An atom is the smallest unit to break an element into without losing its chemical identity. Atoms consist of a large central nucleus surrounded by a swarm of electrons or negatively charged particles. The nucleus comprises both positive (protons) particles and electrically neutral (neutrons) particles. The number of protons is called the number of atoms. This number describes each chemical element in its own special way. The protons and neutrons in fact consist of quarks.
An element is a chemical material consisting of a single form of atom. A molecule is formed when two or more atoms of some kind of material are chemically bound together. If there are two or more distinct elements in a molecule that is known as a compound. A water molecule is a combination of the hydrogen and oxygen components.
If an atom or molecule is charged electrically by acquiring or losing one or two electrons, then it becomes an ion. This has a negative charge if the atom absorbs electrons. It has a positive charge, as it lacks electrons.