radium-228

chemical isotope

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July 19, 2026

Quick Summary

Radium-228 is a radioactive isotope of radium, which is the heaviest of the alkaline-earth metals. It is not found freely in nature but is a product of radioactive decay series, specifically the thorium series. Radium-228 has a half-life of 5.75 years.1

When radium-228 decays, it emits alpha particles, which are heavy and highly ionizing. Due to their limited penetration, alpha particles primarily affect tissues in their immediate vicinity, often leading to tumors at the site of storage. Radium isotopes, due to their chemical similarity to calcium, tend to accumulate in bones. This can cause abnormal changes in bone marrow, leading to conditions like anemia and leukemia, as well as bone cancers.2

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radium
Occurrence, properties, and uses
…for radium-226 (1,600 years) and radium-228 (5.75 years), are less than a few weeks. The long-lived radium-226 is found in nature as a result of its continuous formation from uranium-238 decay. Radium thus occurs in all uranium ores, but it is more widely distributed because it forms water-soluble compounds; Earth’s…
Read More
…for radium-226 (1,600 years) and radium-228 (5.75 years), are less than a few weeks. The long-lived radium-226 is found in nature as a result of its continuous formation from uranium-238 decay. Radium thus occurs in all uranium ores, but it is more widely distributed because it forms water-soluble compounds; Earth’s…
Read More