Protons: Found in the nucleus (the center) of the atom, protons have a positive charge.

Neutrons: Also located in the nucleus, neutrons have no charge (neutral). They help add mass to the atom and stabilize the nucleus.

Electrons: These are negatively charged particles that orbit the nucleus in various energy levels or shells.

Atomic number: The number of protons in an atom, which defines the element.

For example, hydrogen has 1 proton, helium has 2, and so on.

Mass number: The sum of protons and neutrons in the nucleus.

Isotopes: Atoms of the same element can have different numbers of neutrons, leading to different isotopes of that element.

Atoms combine to form molecules, and their interactions drive much of chemistry and physical processes. The behavior of electrons, especially their arrangement in electron shells, is central to how atoms bond and interact with one another.