No, the atomic number of O2 and O is not the same.
The atomic number represents the number of protons in the nucleus of an atom. For oxygen (O), the atomic number is 8. This means that an oxygen atom has 8 protons in its nucleus.
On the other hand, "O2" refers to a molecule of oxygen, specifically molecular oxygen. In a molecule of O2, two oxygen atoms are chemically bonded together. The molecular formula "O2" indicates that the molecule consists of two oxygen atoms.
While the atomic number of an individual oxygen atom remains 8, the molecular formula "O2" is used to represent the diatomic molecule, which contains two oxygen atoms bonded together.