What is an a1 atom in chemistry.

Atomic Electron Configurations.

An atom is the smallest particle of a chemical element that can exist.

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)