Radium, 88Ra
Radium electroplated on a very small sample of copper foil and covered with polyurethane to prevent reaction with the air
Radium
Pronunciation/ˈrdiəm/ (RAY-dee-əm)
Appearancesilvery white metallic
Mass number[226]
Radium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
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Ba

Ra

(Ubn)
franciumradiumactinium
Atomic number (Z)88
Groupgroup 2 (alkaline earth metals)
Periodperiod 7
Block  s-block
Electron configuration[Rn] 7s2
Electrons per shell2, 8, 18, 32, 18, 8, 2
Physical properties
Phase at STPsolid
Melting point973 K ​(700 °C, ​1292 °F) (disputed)
Boiling point2010 K ​(1737 °C, ​3159 °F)
Density (near r.t.)5.5 g/cm3
Heat of fusion8.5 kJ/mol
Heat of vaporization113 kJ/mol
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 819 906 1037 1209 1446 1799
Atomic properties
Oxidation statescommon: +2
ElectronegativityPauling scale: 0.9
Ionization energies
  • 1st: 509.3 kJ/mol
  • 2nd: 979.0 kJ/mol
Covalent radius221±2 pm
Van der Waals radius283 pm
Color lines in a spectral range
Spectral lines of radium
Other properties
Natural occurrencefrom decay
Crystal structurebody-centered cubic (bcc) (cF4)
Lattice constant
Body-centered cubic crystal structure for radium
a = 514.8 pm (near r.t.)[1]
Thermal conductivity18.6 W/(m⋅K)
Electrical resistivity1 µΩ⋅m (at 20 °C)
Magnetic orderingnonmagnetic
CAS Number7440-14-4
History
DiscoveryPierre and Marie Curie (1898)
First isolationMarie Curie (1910)
Isotopes of radium
Main isotopes[2] Decay
abun­dance half-life (t1/2) mode pro­duct
223Ra trace 11.43 d α 219Rn
224Ra trace 3.6319 d α 220Rn
225Ra trace 14.9 d β 225Ac
α[3] 221Rn
226Ra trace 1599 y α 222Rn
228Ra trace 5.75 y β 228Ac
 Category: Radium
| references
Ra · Radium
Fr ←

ibox Fr

iso
88
Ra  [e]
IB-Ra [e]
IBisos [e]
→ Ac

ibox Ac

indexes by PT (page)
child table, as reused in {IB-Ra}
Main isotopes of radium
Main isotopes[2] Decay
abun­dance half-life (t1/2) mode pro­duct
223Ra trace 11.43 d α 219Rn
224Ra trace 3.6319 d α 220Rn
225Ra trace 14.9 d β 225Ac
α[3] 221Rn
226Ra trace 1599 y α 222Rn
228Ra trace 5.75 y β 228Ac
Data sets read by {{Infobox element}}
Name and identifiers
Symbol etymology (11 non-trivial)
Top image (caption, alt)
Pronunciation
Allotropes (overview)
Group (overview)
Period (overview)
Block (overview)
Natural occurrence
Phase at STP
Oxidation states
Spectral lines image
Electron configuration (cmt, ref)
Isotopes
Standard atomic weight
  most stable isotope
Wikidata
Wikidata *
* Not used in {{Infobox element}} (2023-01-01)
See also {{Index of data sets}} · Cat:data sets (46) · (this table: )

References

  1. ^ Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  2. ^ a b Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  3. ^ a b Liang, C. F.; Paris, P.; Sheline, R. K. (2000-09-19). "α decay of 225Ra". Physical Review C. 62 (4). American Physical Society (APS): 047303. Bibcode:2000PhRvC..62d7303L. doi:10.1103/physrevc.62.047303. ISSN 0556-2813.