Electrons are the negatively charged subatomic particles that revolve around the nucleus of an atom. In this article, we will understand in detail what electrons are, their characteristics, and how they were discovered.
1. What are Electrons? Electrons are the smallest subatomic particles that make up every atom in the universe. They are negatively charged subatomic particles that orbit the nucleus of an atom. They exist as both particles and waves and are involved in chemical reactions and electrical conductivity.
2. Discovery of Electrons In 1897, British physicist J.J. Thomson discovered electrons in cathode ray tubes. His discovery was the first step in understanding the nature of electricity and established the existence of the electron and revolutionized our understanding of atomic structure. He conducted experiments with cathode rays, which demonstrated that they were composed of negatively charged particles (electrons) that were smaller than atoms and had a constant mass-to-charge ratio.
Also Refer: What are Protons? How to find Protons, Neutrons, and Electrons?
2.1 Experiment Cathode ray tubes are glass tubes that have been vacuum-sealed and have had most of the air removed. When a high voltage was applied across two electrodes at one end of the tube, it caused a beam of particles to flow from the negatively charged electrode- cathode to the positively charged electrode- anode. Since the particle beam generated, or "cathode ray," begins at the cathode, the tubes are known as cathode ray tubes.
Thomson examined the cathode ray's properties by wrapping it in two oppositely charged electric plates. He used a high voltage to connect two electrodes at either end of the tube. He observed a stream of particles (rays) emitted from the negatively charged electrode (cathode) to the positively charged electrode (anode). This ray is referred to as a cathode ray, and the entire structure is referred to as a cathode ray tube. This indicated that the cathode rays were composed of negatively charged particles which were named as electrons. Two magnets were also placed on either side of the tube by Thomson and observed that the magnetic field diverted the cathode ray. As a result of these studies, Thomson was able to determine the mass-to-charge ratio of cathode ray particles. The cathode ray experiment conducted by J.J. Thomson in 1897 had several conclusions:
Cathode rays were negatively charged particles.
Electrons were smaller than atoms.
Electrons had a constant mass-to-charge ratio.
Electrons were present in all elements, not just in metals.
3. Characteristics of Electrons Electrons have several important characteristics:
Charge: Electrons are negatively charged particles with a charge of -1.6 x 10-19 Coulombs.
Mass: Electrons have a very small mass of 1/1837 that of a hydrogen atom or approximately 9.11 x 10-31 kilograms.
Size: The electron has an extremely small radius, less than 1x 10-15 m.
Spin: Electrons have a property known as spin, which is a measure of their intrinsic angular momentum.
Orbital motion: Electrons occupy energy levels, or orbitals, around the nucleus of an atom.
Conductivity: Electrons are responsible for the electrical conductivity of metals and play a key role in chemical reactions.
Wave-particle duality: Electrons exhibit both wave-like and particle-like behavior, as described by quantum mechanics.
Interaction with electromagnetic fields: Electrons respond to electromagnetic fields, such as those produced by electric or magnetic fields, and can be manipulated through these fields.
Charge-to-mass ratio: The charge-to-mass ratio of an electron is a fundamental constant and is equal to approximately -1.76 x 1011 coulombs per kilogram (C/kg).
Also Refer: What holds Atoms together in a Molecule?
Key Takeaways
An electron is a negatively charged subatomic particle.
Electrons revolve around the nucleus in shells.
Electrons were discovered by J.J Thomson.
An electron determines an atom's electron configuration, which influences its chemical behavior and reactivity.