Electrons (The Sub-Atomic Particle)

What are Electrons?

Electrons are the negatively electrically charged particles that whiz around inside an atom.

They were discovered by the English physicist J.J.Thomson in 1897 during some experiments with cathode ray tubes.

An atom is the smallest unit of matter. Maharishi Kanada was the first scientist who came up with the concept of divisibility of matter and named the smallest unit as paramanu.


Electrons – The Sub-atomic Particles

Charge of Electrons

An electron is a negatively charged particle. The negative charge is equal to 1.602 × 10-19 coulomb in magnitude. The mass of an electron is 1/1837 of a proton.

Mass of Electrons

The mass of an electron is 9.10938356 × 10-31 kilograms. The mass of the electron is negligible compared to the mass of the proton.

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Electrons and Compounds

Later, scientists discovered the fundamental sub-atomic particles protons, electrons, and neutrons. An atom has a bulk mass at its centre called a nucleus. The nucleus contains the protons and the neutrons. Considering the solar system, it has been observed that the sun is at its centre, and the planets revolve around it. Similarly, in an atom, the nucleus is at the centre, and the electrons revolve around the nucleus.


Electron structure

The above image clearly shows the structure of an atom and its similarity with the structure of the solar system. The planets in the case of solar system or electrons in the event if an atom revolves around the sun and the nucleus respectively.

The credit for the discovery of electron goes to J.J. Thompson.  He performed an experiment on the cathode rays; he showed that the cathode rays are charged particles. The velocity of cathode rays was much less as compared to the speed of light. He devised methods to measure the charge to mass ratio of cathode rays. Thompson, therefore, concluded that the cathode rays are 1/1000th mass of hydrogen ion (which is a proton). These negatively charged cathode ray particles are now known as electrons.

Electrons are negatively charged particles with negligible mass. The mass of an atom is the sum of the number of protons and neutrons. Protons are positively charged particles whereas neutrons do not carry any charge. The number of protons and electrons is equal hence an atom is electrically neutral in nature. Protons and neutrons together are known as nucleons.

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