Isotopes of oxygen

Isotopes of Oxygen

Diagram showing fusion shells in evolved stars, where isotopes of oxygen can be formed.

Oxygen is a chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table and is a highly reactive nonmetal. Oxygen forms compounds with almost all other elements and is essential for life as we know it. The element has several isotopes, which are variants of the element that differ in the number of neutrons in their nuclei.

Stable Isotopes

Oxygen has three stable isotopes: oxygen-16, oxygen-17, and oxygen-18.

• Oxygen-16 (\(^{16}\text{O}\)) is the most abundant isotope, making up about 99.76% of the oxygen in nature. It has 8 protons and 8 neutrons.
• Oxygen-17 (\(^{17}\text{O}\)) is a rare isotope, constituting about 0.04% of natural oxygen. It has 8 protons and 9 neutrons.
• Oxygen-18 (\(^{18}\text{O}\)) makes up about 0.20% of natural oxygen. It has 8 protons and 10 neutrons.

These isotopes are stable and do not undergo radioactive decay.

Radioactive Isotopes

Oxygen also has several radioactive isotopes, which are not stable and decay over time. The most notable radioactive isotopes include:

• Oxygen-15 (\(^{15}\text{O}\)) has a half-life of about 122 seconds and is used in positron emission tomography (PET) imaging.
• Oxygen-19 (\(^{19}\text{O}\)) has a half-life of about 26.9 seconds.

These isotopes are typically produced in particle accelerators or during certain types of nuclear reactions.

Formation in Stars

Oxygen isotopes are formed in the interiors of stars through nuclear fusion processes. In massive stars, oxygen is produced during the helium burning phase, where helium nuclei fuse to form carbon, which can further capture helium to form oxygen. The diagram on the right illustrates the fusion shells in evolved stars, where isotopes of oxygen can be formed.

Applications

The different isotopes of oxygen have various applications in science and industry:

• Oxygen-18 is used in paleoclimatology to study past climates by analyzing ice cores and sediment layers.
• Oxygen-15 is used in medical imaging techniques such as PET scans to study brain and heart function.

Related Pages

• Oxygen
• Isotope
• Nuclear fusion
• Star
• Periodic table