The mass of an individual atom of oxygen (O) is typically expressed in atomic mass units (u) rather than grams. However, I can provide you with the approximate atomic mass of oxygen and then convert it to grams for you.
The atomic mass of oxygen (O) is approximately 16.00 atomic mass units (u). To convert this to grams, you can use the fact that 1 atomic mass unit is equal to 1.66 x 10^-24 grams.
Therefore, the mass of an oxygen atom in grams is approximately: 16.00 u * (1.66 x 10^-24 g/u) ≈ 2.656 x 10^-23 grams.
Please note that this value is an approximation and can vary slightly depending on the isotope of oxygen considered.