Rubidium

Rubidium,  ₃₇Rb

General properties
Name, seembol	rubidium, Rb
Appearance	grey white
Pronunciation	/rᵿˈbɪdiəm/ roo-BID-ee-əm
Rubidium in the periodic cairt
K ↑ Rb ↓ Cs krypton ← rubidium → strontium
Atomic nummer (Z)	37
Group, block	group 1 (alkali metals), s-block
Period	period 5
Element category	alkali metal
Staundart atomic wicht (±) (Ar)	85.4678(3)
Electron configuration	[Kr] 5s1
per shell	2, 8, 18, 8, 1
Pheesical properties
Phase	solid
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
Threeple pynt	312.41 K, ​? kPa
Creetical pynt	2093 K, 16 MPa (extrapolatit)
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 ​(a strangly basic oxide)
Electronegativity	Pauling scale: 0.82
Ionisation energies	1st: 403 kJ/mol 2nt: 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
Creestal structur	​body-centred cubic (bcc)
Speed o soond 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 orderin	paramagnetic
Young's modulus	2.4 GPa
Bouk 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
Maist stable isotopes o rubidium
iso NA hauf-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 wi 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

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 years—mair nor three times langer than the estimatit age o the universe.