In physics, a particle is defined as a fundamental unit of matter or energy that exhibits certain properties and behaves according to the laws of physics. Particles can be classified into two broad categories: elementary particles and composite particles.
Elementary Particles: Elementary particles are the building blocks of matter. They are considered fundamental and indivisible, meaning they cannot be broken down into smaller constituents. According to the Standard Model of particle physics, elementary particles are categorized into two types: fermions and bosons.
Fermions: Fermions are particles that have half-integer values of spin, such as electrons, quarks, and neutrinos. Fermions obey the Pauli exclusion principle, which states that no two identical fermions can occupy the same quantum state simultaneously.
Bosons: Bosons are particles that have integer values of spin, like photons, W and Z bosons, and the Higgs boson. Bosons can occupy the same quantum state, unlike fermions.
Composite Particles: Composite particles are formed by the combination of elementary particles. Examples include protons and neutrons, which are composed of quarks bound together by the strong nuclear force, and atomic nuclei, which consist of protons and neutrons held together by the same force.
Regarding the second part of your question, the property of charge arises from the presence of electrically charged particles within a particle. Charge is a fundamental property of certain elementary particles, such as electrons and protons. The existence of charge is intimately linked to the electromagnetic force, one of the four fundamental forces of nature.
Charge can be positive or negative. Electrons have a negative charge, while protons have a positive charge. The concept of charge helps to explain the interactions between charged particles through the electromagnetic force. Like charges repel each other, while opposite charges attract. This interaction is mediated by the exchange of photons, which are particles of light and carriers of the electromagnetic force.
The origin of charge is still a topic of ongoing research in physics. It is not fully understood why particles have the specific charges they possess or why some particles are charged while others are neutral. These fundamental questions continue to be investigated in the pursuit of a more comprehensive understanding of the nature of particles and their properties.