2 Symbol: Rb Atomic number: 37 Atomic mass: 85 Symbol: Rb Atomic number: 37 Atomic mass: Group: Alkali Metal Rubidium is a chemical element in the periodic table that has the symbol Rb and atomic number 37. Rb is a soft, silvery-white metallic element of the alkali metal groupElectronic dataShells: 2,8,18,8,1 Orbitals: [Kr] 5s1 Electronegativity: 0.9, Ionization potential: eV 2. Ionization potential: eV 3. Ionization potential: 40.0 eV Oxidation states: 1 Electrical conductivity: ^6Steric DataAtomic radius: 2.98 Å Ionic radius: 1.61 Å () Covalent radius: 2.16 Å Atomic volume: 55.9 cm³/mol Density (293 K): 1.53 g/cm³ Crystal structure: Cubic: Body centeredThermal dataMelting point: °C Boiling point: 686 °C Specific heat: J/gK Heat of fusion: kJ/mol Heat of vaporization: kJ/mol Thermal conductivity: W/cmK
3 HistoryRubidium was discovered by the German chemists Robert Bunsen and Gustav Kirchoff in 1861 while analyzing samples of the mineral lepidolite (KLi2Al(Al, Si)3O10(F, OH)2) with a device called a spectroscope. The sample produced a set of deep red spectral lines they had never seen beforeThe name rubidium (from the Latin "rubidus" - dark red) was coined for its bright red spectroscopic lines.BunsenKirchoff
4 OccurrenceThis element is considered to be the 16th most abundant element in the earth's crust.It occurs naturally in the minerals leucite, pollucite, and zinnwaldite, which contains traces of up to 1% of its oxide. Lepidolite contains 1.5% rubidium and this is the commercial source of the element.Some potassium minerals and potassium chlorides also contain the element in commercially significant amounts. One notable source is also in the extensive deposits of pollucite at Bernic Lake, Manitoba. Rubidium metal can be produced by reducing rubidium chloride with calcium among other methods.
5 IsolationRubidium would not normally be made in the laboratory as it is available commercially. All syntheses require an electrolytic step as it is so difficult to add an electron to the poorly electronegative rubidium ion Rb+.Rubidium is not made by the same method as sodium as might have been expected. This is because the rubidium metal, once formed by electrolysis of liquid rubidium chloride (RbCl), is too soluble in the molten salt.cathode: Rb+(l) + e- Rb (l) anode: Cl-(l) 1/2Cl2 (g) + e-Instead, it is made by the reaction of metallic sodium with hot molten rubidium chloride.Na + RbCl Rb + NaClThis is an equilibrium reaction and under these conditions the rubidium is highly volatile and removed from the system in a form relatively free from sodium impurities, allowing the reaction to proceed.
6 Chemical reactions of the elements Reaction of rubidium with airIf rubidium is burned in air, the result is mainly formation of dark brown rubidium superoxide, RbO2.Rb(s) + O2(g) RbO2(s)Reaction of rubidium with waterRubidium metal reacts very rapidly with water to form a colourless solution of rubidium hydroxide (RbOH) and hydrogen gas (H2). The reaction is very exothermic.2 Rb(s) + 2H2O RbOH(aq) + H2(g)
7 Chemical reactions of the elements Reaction of rubidium with the halogensRubidium metal reacts vigorously with all the halogens to form rubidium halides.2Rb(s) + F2(g) RbF(s)2Rb(s) + Cl2(g) RbCl(s)2Rb(s) + Br2(g) RbBr(s)2Rb(s) + I2(g) RbI(s)Reaction of rubidium with acidsRubidium metal dissolves readily in dilute sulphuric acid to form solutions containing the aquated Rb(I) ion together with hydrogen gas, H2.2Rb(s) + H2SO4(aq) Rb+(aq) + SO42-(aq) + H2(g)
9 ApplicationsRubidium is easily ionized, and so has possible use in "ion engines" for space vehiclesAs a getter in vacuum tubes.As a photocell component.In the making of special glasses.Rubidium compounds are sometimes used in fireworks to give them a purple color.