Rubidium is a silvery-white, extremely soft metal that is one of the periodic table's most reactive elements. According to Chemicool, rubidium has a density around one and a half times that of water and is solid at room temperature, however it will melt if it gets a little warmer. It is found in minerals such as rubidite and rutile.
Rubidium has several allotropes, or forms, of carbon. The most common form is black anthracite, which can be obtained by heating rubidium carbonate under pressure. Less commonly, rubidium may take on a wispy white color when it is exposed to air for many years at low temperatures. This is called "alumina" and is used as a flux in aluminum smelting.
Alumina is also the name of the chemical compound made from this allotrope. Rubidium aluminate is hard but brittle and cannot be worked like other metals. However, it can be burned with a bright, stable flame and the ash can then be dissolved in hydrofluoric acid to obtain pure rubidium metal.
Other compounds of rubidium include rubidium chloride, RbCl; rubidium fluoride, RbF; and rubidium oxide, RbO.
Rubidium has two naturally occurring isotopes: 95% rubidium (85% uranium) and 5% strontium.
It can be found in trace amounts in soil, rock, and water. The only significant source of rubidium is radioactive radium which decays into it.
Radon is a gaseous element that occurs naturally in rocks. It becomes toxic when it enters your body through your lungs. The main way to prevent this is by not smoking or using smokeless tobacco. Radon gas is also released from rocks when they decay at high levels of radiation. This is especially true for uranium rocks such as schist, gneiss, and granite. When this happens, you should have your house inspected by a qualified professional who can tell you how much risk you are being exposed to. You may want to consider moving if you are unable to live in a radon-prone area.
Radioactive materials like radon gas and radium salts are called "alpha emitters". They produce alpha particles which have a negative charge and so are repelled by other atoms, making them move away from their original location. As these particles travel through matter, they can collide with other atoms causing more damage.
Physical characteristics Rubidium is a silvery-soft metal. It has a melting temperature of 39 degrees Celsius (102 degrees Fahrenheit) and a boiling point of 688 degrees Celsius (1,270 degF). It has a density of 1.532 g/cubic centimeter. The atomic weight of rubidium is 45.5%. Its electric resistance is about 2.2 times greater than that of sodium.
Rb has three allotropes: red Rb, white Rb2CO3, and black RB4. Red Rb can be converted to white Rb2CO3 by heating it in air. White Rb2CO3 can be converted back to red Rb by heating it in vacuum or in hydrogen gas.
Rubidium does not react with water even at high temperatures, which makes it useful for measuring extremely low levels of oxygen in fluids such as blood. It also does not oxidize in the presence of air.
Radioactive Rubidium-85 is used as a marker when tracing substances that cross the blood-brain barrier. This isotope decays into Rhodium-87, which is a component of heart tissue. So by looking for Rb in the body, doctors can see where the barrier has been crossed.
Nonradioactive Rubidium can be used as a dopant in glasses to make lasers more efficient.
Rubidium is a silvery-soft metal. Rubidium can be used in clocks, cameras, cell phones, and other devices.
It is number 71 on the list of elements. (Wikipedia)
Rubidium has been used as an atomic clock standard because of its relatively large spectral line, which allows for high resolution measurements over long periods of time. An atom's electron shell can be thought of as having three different levels that can each hold only two electrons. By pumping energy into rubidium using light of specific frequencies, those electrons can be made to jump from one level to another, which changes the frequency of the radiation given off by the atom. This ability to use oscillations at specific frequencies as a measure of energy is what makes atoms such good clocks.
The first atomic clock was built by American scientists who used uranium atoms as the oscillator. The first atomic clock based on rubidium came later from the same group. It was also called a "rubidium clock" because it used rubidium cells to pump energy into the atoms to make them oscillate. Today's commercial atomic clocks use different methods all based on the idea of using electromagnetic radiation to drive atoms into oscillation.