Electrons

Electrons are subatomic particles that play a fundamental role in the structure and behavior of matter. Some key characteristics include:

• Charge: Electrons have a negative charge which is equal in magnitude but opposite in sign to the charge of a proton.
• Mass: Electrons have a mass of approximately kilograms, which is about 1/1836 the mass of a proton.
• Location: Electrons are usually said to be “found in the electron cloud,” a region of space around the nucleus of an atom. The electron cloud is divided into shells, each of which can hold a certain number of electrons.
  • It should be noted that this interpretation is simply a way of understanding the quantum mechanical nature of electrons. As quantum particles, electrons can never have a definite position until they are measured. Even then, the electrons position and momentum cannot both be known simultaneously. This is due to the heisenburg uncertainty principle which states that: .
• Energy: Electrons have energy levels associated with them. The energy level of an electron determines its distance from the nucleus and its potential energy. Electrons can move between energy levels by absorbing or emitting energy, which can be in the form of light, heat, or other forms of electromagnetic radiation.
• Behavior: Electrons exhibit wave-particle duality, meaning they can behave as both waves and particles. They follow the laws of quantum mechanics which govern the behavior of particles on a very small scale. The figure below depicts the electron distribution for the classic double slit experiment. Note that the quantum mechanical behavior of electrons leads to the collapsing of the wave function upon observaation. In other words, if no detector is present, the electrons behave as waves, generating an interference pattern with intensity as depicted on the left. However, if some detector is present, the slit through which the electron passes is known and the distribution is as shown on the right. This betrays intuition as we expect that electrons would behave the same way regardless of whether or not a detector is present. Regardless, this wave-particle duality is essential to the true definition of electrons (as with all particles and matter).

• Spin: Electrons have an intrinsic angular momentum, or spin, that is always either up or down. The spin of an electron is important in determining its behavior in a magnetic field. This is analogous to the spin of a spinning top. However, electron spin is not a physical spin. Otherwise, the angular speed of the electron could potentially surpass the speed of light which is not possible by Einstein’s theory of relativity.
• Electromagnetism: Electrons are involved in the electromagnetic force which is responsible for the interaction between charged particles. This force is the basis for many of the phenomena we observe in the physical world.
• Bonding: Electrons are involved in chemical bonding, which is the process by which atoms combine to form molecules. The arrangement of electrons in an atom determines its chemical properties, and the sharing or transfer of electrons between atoms is what allows chemical reactions to occur.
• Applications: Electrons are essential for many modern technologies, including computers, televisions, and other electronic devices. They are also used in medical imaging, such as in X-rays and MRI scans.

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