Final answer:
Oxygen has an atomic number of 8, meaning it has 8 protons. Its three stable isotopes, oxygen-16, oxygen-17, and oxygen-18, have 8, 9, and 10 neutrons respectively, found by subtracting the number of protons from the mass numbers. The majority of naturally occurring oxygen is oxygen-16, with other isotopes presenting in much smaller amounts.
Step-by-step explanation:
Oxygen, which is represented by the symbol O on the periodic table, has an atomic number of 8. This atomic number tells us that oxygen has 8 protons. Regarding the isotopes of oxygen, there are three stable ones: oxygen-16, oxygen-17, and oxygen-18. The numbers 16, 17, and 18 represent the mass numbers (A) for each isotope, which is the sum of protons (denoted as Z) and neutrons in the nucleus.
To find the number of neutrons in each isotope, we subtract the number of protons (Z) from the mass number (A). For oxygen-16, A (16) - Z (8) equals 8 neutrons. For oxygen-17, A (17) - Z (8) equals 9 neutrons. And for oxygen-18, A (18) - Z (8) equals 10 neutrons. The overwhelming majority of naturally occurring oxygen is in the form of oxygen-16, with about 99.76% abundance.
These different isotopes occur due to variations in the number of neutrons, while the number of protons remains constant within an element, adhering to the definition of isotopes. While oxygen-16, oxygen-17, and oxygen-18 are stable and do not exhibit radioactivity, other isotopes that are unstable become radioisotopes and can emit radiation as a result of decaying processes.