Rubidium
Definition and meaning of Rubidium in chemistry.
![Rubidium element card: symbol Rb, atomic number 37, atomic mass 85.468, electron configuration [Kr] 5s¹, oxidation states +1, Alkali metal, group 1, period 5, solid at room temperature.](/assets/images/terms/rubidium-chemical-element.webp)
Rubidium is an alkali metal chemical element with the symbol Rb and atomic number 37. It is a very soft, silvery-white metal that easily loses its outer electron. This property makes rubidium one of the most reactive elements on Earth.
In more detail
Rubidium sits in group 1 of the periodic table with other alkali metals. It shares extreme reactivity with heavy metals like potassium and cesium. Rubidium oxidizes rapidly and will catch fire spontaneously in normal air.
It also reacts violently when it comes into contact with liquid water. This dangerous chemical reaction forms rubidium hydroxide and flammable hydrogen gas. The intense heat from the reaction immediately ignites the hydrogen gas.
Because of this extreme reactivity, pure rubidium never occurs freely in nature. Instead, it is scattered throughout complex minerals like lepidolite, pollucite, and carnallite. Rubidium has a notably low melting point for a solid metal.
In fact, it can literally melt into a liquid on a hot day. A rubidium atom effortlessly loses its single outer valence electron. Valence electrons are the outermost electrons that form chemical bonds between atoms.
Losing this electron forms a stable Rb+ ion in its chemical compounds. Scientists must handle rubidium carefully to prevent dangerous explosions in the lab.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Rb |
| Atomic number | 37 |
| Atomic mass | 85.468 u |
| Category | Alkali-Metal |
| Melting point | 39.3 degrees Celsius |
| Discoverers | Robert Bunsen and Gustav Kirchhoff (1861) |
Companies strategically use rubidium to manufacture specific glasses for modern telecommunications. These special glasses help build efficient fiber optic networks around the world. Manufacturers also use rubidium to produce photocells for various electronic devices. A photocell is a sensor that changes electrical resistance when exposed to light. Finally, scientists use rubidium in the highly precise oscillators of some atomic clocks. These advanced clocks keep exact time for GPS satellites and global computer networks.
Frequently asked questions
How must chemists store elemental rubidium to prevent explosions?
They must carefully store pure rubidium submerged completely in dry mineral oil. Alternatively, they can seal it in a glass tube filled with an unreactive gas like argon.
Is natural rubidium considered a radioactive material?
Natural rubidium contains two isotopes, and one of them is slightly radioactive. However, this isotope has a very long half-life of nearly 49 billion years.
Related terms
Sources & references
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