Answer:
An atom is the smallest particle of a chemical element that can exist.
Step-by-step explanation:
The elements like Oxygen, Sodium or Hydrogen are atoms with a specific number of protons in its nucleus, which is equal to the number of electrons in its orbitals; for example, an atom with 8 protons and 8 electrons is an atom of oxygen (the number of neutrons changes from isotope to isotope)