Template:Infobox rubidium

Rubidium,  ₃₇Rb

General properties
Name, symbol	rubidium, Rb
Appearance	grey white
Pronunciation	/rᵿˈbɪdiəm/ roo-BID-ee-əm
Rubidium in the periodic table
K ↑ Rb ↓ Cs krypton ← rubidium → strontium
Atomic number (Z)	37
Group, block	group 1 (alkali metals), s-block
Period	period 5
Element category	alkali metal
Standard atomic weight (±) (Ar)	85.4678(3)
Electron configuration	[Kr] 5s1
per shell	2, 8, 18, 8, 1
Physical properties
Phase	solid
Melting point	312.45 K ​(39.30 °C, ​102.74 °F)
Boiling point	961 K ​(688 °C, ​1270 °F)
Density near r.t.	1.532 g/cm3
when liquid, at m.p.	1.46 g/cm3
Triple point	312.41 K, ​? kPa
Critical point	2093 K, 16 MPa (extrapolated)
Heat of fusion	2.19 kJ/mol
Heat of vaporization	69 kJ/mol
Molar heat capacity	31.060 J/(mol·K)
vapor pressure 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 ​(a strongly basic oxide)
Electronegativity	Pauling scale: 0.82
Ionization 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
Miscellanea
Crystal structure	​body-centered cubic (bcc)
Speed of sound thin rod	1300 m/s (at 20 °C)
Thermal expansion	90 µm/(m·K) (at r.t.)
Thermal conductivity	58.2 W/(m·K)
Electrical resistivity	128 nΩ·m (at 20 °C)
Magnetic ordering	paramagnetic
Young's modulus	2.4 GPa
Bulk modulus	2.5 GPa
Mohs hardness	0.3
Brinell hardness	0.216 MPa
CAS Number	7440-17-7
History
Discovery	Robert Bunsen and Gustav Kirchhoff (1861)
First isolation	George de Hevesy
Most stable isotopes of rubidium
iso NA half-life DM DE (MeV) DP 83Rb syn 86.2 d ε – 83Kr γ 0.52, 0.53, 0.55 – 84Rb syn 32.9 d ε – 84Kr β+ 1.66, 0.78 84Kr γ 0.881 – β− 0.892 84Sr 85Rb 72.17% 85Rb is stable with 48 neutrons 86Rb syn 18.65 d β− 1.775 86Sr γ 1.0767 – 87Rb 27.83% 4.9×1010 y β− 0.283 87Sr

References

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