Electrons are subatomic particles that are part of an atom. They have a negative electrical charge and are considered elementary particles, meaning they are not composed of smaller particles.
In an atom, electrons orbit around the atomic nucleus, which consists of protons and neutrons. Protons have a positive charge, neutrons have no electrical charge, and electrons have a negative charge. The number of protons in an atom determines its atomic number and defines the element to which it belongs.
While electrons are indeed small compared to the overall size of an atom, they play a crucial role in determining the chemical and physical properties of elements. The electron cloud, or electron shell, represents the region where electrons are most likely to be found. It surrounds the nucleus and occupies most of the atomic volume.
The behavior of electrons is described by quantum mechanics, a branch of physics that deals with particles at the subatomic level. Quantum mechanics introduces the concept of energy levels and electron orbitals. Electrons occupy specific energy levels and sublevels within an atom, and they can transition between these levels by absorbing or emitting energy in discrete amounts, known as quanta.
The arrangement of electrons in an atom is governed by the principles of the Pauli exclusion principle and the Aufbau principle, among others. These principles define rules for how electrons fill the available energy levels and sublevels.
To summarize, while electrons are much smaller than the overall size of an atom, their behavior and arrangement within the atom are what give elements their unique properties.