As a fundamental particle, the electron is indivisible and is one of the building blocks of matter. It is classified as a lepton, a category of particles that do not experience the strong nuclear force but do participate in weak nuclear interactions and electromagnetic interactions.
Michael Faraday (1830):
Faraday's experiments with electrolysis showed that electricity passing through an electrolyte causes chemical reactions at the electrodes, indicating the particulate nature of electricity. This laid the groundwork for understanding the behavior of charged particles.
Here is a brief introduction about Cathod ray experiments-
Observation:
The flow of cathode rays can be detected by making a hole in the anode and coating the area behind it with fluorescent or phosphorescent material like zinc sulfide. When cathode rays strike the coating, a bright spot is formed.
Cathode rays move from the cathode to the anode and are invisible but detectable by their effect on fluorescent materials. They travel in straight lines without fields and behave like negatively charged particles in electric or magnetic fields, indicating they are electrons.
Conclusion
Electrons exhibit dual characteristics of both waves and particles. This duality is evident in phenomena such as the double-slit experiment, where electrons can form interference patterns, demonstrating their wave-like behavior.
In quantum mechanics, the behavior of electrons is described by wavefunctions, which provide the probability distribution of an electron’s position and momentum.
Electrons are found in atomic orbitals, which are regions around the nucleus where the probability of finding an electron is highest. These orbitals are arranged in energy levels or shells.
The arrangement of electrons in these orbitals determines an atom's chemical properties and reactivity. This configuration follows principles like the Aufbau principle, Hund's rule, and the Pauli exclusion principle.
Electrons are key to forming chemical bonds. In covalent bonds, electrons are shared between atoms, while in ionic bonds, electrons are transferred from one atom to another.
Electrons interact with other charged particles through the electromagnetic force, which is described by Coulomb's law. This law states that like charges repel each other while opposite charges attract.
Electrons can absorb and emit photons, causing transitions between different energy levels. This interaction is fundamental to processes like fluorescence, phosphorescence, and the emission of light from excited atoms.
Example :
(Session 2025 - 26)