86
Rn
Radon

Radon

Element 86 • Noble Gas
Atomic Mass 222.000000
Electron Config [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶
Group/Period 18/6

Overview

ANALYZED
Radon is a radioactive noble gas that can accumulate in buildings.

Physical Properties

MEASURED
Atomic Mass
222.000000 u
Density
0.0097 g/cm³
Melting Point
202.00 °C
Boiling Point
211.30 °C
Electronegativity
2.20
Electron Configuration
[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶
Ionization Energy
10.75 kJ/mol

Special Properties

CLASSIFIED
RADIOACTIVE This element emits radiation
INERT Chemically stable and unreactive
Earth Abundance: 0.00e+0
Universe Abundance: 0.00e+0

Applications

CATALOGUED

Medical Applications (Historical)

Historically, Radon was used in "Radon therapy" from the 1920s through 1950s, where patients were exposed to Radon gas or radioactive water containing Radon for treating arthritis, hypertension, and other ailments. These treatments, now known to be extremely

dangerous, were based on the misguided belief that small amounts of radiation were beneficial.
Today, Radon-222 is still occasionally used in very controlled medical research to study lung cancer mechanisms and test radiation protection methods.

Scientific Research Tools

Radon serves as a valuable tracer in atmospheric and geological research. Scientists use Radon concentrations to study air mass movements, track pollution dispersion, and understand groundwater flow patterns. Radon-222 acts as a natural "fingerprint" for identifying air masses and studying atmospheric mixing processes. Its decay products help researchers understand particle physics and test radiation detection equipment.

Indoor Air Quality Indicator

Radon measurement has become a crucial tool in public health and real estate. Professional Radon testing services use specialized detectors to measure Radon concentrations in homes, schools, and workplaces. This application has created an entire industry focused on Radon detection, mitigation, and prevention, protecting millions of people from this invisible health hazard.

Educational and Training

Controlled Radon sources are used to train radiation safety professionals, health physicists, and environmental scientists. These applications help develop and test Radon detection equipment, calibrate monitoring instruments, and research new mitigation techniques. Radon also serves as a model system for studying the behavior of other radioactive gases in the environment.

Common Uses

INDEXED

Radon Testing Services

The most common modern use of Radon technology involves professional testing services that help homeowners and businesses identify

dangerous Radon levels.
Short-term tests (2-90 days) and long-term tests (over 90 days) use activated charcoal detectors, alpha track detectors, or electronic continuous monitors to measure Radon concentrations. This industry employs thousands of certified professionals and generates hundreds of millions in annual revenue while protecting public health.

Mitigation System Design

Understanding Radon behavior drives the design of mitigation systems including sub-slab depressurization, crawl space ventilation, and air exchange systems. Engineers use Radon source modeling to design effective systems that reduce indoor concentrations below EPA action levels (4 pCi/L). These systems protect millions of homes and are required by building codes in many high-Radon areas.

Environmental Monitoring

Government agencies and research institutions use Radon monitoring networks to track environmental trends, study climate change effects, and identify geological hazards. Continuous Radon monitoring helps predict earthquakes in some regions, as ground movement can alter Radon emission patterns. These applications contribute to both public safety and scientific understanding of Earth processes.

No Commercial Products

Unlike historical uses, Radon is no longer used in consumer products due to its severe health risks. Former applications included luminous paint for watch dials and instrument panels (discontinued in the 1960s) and therapeutic devices (banned for safety reasons). Today, any commercial use of Radon is highly regulated and limited to specialized research applications in controlled environments.

Natural Occurrence

SURVEYED

Ubiquitous Indoor Presence

Radon occurs naturally in virtually every building on Earth, originating from the radioactive decay of uranium-238 present in soil, rock, and building materials. Concentrations vary dramatically based on local geology, with particularly high levels in areas with granite bedrock, phosphate deposits, or uranium-rich soils. The EPA estimates that 1 in 15 U.S. homes has elevated Radon levels, making it the second leading cause of lung cancer after smoking.

Geological Sources

Radon-222 forms continuously in the uranium decay chain, starting with uranium-238 in rocks and soil. High-Radon areas include the Reading Prong (Pennsylvania, New Jersey, New York), parts of Colorado, Iowa, and North Dakota. Radon can also originate from well water, particularly in areas with granite bedrock or uranium-rich aquifers. Some building materials, including concrete made with uranium-bearing aggregate, can be significant indoor Radon sources.

Atmospheric Distribution

Outdoor Radon concentrations are typically low (0.1-0.4 pCi/L) due to atmospheric dilution, but indoor levels can be 10-100 times higher due to accumulation in enclosed spaces. Radon enters buildings through foundation cracks, sump pumps, floor drains, and gaps around pipes. Weather conditions, soil moisture, and barometric pressure changes significantly affect Radon entry rates and indoor concentrations.

Water Sources

Radon dissolves readily in groundwater, particularly in areas with uranium-bearing bedrock. When Radon-contaminated water is used for showering, washing, or drinking, the gas can be released into indoor air or ingested directly. The EPA estimates that Radon in water causes about 168 deaths annually, with the highest risks in private wells drawing from granite or uranium-rich aquifers.

Discovery

ARCHIVED
1900

Friedrich Ernst Dorn (1900)

Radon was discovered in 1900 by German physicist Friedrich Ernst Dorn at the University of Halle, while studying the radioactive decay of radium. Dorn observed that radium samples continuously produced a radioactive gas that he initially called "radium emanation." This discovery was part of the early radiation research that followed Henri Becquerels discovery of radioactivity in 1896 and Marie and Pierre Curies work with radium.

Early Characterization

Following Dorns initial discovery, scientists William Ramsay and Robert Whytlaw-Gray isolated radon in 1910 and determined its atomic weight, confirming it as a noble gas. They measured its density and found it to be the heaviest known gas at the time. The element was initially called "niton" (from Latin "nitens," meaning shining) due to its luminescent properties, but was renamed "radon" in 1923.

Commercial Exploitation Era

In the early 1900s, radon was considered valuable for its supposed therapeutic properties. Entrepreneurs established "radon spas" and marketed radon-infused water as health tonics. The discovery that radon could make materials luminescent led to its use in self-luminous paint for watch dials and instrument panels, an application that continued until the health risks became apparent in the 1960s.

Health Hazard Recognition

The understanding of radons danger evolved slowly. Lung cancer rates among uranium miners were noted as early as the 1500s, but the connection to radon wasnt established until the 1950s. Comprehensive studies of radon health effects began in the 1970s, leading to the recognition of radon as a major public health threat and the development of modern testing and mitigation programs in the 1980s.

Safety Information

CRITICAL

Leading Cause of Lung Cancer

Radon is the second leading cause of lung cancer in the United States, responsible for approximately 21,000 deaths annually. When inhaled, Radon decay products (polonium-218 and polonium-214) attach to lung tissue and emit alpha radiation, causing DNA damage that can lead to cancer. The risk increases dramatically for smokers, as tobacco smoke and Radon exposure have synergistic effects on lung cancer development.

Indoor Air Quality Threat

The EPA recommends testing all homes for Radon, as levels can vary dramatically even between neighboring houses. Radon concentrations above 4 pCi/L require mitigation, though no level is considered completely safe. Children are at higher risk due to their higher breathing rates and longer expected lifespans. Schools and workplaces should also be tested regularly.

Mitigation Strategies

Effective Radon mitigation includes sub-slab depressurization systems, improved ventilation, and sealing foundation cracks. Professional installation is recommended, as improper mitigation can actually increase Radon levels. Post-mitigation testing is essential to verify system effectiveness. Homeowners should also test water supplies, particularly private wells, as Radon can be released during showering and washing.

Continuous Monitoring Recommended

Radon levels fluctuate seasonally and daily due to weather conditions, soil moisture, and barometric pressure changes. Long-term testing (over 90 days) provides the most accurate assessment of average exposure. Electronic continuous monitors can track daily variations and help identify factors that influence Radon entry. Regular retesting every 2-5 years is recommended, especially after home renovations.

Knowledge Database

Essential information about Radon (Rn)

Radon is unique due to its atomic number of 86 and belongs to the Noble Gas category. With an atomic mass of 222.000000, it exhibits distinctive properties that make it valuable for various applications.

Its electron configuration ([Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶) determines its chemical behavior and bonding patterns.

Radon has several important physical properties:

Density: 0.0097 g/cm³

Melting Point: 202.00 K (-71°C)

Boiling Point: 211.30 K (-62°C)

State at Room Temperature: Gas

Atomic Radius: 150 pm

Radon has various important applications in modern technology and industry:

Medical Applications (Historical)

Historically, Radon was used in "Radon therapy" from the 1920s through 1950s, where patients were exposed to Radon gas or radioactive water containing Radon for treating arthritis, hypertension, and other ailments. These treatments, now known to be extremely

dangerous, were based on the misguided belief that small amounts of radiation were beneficial.
Today, Radon-222 is still occasionally used in very controlled medical research to study lung cancer mechanisms and test radiation protection methods.

Scientific Research Tools

Radon serves as a valuable tracer in atmospheric and geological research. Scientists use Radon concentrations to study air mass movements, track pollution dispersion, and understand groundwater flow patterns. Radon-222 acts as a natural "fingerprint" for identifying air masses and studying atmospheric mixing processes. Its decay products help researchers understand particle physics and test radiation detection equipment.

Indoor Air Quality Indicator

Radon measurement has become a crucial tool in public health and real estate. Professional Radon testing services use specialized detectors to measure Radon concentrations in homes, schools, and workplaces. This application has created an entire industry focused on Radon detection, mitigation, and prevention, protecting millions of people from this invisible health hazard.

Educational and Training

Controlled Radon sources are used to train radiation safety professionals, health physicists, and environmental scientists. These applications help develop and test Radon detection equipment, calibrate monitoring instruments, and research new mitigation techniques. Radon also serves as a model system for studying the behavior of other radioactive gases in the environment.

1900

Friedrich Ernst Dorn (1900)

Radon was discovered in 1900 by German physicist Friedrich Ernst Dorn at the University of Halle, while studying the radioactive decay of radium. Dorn observed that radium samples continuously produced a radioactive gas that he initially called "radium emanation." This discovery was part of the early radiation research that followed Henri Becquerels discovery of radioactivity in 1896 and Marie and Pierre Curies work with radium.

Early Characterization

Following Dorns initial discovery, scientists William Ramsay and Robert Whytlaw-Gray isolated radon in 1910 and determined its atomic weight, confirming it as a noble gas. They measured its density and found it to be the heaviest known gas at the time. The element was initially called "niton" (from Latin "nitens," meaning shining) due to its luminescent properties, but was renamed "radon" in 1923.

Commercial Exploitation Era

In the early 1900s, radon was considered valuable for its supposed therapeutic properties. Entrepreneurs established "radon spas" and marketed radon-infused water as health tonics. The discovery that radon could make materials luminescent led to its use in self-luminous paint for watch dials and instrument panels, an application that continued until the health risks became apparent in the 1960s.

Health Hazard Recognition

The understanding of radons danger evolved slowly. Lung cancer rates among uranium miners were noted as early as the 1500s, but the connection to radon wasnt established until the 1950s. Comprehensive studies of radon health effects began in the 1970s, leading to the recognition of radon as a major public health threat and the development of modern testing and mitigation programs in the 1980s.

Discovered by: <div class="discovery-content"> <h3><i class="fas fa-user-graduate"></i> Friedrich Ernst Dorn (1900)</h3> <p>Radon was discovered in 1900 by German physicist Friedrich Ernst Dorn at the University of Halle, while studying the radioactive decay of radium. Dorn observed that radium samples continuously produced a radioactive gas that he initially called "radium emanation." This discovery was part of the early radiation research that followed Henri Becquerels discovery of radioactivity in 1896 and Marie and Pierre Curies work with radium.</p> <h3><i class="fas fa-flask"></i> Early Characterization</h3> <p>Following Dorns initial discovery, scientists William Ramsay and Robert Whytlaw-Gray isolated radon in 1910 and determined its atomic weight, confirming it as a noble gas. They measured its density and found it to be the heaviest known gas at the time. The element was initially called "niton" (from Latin "nitens," meaning shining) due to its luminescent properties, but was renamed "radon" in 1923.</p> <h3><i class="fas fa-lightbulb"></i> Commercial Exploitation Era</h3> <p>In the early 1900s, radon was considered valuable for its supposed therapeutic properties. Entrepreneurs established "radon spas" and marketed radon-infused water as health tonics. The discovery that radon could make materials luminescent led to its use in self-luminous paint for watch dials and instrument panels, an application that continued until the health risks became apparent in the 1960s.</p> <h3><i class="fas fa-exclamation-triangle"></i> Health Hazard Recognition</h3> <p>The understanding of radons danger evolved slowly. Lung cancer rates among uranium miners were noted as early as the 1500s, but the connection to radon wasnt established until the 1950s. Comprehensive studies of radon health effects began in the 1970s, leading to the recognition of radon as a major public health threat and the development of modern testing and mitigation programs in the 1980s.</p> </div>

Year of Discovery: 1900

Ubiquitous Indoor Presence

Radon occurs naturally in virtually every building on Earth, originating from the radioactive decay of uranium-238 present in soil, rock, and building materials. Concentrations vary dramatically based on local geology, with particularly high levels in areas with granite bedrock, phosphate deposits, or uranium-rich soils. The EPA estimates that 1 in 15 U.S. homes has elevated Radon levels, making it the second leading cause of lung cancer after smoking.

Geological Sources

Radon-222 forms continuously in the uranium decay chain, starting with uranium-238 in rocks and soil. High-Radon areas include the Reading Prong (Pennsylvania, New Jersey, New York), parts of Colorado, Iowa, and North Dakota. Radon can also originate from well water, particularly in areas with granite bedrock or uranium-rich aquifers. Some building materials, including concrete made with uranium-bearing aggregate, can be significant indoor Radon sources.

Atmospheric Distribution

Outdoor Radon concentrations are typically low (0.1-0.4 pCi/L) due to atmospheric dilution, but indoor levels can be 10-100 times higher due to accumulation in enclosed spaces. Radon enters buildings through foundation cracks, sump pumps, floor drains, and gaps around pipes. Weather conditions, soil moisture, and barometric pressure changes significantly affect Radon entry rates and indoor concentrations.

Water Sources

Radon dissolves readily in groundwater, particularly in areas with uranium-bearing bedrock. When Radon-contaminated water is used for showering, washing, or drinking, the gas can be released into indoor air or ingested directly. The EPA estimates that Radon in water causes about 168 deaths annually, with the highest risks in private wells drawing from granite or uranium-rich aquifers.

Earth's Abundance: 0.00e+0

Universe Abundance: 0.00e+0

⚠️ Caution: Radon is radioactive and requires special handling procedures. Only trained professionals should work with this element.

Leading Cause of Lung Cancer

Radon is the second leading cause of lung cancer in the United States, responsible for approximately 21,000 deaths annually. When inhaled, Radon decay products (polonium-218 and polonium-214) attach to lung tissue and emit alpha radiation, causing DNA damage that can lead to cancer. The risk increases dramatically for smokers, as tobacco smoke and Radon exposure have synergistic effects on lung cancer development.

Indoor Air Quality Threat

The EPA recommends testing all homes for Radon, as levels can vary dramatically even between neighboring houses. Radon concentrations above 4 pCi/L require mitigation, though no level is considered completely safe. Children are at higher risk due to their higher breathing rates and longer expected lifespans. Schools and workplaces should also be tested regularly.

Mitigation Strategies

Effective Radon mitigation includes sub-slab depressurization systems, improved ventilation, and sealing foundation cracks. Professional installation is recommended, as improper mitigation can actually increase Radon levels. Post-mitigation testing is essential to verify system effectiveness. Homeowners should also test water supplies, particularly private wells, as Radon can be released during showering and washing.

Continuous Monitoring Recommended

Radon levels fluctuate seasonally and daily due to weather conditions, soil moisture, and barometric pressure changes. Long-term testing (over 90 days) provides the most accurate assessment of average exposure. Electronic continuous monitors can track daily variations and help identify factors that influence Radon entry. Regular retesting every 2-5 years is recommended, especially after home renovations.

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