Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of an oxygen atom?

Question

Quizplus · Accepted Answer

The atomic mass of an atom is equal to the number of protons and neutrons in the nucleus of the atom. Oxygen has 8 protons, but the mass number of 16 is the sum of the protons and neutrons. Therefore, the number of neutrons in oxygen is 16 - 8 = 8. The atomic mass is calculated by taking a weighted average of the isotopes, based on their abundance in nature. Oxygen has three stable isotopes: oxygen-16, oxygen-17, and oxygen-18. Oxygen-16 is by far the most abundant, comprising about 99.76% of all oxygen atoms. Therefore, the atomic mass of an oxygen atom is approximately 16 daltons.

Oxygen Has an Atomic Number of 8 and a Mass