* Protons: Positively charged particles found in the nucleus of the atom.

* Neutrons: Neutrally charged particles also found in the nucleus of the atom.

* Electrons: Negatively charged particles that orbit the nucleus in a cloud-like region called the electron cloud.

Here's a breakdown of their key roles:

* Protons and neutrons determine the atomic mass of an atom. The number of protons defines the atomic number of an element, which is unique to each element on the periodic table.

* Electrons determine the chemical properties of an atom. They are involved in chemical bonding and interactions with other atoms.

There are also other subatomic particles, such as quarks, gluons, and bosons, which are involved in more complex nuclear physics and particle physics. However, for a basic understanding of the atom, protons, neutrons, and electrons are the primary particles to focus on.