What is the Difference Between Radon and Radium

The main difference between radon and radium is that radon is a colorless, odorless, and tasteless radioactive noble gas, whereas radium is a radioactive alkaline earth metal.

Radon and radium, two radioactive elements, have played pivotal roles in the understanding of radiation’s effects on human health and the environment.

Key Areas Covered

1. What is Radon 
      – Definition, Features 
2. What is Radium
      – Definition, Features 
3. Similarities Between Radon and Radium
      – Outline of Common Features
4. Difference Between Radon and Radium
      – Comparison of Key Differences
5. FAQ: Radon and Radium
      – Frequently Asked Questions

Key Terms

Ra, Radon, Radon-222, RadiumDifference Between Radon and Radium - Comparison Summary

What is Radon

Radon is a noble gas and is a part of the decay chain of uranium, which is found in many rocks and soils. It’s a radioactive gas, which means it decays and emits particles. The primary radon isotopes of concern are radon-222 and radon-220, also known as thoron. Radon-222 is the most common and is the one typically associated with indoor radon exposure. Radon is formed by the radioactive decay of uranium-238, which is a common element in the Earth’s crust. Uranium-238 slowly decays into radium-226, which, in turn, decays into radon-222. Radon is a gas, and it can move through the soil and enter buildings through cracks, gaps, and other openings. Homes built on soil with high concentrations of uranium are more likely to have elevated radon levels.

Radon can infiltrate buildings through various pathways. It can seep through cracks in the foundation, enter through gaps around pipes, cables, and utility penetrations, navigate through cavities inside walls, and find its way through sump pumps and floor drains. Additionally, construction joints where different building parts meet can provide an entry point for radon.

Radon vs Radium

Radon’s Effect on Health and Environment

Radon is a known human carcinogen, and long-term exposure to elevated radon levels is associated with an increased risk of lung cancer. There is no safe level of radon exposure, and reducing radon levels in indoor air is crucial to minimize these health risks. While radon itself doesn’t have advantages, addressing radon in indoor air offers the advantage of reducing the risk of lung cancer. By testing for radon and implementing mitigation measures when necessary, individuals can take proactive steps to protect their health. The presence of radon in indoor air has led to increased awareness and education about the importance of indoor air quality. This, in turn, has spurred research and technological advancements in radon detection and mitigation.

What is Radium

Radium, element 88 with the symbol Ra, has a fascinating but cautionary history. Initially celebrated for its mysterious glow and potential medicinal uses, radium’s radioactive properties were soon recognized as a serious health hazard. The infamous case of the Radium Girls, who painted watch dials with radium-based paint, revealed the dire consequences of radium exposure, including radiation burns, anemia, and cancers. Radium emits harmful alpha, beta, and gamma radiation, particularly damaging when ingested or inhaled due to its heavy, positively charged alpha particles.

Compare Radon and Radium

These tragic events prompted extensive research into radium’s effects, leading to a better understanding of radiation’s risks. Radium was once used in medical treatments, especially for cancer, relying on its radiation to target cancer cells. However, its side effects, like radiation burns, led to controversy, and safer radiation therapies, such as X-ray therapy, were developed, causing radium therapy to fall out of favor in medical practice.

Similarities Between Radon and Radium

  • They are both radioactive metals.
  • Both radon and radium are naturally occurring elements found in the Earth’s crust.
  • Both elements are associated with health risks.

Difference Between Radon and Radium


Radon is a colorless, odorless, and tasteless radioactive noble gas, whereas radium is a radioactive alkaline earth metal.


While radon has the symbol Rn and atomic number 86, radium has the symbol Ra and atomic number 88.


Radon is a gas at room temperature and pressure, while radium is a solid metal at room temperature.


Radon is not typically used for specific applications but is a concern for indoor air quality. Radium was historically used in various applications, including luminescent paint for watch dials, radium-infused health products, and radium therapy in medicine.

FAQ: Radon and Radium

Are radon and radium the same?

No, radon and radium are not the same. They are two different radioactive elements. Radon is a colorless, odorless, radioactive gas with the symbol Rn and atomic number 86. Radium, on the other hand, is a radioactive element with the symbol Ra and atomic number 88.

What is more radioactive: radon or radium?

Radium is more radioactive than radon. Radium is a solid radioactive element with a higher level of radioactivity, emitting alpha, beta, and gamma radiation.

Is radium highly toxic?

Yes, radium is highly toxic. It is a radioactive element that poses significant health risks, particularly when ingested, inhaled, or if it comes into contact with living tissues. The harmful effects of radium exposure include severe radiation burns, anemia, and an increased risk of cancer.


The main difference between radon and radium is that radon is a colorless, odorless, and tasteless radioactive noble gas, whereas radium is a radioactive alkaline earth metal.


1. “Radon.” Wikipedia. Wikipedia Foundation.
2. “Radium” Science Direct.

Image Courtesy:

1. “Decay chain(4n+2,_Uranium_series)” By User: Tosaka – File:Decay chain(4n+2, Uranium series).PNG (CC BY 3.0) via Commons Wikimedia
2. “Radium 2” By Mauswiesel – Own work (CC BY-SA 3.0) via Commons Wikimedia

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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