In a previous post, it was discussed how electrons behave like tiny magnets because they spin around their angular axis of rotation and also revolve around the atomic nucleus. Here we will try to understand words like spin, rotation, angular axis and some more associated terms.
Understanding Momentum
Momentum is a word that is part of our everyday vocabulary. How many times have you felt or said that you were unable to work because your momentum was not building up? So what is this momentum? Momentum is the quantity of motion of a moving body. Simply speaking, momentum measures the “motion” of an object that is moving. It is calculated based on the weight of the object and its velocity. So, if an object is not moving, i.e., at rest, its momentum would be 0 (zero).
Momentum of Electrons
Electrons are continuously moving inside the atom. So, they too have momentum. Electrons have two types of motions:
- Orbital Motion: Electrons revolve around the nucleus of the atom. This is called electron orbital motion.
- Spin Motion: Electrons rotate on their own axis. This is called electron spin.
Since there are two types of motion associated with electrons, they have two types of momentum as well, as shown in the Figure below.
Figure 1: Angular Momentum of electron
Angular Momentum of Electrons
Rotation and revolution of any body is always measured with respect to its axis. In the case of electrons, the axes of both orbital and spin motion are not linear but angular, so associated momentum is called angular momentum. The momentum due to orbital motion is called orbital angular momentum. The momentum due to spin is called spin angular momentum.
Angular momentum is what makes the electron behave like a tiny magnet. There are other effects of angular momentum but they are quite conceptual and let’s leave them to a later post. At least till the time you gain enough momentum to delve deeper into the physics of electrons!!
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