Rubidium

Rubidium is a chemical element wi seembol Rb an atomic nummer 37. Rubidium is a saft, sillery-white metallic element o the alkali metal group, wi an atomic mass o 85.4678. Elemental rubidium is heichly reactive, wi properties seemilar tae those o ither alkali metals, sic as very rapid oxidation in air. Naitural rubidium is a mix o twa isotopes: ⁸⁵Rb, the anly stable ane, constitutes 72% o it. The remainin 28% is the slichtly radioactive ⁸⁷Rb wi a hauf-life o 49 billion year—mair nor three times langer than the estimatit age o the universe.

Rubidium, ₃₇Rb

Rubidium
Pronunciation	/ruːˈbɪdiəm/ ​(roo-BID-ee-əm)
Appearance	grey white
Standard atomic weight Ar, std(Rb)	7001854678000000000♠85.4678(3)[1]
Rubidium in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium K ↑ Rb ↓ Cs krypton ← rubidium → strontium
Atomic nummer (Z)	37
Group	group 1 (alkali metals)
Period	period 5
Block	s-block
Element category	Alkali metal
Electron confeeguration	[Kr] 5s1
Electrons per shell	2, 8, 18, 8, 1
Pheesical properties
Phase at STP	solit
Meltin pynt	312.45 K ​(39.30 °C, ​102.74 °F)
Bylin pynt	961 K ​(688 °C, ​1270 °F)
Density (near r.t.)	1.532 g/cm3
when liquid (at m.p.)	1.46 g/cm3
Treeple pynt	312.41 K, ​? kPa[2]
Creetical pynt	2093 K, 16 MPa (extrapolatit)[2]
Heat o fusion	2.19 kJ/mol
Heat o vapourisation	69 kJ/mol
Molar heat capacity	31.060 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 434 486 552 641 769 958
Atomic properties
Oxidation states	−1, +1 strangly basic
Electronegativity	Pauling scale: 0.82
Ionisation energies	1st: 403 kJ/mol 2nd: 2632.1 kJ/mol 3rd: 3859.4 kJ/mol
Atomic radius	empirical: 248 pm
Covalent radius	220±9 pm
Van der Waals radius	303 pm
Spectral lines o rubidium
Ither properties
Naitural occurrence	primordial
Creestal structur	​body-centred cubic (bcc)
Speed o soond thin rod	1300 m/s (at 20 °C)
Thermal expansion	90 µm/(m·K)[3] (at r.t.)
Thermal conductivity	58.2 W/(m·K)
Electrical resistivity	128 nΩ·m (at 20 °C)
Magnetic orderin	paramagnetic[4]
Young's modulus	2.4 GPa
Bulk modulus	2.5 GPa
Mohs haurdness	0.3
Brinell haurdness	0.216 MPa
CAS Nummer	7440-17-7
History
Diskivery	Robert Bunsen an Gustav Kirchhoff (1861)
First isolation	George de Hevesy
Main isotopes o rubidium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 83Rb syn 86.2 d ε 83Kr γ – 84Rb syn 32.9 d ε 84Kr β+ 84Kr γ – β− 84Sr 85Rb 72.17% stable 86Rb syn 18.65 d β− 86Sr γ – 87Rb 27.83% 4.9×1010 y β− 87Sr
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