Rubidium

Rubidium is a chemical element with the symbol Rb and atomic number 37. It is part of the alkali metal group, like potassium and caesium. Rubidium is a soft, whitish-grey solid. It is special because it is the first alkali metal that is heavier than water.

German chemists Robert Bunsen and Gustav Kirchhoff found rubidium in 1861. They used a method called flame spectroscopy. The name rubidium comes from the Latin word rubidus, meaning deep red. This is because of the color it shows when looked at with special light.

Rubidium has many uses in science and electronics. Because it turns into a gas easily and works well with light, it is often used in experiments with laser beams. Even though rubidium is not something living things need, its particles act like potassium particles in animal cells.

Characteristics

Rubidium is a very soft, silvery-white metal. It melts at a low temperature of 39.3 °C (102.7 °F) and boils at 688 °C (1,270 °F). It can mix with mercury to form special mixtures and also combines with several other metals.

Rubidium reacts very strongly with water, creating rubidium hydroxide and hydrogen gas. This reaction can be very intense. Rubidium can also catch fire when exposed to air on its own.

Rubidium chloride is one of the most used rubidium compounds. It helps scientists study how living cells take in DNA. Other common compounds include rubidium hydroxide, rubidium carbonate used in special glass, and rubidium silver iodide, which is great for use in thin film batteries.

Rubidium has two main types, called isotopes: stable ⁸⁵Rb and radioactive ⁸⁷Rb. The radioactive type has been used to find the age of rocks. There are also other rubidium isotopes made in labs, but they break down quickly.

Occurrence

Rubidium is not very common. It makes up about 0.05% of the Earth's crust and is the 23rd most common element there. You can find it in minerals like leucite, pollucite, carnallite, and zinnwaldite. Another mineral, lepidolite, contains rubidium and is often used to get the element.

Seawater has a small amount of rubidium. This is less than the amount of potassium in seawater.

Because of its size, rubidium stays in liquid magma as it cools. This means it can be found in special types of rock called zone pegmatite ore bodies.

Two important places to find rubidium are at Bernic Lake in Manitoba, Canada, and on the Italian island of Elba. Both of these places also contain other useful elements.

Production

Rubidium is found in Earth's crust, but we don't use it much. Only a tiny amount — about 2 to 4 tonnes each year — is made. There are a few ways to separate rubidium from other elements like potassium and caesium. One way is called fractional crystallization, which has many steps to get pure rubidium. Other methods include the chlorostannate process and the ferrocyanide process.

In the 1950s and 1960s, a by-product from making potassium called Alkarb was a main source of rubidium. Today, rubidium is often made when companies produce caesium from a mineral called pollucite.

History

Rubidium was discovered in 1861 by Robert Bunsen and Gustav Kirchhoff in Heidelberg, Germany. They found it in a mineral called lepidolite using a special tool called a spectroscope. They named it rubidium after the bright red color they saw, from the Latin word rubidus, meaning "deep red".

Bunsen and Kirchhoff worked hard to separate rubidium from other materials. They made a tiny amount of rubidium metal, which was very reactive. Today, rubidium is important for research in chemistry and electronics. In 1995, a special form of rubidium helped scientists create something called a Bose-Einstein condensate.

Applications

Rubidium has been studied for use in special generators that use magnetic fields to make electricity. It is also used in science tools to cool atoms and watch how they act. This works because rubidium can be turned into a gas easily and works well with lasers.

Rubidium is important in very exact clocks and timing tools used in communication devices. It can also be used in some kinds of glass, in studying how living things work, and in medical pictures to help find and see brain tumors. Rubidium has also been looked at for possible help in treating some mood conditions.

Precautions and biological effects

Rubidium can react very strongly with water and may cause fires. It is usually stored safely under dry mineral oil or sealed in glass containers. Even a little bit of air can cause rubidium to form peroxides, so it needs careful storage, much like potassium.

When dissolved in water, rubidium behaves similarly to potassium and is found mostly inside our cells. It is not very harmful; the human body naturally contains a small amount of rubidium. Even increasing this amount significantly did not cause problems in tests. The body gets rid of rubidium over about a month. However, if too much rubidium replaces potassium in muscles, it can be dangerous.