The Radiant Element Rubidium

Introduction to Rubidium

Rubidium is a soft metal with silver color. However, rubidium can turn to a liquid at temperature of 38.9°C (104°F). Rubidium is also an extremely reactive element, which can make it hard to have practical applications. However, it is used in ceramics, in molecular biology, and even in the potential creation of space vehicles!

10 Fun Facts about Rubidium

  • When burned, rubidium gives off a purple hue which is why it is sometimes used in fireworks.
  • Rubidium has to be kept in a vacuum sealed location due to its ability to combust in the air. This comes from the violent reaction between water and rubidium.
  • Rubidium chloride is used to treat depression in dialysis patients who suffer from depleted rubidium levels.
  • Rubidium is the second most reactive metal!
  • It is the 23rd most abundant element in the Earth’s crust.
  • On average, the human body contains about 0.36 grams of Rubidium.
  • Rubidium is one of the 26 elements that is monoisotopic.
  • By measuring the rubidium isotope 87, scientists can measure the age of rocks and meteorites.
  • The body sometimes mistakes rubidium for potassium.
  • The name is derived from the Latin word which means “deepest red”.

Rubidium in the Periodic Table

Rubidium has the atomic symbol Rb with an atomic number of 37. It is located in the s-block of the periodic table, below potassium and above cesium. Rubidium is the fourth element in the alkali metals on the periodic table. Rubidium has an electron configuration of [Kr]5s1. Additionally, the element has an electronegativity of 0.8 on the Pauling scale. 

Rubidium in Today’s World

Uses of Rubidium for Colorization

The element Rubidium is used ceramics and glassmaking to color the materials. Special lasers that take advantage of rubidium salts are used to create a purple hue in glass. It’s also used in high voltage ceramic insulators in order to get the same purple hue. This purple hue is also sought after for the production of fireworks. Since rubidium is highly reactive, it is an ideal ingredient for such a powerful display of color in the sky.

The element rubidium in fireworks.

Rubidium in The Lab

The element rubidium is used as a “getter” inside the laboratory. Since it is highly reactive, it is used in vacuum tubes to “get” any residual compounds out of the tube. Inside the body, since rubidium is very similar to the element potassium, it is often used as a replacement for potassium. This doesn’t have any particular effect on the body. However, research is currently being done into the use of rubidium chloride in the treatment of depression in dialysis patients and in relation to metabolism.

Rubidium in the Future

Even though the element rubidium doesn’t currently have many practical uses, doesn’t mean that scientists aren’t researching ways to make it so! Currently rubidium is being used as a potential replacement for cesium in ion propulsion thrusters to push vehicles through space due to the lack of air movement. It’s also used in night vision goggles and photoelectric cells. Rubidium-87 is also used in atomic clocks that keep the most accurate record of time.

Where is the Rubidium Element Found?

Rubidium is commonly found in the presence of many minerals. The most common of these is lepidolite and rubidium is extracted as a byproduct of lithium. It can also be found in brines and potassium minerals.

When and How was Rubidium Discovered?

In 1861, the German chemists, Robert Bunsen and Gustav Kirchhoff, discovered the element rubidium by sampling the mineral lepidolite using a spectroscope. Upon doing this, they noticed two deep red spectral lines, of which the element was named for as previously mentioned from the Latin name for “deep red”, rubidius. Later in 1863, Robert Bunsen, whom the Bunsen burner is named after, isolated rubidium by using flame spectroscopy.

Rubidium in Chemistry – Compounds, Reactions, Isotopes, Oxidation States

Rubidium Element Compounds and Reactions

  • Hydrates: Rb2SO4·CuSO4·6H2O
  • Oxides: Rb2O, RbO2
  • Halides: RbCl, RbF, RbI, RbBr

Elemental rubidium has a violent reaction when it exposed both to air and to water. With water it creates rubidium hydroxide and oxygen gas.

    \begin{align*} 2Rb(\text{s}) + 2H_{2}O(\text{l}) \rightarrow 2Rb(OH)(\text{s}) + O_{2}(\text{g}) \end{align*}

When exposed to oxygen it creates a tarnished surface of rubidium oxide.

    \begin{align*} Rb(\text{s}) + O_{2}(\text{g}) \rightarrow RbO_{2}(\text{s}) \end{align*}

Isolation of Elemental Rubidium

Rubidium Isotopes

Rubidium only has one stable isotope, rubidium-85. However, rubidium also has a radioactive isotope, rubidium-87, that has a half-life of 49 billion years. This beta decays to strontium-87.

Oxidation States of Rubidium Element

There is also only one common oxidation state for rubidium, +1.

Properties of Rubidium Element

  • Atomic Symbol: Rb
  • Melting point: 38.9°C
  • Boiling point: 688°C
  • Density: 1.53 g/ml
  • Atomic weight: 85.47g
  • Atomic number: 37
  • Electronegativity: 0.8
  • Molar heat capacity: J/(mol*K)
  • Classification: Alkali Metal
  • Natural abundance in the Earth’s crust: 90 ppm
  • Electron shell configuration: [Kr]5s1
  • Stable Isotopes: 85
  • Found naturally in the minerals pollucite, carnallite, leucite and lepidolite.
  • Toxicity: Generally nontoxic as it exits the body very fast through the urinary tract.

Where Can I Buy The Rubidium Element?

Pure rubidium is rare and hence, can be expensive. However, there are online vendors who supply elements such Sigma Aldrich and Lucretia.

Enjoyed reading about manganese? Check out other elements on our INTERACTIVE PERIODIC TABLE!