The number of atoms is 2
To determine the number of atoms, we need to first know that atoms are described as the smallest particle of a chemical element.
The different types of particles are;
Protons
Electrons
Neutrons.
The defining particle that identifies an atom is the number of protons it contains.
Neutrons and protons have same mass and in contrast to this the mass of an electron is negligible.
A proton carries a positive charge, a neutron has no charge and an electron is negatively charged.