The electron possesses several observable properties that led to its classification as a particle. Here are four key properties:
Charge: The electron has a fundamental electric charge, which is negative. Its charge was determined through various experiments, such as the Millikan oil drop experiment, where the charge of individual electrons was measured. The presence of a discrete and quantized charge indicates its particle-like behavior.
Mass: The electron has a well-defined rest mass, which is approximately 9.11 x 10^-31 kilograms. The determination of its mass was carried out through experiments like the famous Thomson's cathode ray tube experiment, which involved measuring the deflection of electron beams in electric and magnetic fields. The existence of a definite mass contributes to its particle nature.
Momentum: The electron exhibits momentum, a property associated with particles. Experiments like electron diffraction, where electrons behave as waves and undergo interference, demonstrate that they possess momentum. The measurement of an electron's momentum allows for the determination of its velocity and confirms its particle-like behavior.
Spin: The electron possesses an intrinsic property known as spin, which is a form of angular momentum. Although spin is a quantum property not directly related to classical spinning motion, it is an observable property that distinguishes particles from waves. The measurement of electron spin can be performed through experiments such as the Stern-Gerlach experiment, which revealed the quantized nature of electron spin.
These properties, among others, establish the electron as a particle with discrete characteristics, distinct from the behavior of waves. The combination of charge, mass, momentum, and spin confirms the particle-like nature of the electron and forms the basis of our understanding of its behavior in the framework of quantum mechanics.