheet of beryllium. A neutron has a mass of 1.676 * 10-24 grams. The discovery of neutrons dates back to 1930 when German nuclear physicists Herbert Becker and Walther Bothe noticed that when the alpha particles generated by polonium collided with comparatively light materials like lithium, beryllium, and boron, a penetrating kind of radiation was produced. Because electric fields did not affect this penetrating radiation, it was considered to be gamma radiation.

In the year 1920, Ernest Rutherford proposed the presence of neutral particles in the nuclei of atoms. He proposed that the nucleus of atoms contains a neutrally charged particle comprised of a proton and an electron linked together. To describe these neutrally charged particles, he developed the term “neutron.”

Discovery of Neutron

James Chadwick, a scientist, conducted an experiment in which he attacked Beryllium with alpha particles produced by Polonium’s natural radioactive disintegration in 1932. The radiation that resulted had a high penetration through a lead shield, which could not be explained by the particles available at the time. Thus neutrons were produced.

Conclusion

The discovery of electrons and protons was based on the limits of Dalton’s atomic theory in explaining specific phenomena. Neutrons were discovered after more examination. Subatomic particles are the proton, electron, and neutron, which are the building blocks of atoms.