Oxygen's atomic number is indeed 8, which means that it has 8 protons in its nucleus. However, the mass number of an atom is the total number of protons and neutrons in the nucleus.
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Mass Number: The mass number of oxygen is typically around 16 for the most common isotope (O-16), which has 8 protons and 8 neutrons. So, the mass number is not necessarily equal to the atomic number.
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Neutrons: A typical oxygen atom has 8 neutrons in the most abundant isotope, O-16.
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Protons: As you stated, there are indeed 8 protons in an oxygen atom.
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Electrons: In a neutral oxygen atom, there are also 8 electrons to balance the 8 protons.
In summary, an oxygen atom with atomic number 8 has:
- 8 protons
- 8 electrons
- 8 neutrons (in the most common isotope, O-16)
- A mass number of 16
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