Electricity & Megnetism

Basic constituents of an atom

Protons, neutrons and electrons are constituent elements of an atom. In the nucleus of atoms are protons and neutrons. Around the nucleus are electrons.

When dealing with the concepts of electrification, we can know by which process bodies acquire electric charges, or rather, become electrified. This theory is based on the fact that all bodies are made up of atoms. Therefore, each atom has a nucleus, having a certain positive electric charge. This positive charge is due to the presence, in the nucleus, of particles called protons . Also in the nucleus, in addition to protons, there are neutrons , which are particles that have no electrical charge.

Around the nucleus are particles with negative electrical charges called electrons.Normally, the atom is neutral because it has the same amount of negative and positive charges. We also know that the atom is the smallest particle of matter that maintains its properties.

Although there was the concept that the atom would be an indivisible particle, this idea no longer applies, as the atom is divisible and composed of subatomic particles. 

As previously mentioned, among the great variety of component particles of the atom, electrons , neutrons and protons stand out .


As we said, electrons are in orbit around the atomic nucleus. The region where the electrons are located is called the electrosphere. The electron was the first particle to be proven.

It was observed in an experiment involving cathode rays. When in the presence of a magnetic field, the cathode rays changed their trajectory. Today we know exactly that the mass of the electron is 9.11 x 10 -31 kg and that its conventional charge is – 1.6 x 10 -19 C.


The assumption of a particle that did not have an electrical charge (neutral particle ) was proposed by Rutherford in the year 1920. He stated that the particle would have no electrical charge, but its mass resembled the mass of the proton. The discovery of this particle took place through experiments carried out by James Chadwick around 1932.


It was only after several experiments carried out in 1919 that concrete proof of the existence of the proton was obtained. Before this proof, there was the idea of ​​a nucleus with small dimensions and that there would be an electric charge in it.

After several experiments, it was proved that protons are actually found in the nucleus. In the midst of these studies, it was found that these particles have a mass equal to 1.67 x 10 -27 kg. It was then agreed that the charge of the proton is positive.

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