An atom is the basic unit of matter that makes up all elements. It is the smallest particle of an element that still retains the properties of that element.
An atom is composed of a nucleus, which contains protons and neutrons, and electrons that orbit around the nucleus.
Atoms of different elements have a different number of protons in their nucleus, which determines the element. They may also have different numbers of neutrons and electrons.
The atomic number of an element is the number of protons in its nucleus, and it determines the element's properties. Atoms with the same atomic number belong to the same element.
Atoms combine with each other through chemical bonds to form compounds. These bonds can be ionic, covalent, or metallic. The type of bond depends on the elements involved and their electron configurations.