[Kr] 5s1
85Rb, 87Rb
2, 8, 18, 8, 1
39.30°C, 102.74°F, 312.45 K
688°C, 1270°F, 961 K
Gustav Kirchhoff and Robert Bunsen
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Uses and Properties

Image Explanation

The red-violet color produced by rubidium fireworks is distinct and can create a visually striking effect in fireworks displays. The characteristic red-violet color of rubidium fireworks is due to the presence of rubidium ions in the flame or explosion, which emit specific wavelengths of light when they are excited.


A soft metal that ignites in the air and reacts violently with water.


Beyond the Laboratory: Exploring the Diverse Uses of Rubidium

Rubidium, an element found in Group 1 of the periodic table, might not be as well-known as some other elements, but its versatility and unique properties make it indispensable in various applications. This unassuming element has found its way into a wide range of industries and technologies, contributing to advancements in fields as diverse as healthcare, electronics, and even fireworks. In this article, we will delve into the exciting and unexpected uses of rubidium that extend far beyond its origins in the laboratory.


The Basics of Rubidium

Before we explore its applications, let's get to know rubidium a little better. Rubidium is a soft, silvery-white alkali metal with the atomic number 37 and the chemical symbol Rb. It is highly reactive and has several isotopes, with Rb-87 being the most abundant and commonly used in various applications.


Atomic Clocks

One of the most precise uses of rubidium can be found in atomic clocks. Atomic clocks are vital for ensuring accurate timekeeping in various technologies, from GPS systems to telecommunications. Rubidium atomic clocks work based on the hyperfine splitting of the ground state of rubidium atoms. This splitting allows for incredibly accurate time measurements, making rubidium clocks a cornerstone of modern timekeeping.



In the field of healthcare, rubidium has found a surprising role. Rubidium-82, a radioactive isotope of rubidium, is used in positron emission tomography (PET) scans. These scans are instrumental in diagnosing various medical conditions, such as heart diseases and certain types of cancer. The short half-life of rubidium-82 makes it ideal for these diagnostic procedures, as it minimizes radiation exposure.



Rubidium's unique properties make it valuable in the field of electronics. Rubidium vapor cells are used in devices known as rubidium frequency standards. These standards provide highly stable and accurate radiofrequency signals, making them essential components in communication systems, including cellular networks and satellite communications.


Fiber Optic Communications

In the world of telecommunications, rubidium also plays a role in ensuring the efficient transmission of data through fiber optic cables. Rubidium gas cells are used in optical communication networks as reference standards for maintaining stable laser frequencies. This stability is crucial for high-speed data transmission and long-distance communication.


Geophysical Exploration

The application of rubidium goes beyond the lab and into the Earth itself. In geophysical exploration, rubidium is used as a tracer element in studying geological processes. Its unique radioactive properties allow scientists to track the movement of fluids in subsurface reservoirs, making it a valuable tool for understanding the Earth's natural resources.



On a more artistic note, rubidium is sometimes used in the creation of stunning red-violet colors in fireworks displays. The rubidium compounds burn with a characteristic red-violet flame, adding an extra layer of visual excitement to the night sky. This use showcases how science and art can combine to create captivating spectacles.


R&D in Fundamental Physics

In the realm of fundamental physics, rubidium is used in experimental setups for studying various phenomena. It is often utilized in Bose-Einstein condensation experiments, helping scientists explore the behavior of ultra-cold atoms and the transition to a unique state of matter at extremely low temperatures. These experiments provide valuable insights into the fundamental laws of physics.



Rubidium, once confined to the laboratory, has found its way into numerous practical applications across different industries. Its unique properties, from precise timekeeping to improving healthcare diagnostics and enabling high-speed data transmission, highlight its versatility. Even in artistic endeavors like fireworks, rubidium's contribution is undeniable. As technology advances and our understanding of this remarkable element deepens, we can only anticipate more innovative uses for rubidium in the future. It's a testament to the endless possibilities that emerge when science and creativity intersect, demonstrating that even the most unassuming elements can play a crucial role in shaping our world.


In the world of elements, Rubidium (Rb) might not be a household name, but its history is a fascinating journey of scientific discovery, innovation, and diverse applications. This unassuming alkali metal, with the atomic number 37, has a rich history dating back to its discovery in the early 19th century. Join us as we embark on a journey through time to explore the remarkable history of Rubidium, from its initial isolation to its modern-day applications across various fields.


The Discovery of Rubidium

The story of Rubidium begins with a Swedish chemist named Carl Gustav Mosander in 1831. Mosander was experimenting with mineral samples containing what we now recognize as Rubidium, although he didn't know it at the time. He was working with a mineral called lepidolite and noticed that it contained a previously unknown element. However, it wasn't until nearly 50 years later that Rubidium was officially discovered.

The honor of officially isolating Rubidium goes to the German chemists Robert Bunsen and Gustav Kirchhoff in 1861. They were conducting spectral analysis on mineral water samples from a spa in Germany, and during their experiments, they noticed two distinct dark lines in the sample's spectrum that didn't correspond to any known element. They realized that these lines indicated the presence of an unknown element. This element was later named Rubidium, derived from the Latin word "rubidus," meaning "dark red," a reference to the ruby-red lines observed in the spectrum.


Early Research and Isolation

The isolation of Rubidium opened up new avenues of scientific exploration. Researchers began to delve into the properties and behavior of this newfound element. Rubidium, like other alkali metals, is highly reactive and was initially isolated through the use of electrolysis. However, it presented numerous challenges due to its extreme reactivity with air and water.

Early studies of Rubidium focused on its physical and chemical properties. It was observed that the element shares many characteristics with other alkali metals, such as sodium and potassium, but it also exhibited unique properties that set it apart.


The 20th Century: Atomic Clocks and Beyond

As the 20th century dawned, Rubidium's significance became increasingly apparent. One of the most notable applications of Rubidium in the mid-20th century was its role in the development of atomic clocks. These incredibly precise timekeeping devices relied on the natural vibrations of Rubidium atoms to maintain accurate time. The transition between the hyperfine energy levels of Rubidium-87 became the basis for Rubidium atomic clocks.

Rubidium atomic clocks offered an unprecedented level of accuracy, making them invaluable for applications in telecommunications, satellite navigation, and various scientific experiments. These clocks could measure time with incredible precision, ensuring synchronized global communication and navigation systems.


Medical and Scientific Applications

Rubidium's applications extended into the medical field. Rubidium-82, a radioactive isotope of Rubidium, has been used in positron emission tomography (PET) scans. These scans are crucial for diagnosing various medical conditions, including heart diseases and certain types of cancer. Rubidium-82 has a short half-life, making it ideal for medical imaging, as it minimizes radiation exposure to patients.

Beyond healthcare, Rubidium has played a significant role in scientific research. It has been used in experiments related to Bose-Einstein condensation, a remarkable state of matter that occurs at extremely low temperatures. Scientists have employed Rubidium to explore the properties of ultra-cold atoms and gain insights into fundamental physics.


Telecommunications and Fiber Optics

Rubidium's influence in the world of telecommunications cannot be overstated. Rubidium vapor cells are used in Rubidium frequency standards, which provide highly stable and accurate radiofrequency signals. These standards are crucial components in communication systems, including cellular networks and satellite communications. The stability of Rubidium-based standards ensures the seamless transmission of data and communication across vast distances.

Rubidium is also used in fiber optic communication networks, where its gas cells serve as reference standards for maintaining stable laser frequencies. This stability is essential for high-speed data transmission and long-distance communication, making Rubidium a critical element in the digital age.


Geophysical Exploration

Rubidium's versatile applications extend below the Earth's surface as well. In geophysical exploration, Rubidium serves as a tracer element in the study of geological processes. Its unique radioactive properties enable scientists to track the movement of fluids in subsurface reservoirs, aiding in the understanding of natural resources and environmental phenomena.


The history of Rubidium is a testament to the remarkable journey of a once-unknown element from discovery to diverse applications in various fields. From its early isolation by Bunsen and Kirchhoff to its vital role in atomic clocks, telecommunications, healthcare, and geophysical exploration, Rubidium has proven its worth as an indispensable element. As technology advances and our understanding of this remarkable element deepens, we can only anticipate more innovative applications for Rubidium in the future. It is a testament to the power of scientific exploration and innovation that even the most unassuming elements can play a pivotal role in shaping our world. Rubidium's history is a story of scientific curiosity, discovery, and the continuous pursuit of knowledge.

Atomic Data

Atomic Radiues, Non-bonded (A): 3.03
Electron Affinity (kJ mol-1): 46.884
Covalent Radiues (A): 2.15
Electronegativity (Pauling Scale): 0.82
Ionisation Energies (kJ mol-1) 1st 2nd 3rd 4th 5th 6th 7th 8th
403.032 2633.037 3859 5075.1 6850 8143.4 9571.3 13122

Oxidation States and Isotopes

Common oxidation states 1
Isotope Atomic Mass Natural Abundance Half Life Mode of Decay
85Rb 84.912 72.17 - -
87Rb 86.909 27.83 4.88 x 1010 y β-

Supply Risk

Relative Supply Risk: Unknown
Crustal Abundance (ppm): 90
Recycle Rate (%): Unknown
Production Conc.(%) : Unknown
Top 3 Producers:
Top 3 Reserve Holders:
Substitutability: Unknown
Political Stability of Top Producer: Unknown
Political Stability of Top Reserve Holder: Unknown

Pressure and Temperature Data

Specific Heat Capacity: 363
Shear Modulus: Unknown
Young Modulus: Unknown
Bulk Modulus: 2.5
Pressure 400k Pressure 600k Pressure 800k Pressure 1000k Pressure 1200k Pressure 1400k Pressure 1600k Pressure 1800k Pressure 2000k Pressure 2200k Pressure 2400k
0.165 - - - - - - - - - 2.5


Transcript :

Rubidium is an element in Group 1 of the periodic table. It is one of the alkali metals and is the 37th element on the periodic table and its name derives from the Latin word Rubidus, meaning "deep red". Rubidium atoms are arranged in a cubic close-packed structure. Each Rubidium atom has only one electron in the outermost energy level. This element is an amalgam of two isotopes, Rubidium 87 and Rubidium 85.

Rubidium's chemistry is similar to that of other group 1 metals. It is very similar to potassium. They have the same chemical properties. In fact, both are grouped together in the alkali metals group. In the natural environment, Rubidium consists of two isotopes. One is naturally present in seawater, while the other is found in lithium chlorides. When Rubidium is dissolved in water, it forms a compound known as Rubidium hydroxide. This later, is a strong alkali and must be handled with great care. To prevent a reaction, the element must be stored in an inert gas atmosphere. It is important to store it under a dry mineral oil. When a piece of Rubidium is exposed to air, it will ignite. The element can also react with mercury and potassium.

Rubidium was discovered in 1861 by German chemists: Gustav Kirchhoff and Robert Bunsen. They isolated samples of the new metal using electrolysis. Since then, it has played a major role in research.

Rubidium is one of the rarest metals in the world. It is found in only a handful of places on the Earth. This element occurs naturally in igneous rocks, seawater, spring waters, and brines. This element is also present in trace amounts in other minerals and it is often found in mixtures with other alkali metals. This mixture is often called lepidolite. It contains around 3.5 percent of Rubidium, making it the primary source of this metal in the world. Pollucite is another mineral which contains this element together with other such as Aluminum and Silicon. In addition, Rubidium is present in trace amounts in many other minerals. In the Earth's crust, the amount of Rubidium is about 90 parts per million by weight.

The occurrence and production of Rubidium has increased in the past few years. Currently, most Rubidium is obtained as a byproduct of refining lithium. It is produced by electrolysis. During the process, it is mixed with other alkali metals to create an alloy. This is the process by which the metal becomes a commercially available product.

Rubidium is the second most electropositive of the stable alkali metals. It is a very soft metallic element. It has a density of approximately 90 parts per million. Like potassium, this element is very reactive. This makes it a good heat conductor. Rubidium is also the first alkali metal to have a density that is greater than that of water. They also have a good ionization property, which makes them ideal for the manufacture of photoelectric cells. Rubidium has a higher ionic radius.

It oxidizes easily with water, reacting violently.

When dissolved in water, Rubidium is almost always in the +1 oxidation state. However, it does form peroxides when exposed to air. That is why this element is important to keep in a dry mineral oil. In addition, it is highly susceptible to fire. When a piece of Rubidium is exposed to air, it will ignite. The element can also react with mercury and potassium.

Although Rubidium has many applications in the industry, it has not been used extensively. In fact, its use was much lower in the 1920s, Rubidium was used in the manufacture of atomic clocks, photocells, and vacuum tubes. It is also a component of special types of glass.

Although Rubidium is not used in many industrial applications, this element is considered a valuable element for research purposes. Rubidium can be used to remove gases from vacuum tubes. Some of its uses include laser cooling and Bose-Einstein condensation. The element has also been used in ion engines which is a form of electric propulsion used for spacecraft propulsion. However, it known that Rubidium not as effective as Cesium in these types of engines.

Its use in thin film batteries is another application taking profit from this element. Compared with lithium, its half-life is longer. Furthermore, it may be used in ion thrusters.


  • W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.

  • Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.

  • J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.

  • T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.

  • John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.

  • Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.