Radium (Ra)

Radioactive metallic transuranic element, belongs to group 2 of the periodic table. Most stable isotope, Ra-226 has a half-life of 1602 years, which decays into radon. Isolated from pitchblende in 1898 Marie and Pierre Curie.

Atomic Number	88
Atomic Weight	226
Mass Number	201

Group	2
Period	7
Block	s

Protons	88 p⁺
Neutrons	113 n⁰
Electrons	88 e^-

Properties

Energy
Atomic Radius	215 pm 292 pm
Molar Volume	45 cm³/mol
Covalent Radius	201 pm 173 pm 159 pm 221 pm
Metallic Radius
Ionic Radius	148 pm 170 pm
Crystal Radius	162 pm 184 pm
Van der Waals Radius	283 pm 327 pm 283 pm 367.7 pm
Density	5 g/cm³
Proton Affinity
Electron Affinity	0.1 eV/particle
Ionization Energy	5.278424 eV/particle 10.147153 eV/particle 31 eV/particle 41 eV/particle 52.9 eV/particle 64 eV/particle 82 eV/particle 97 eV/particle 100 eV/particle 140 eV/particle 204.9 eV/particle 227 eV/particle 250 eV/particle 274 eV/particle 299 eV/particle 324 eV/particle 356 eV/particle 382 eV/particle 409 eV/particle 435 eV/particle 570 eV/particle 600 eV/particle 630 eV/particle 660 eV/particle 740 eV/particle 770 eV/particle 860 eV/particle 900 eV/particle 970 eV/particle 1,040 eV/particle 1,110 eV/particle 1,180 eV/particle 1,250 eV/particle 1,320 eV/particle 1,390 eV/particle 1,460 eV/particle 1,530 eV/particle 1,610 eV/particle 1,680 eV/particle 1,750 eV/particle 1,820 eV/particle 1,880 eV/particle 2,208 eV/particle 2,271 eV/particle 2,338 eV/particle 2,409 eV/particle 2,477 eV/particle 2,544 eV/particle 2,662 eV/particle 2,731 eV/particle 2,806 eV/particle 2,876 eV/particle 3,155 eV/particle 3,224 eV/particle 3,300 eV/particle 3,368 eV/particle 3,682 eV/particle 3,762 eV/particle 3,959 eV/particle 4,040 eV/particle 6,565 eV/particle 6,718 eV/particle 6,881 eV/particle 7,056 eV/particle 7,222 eV/particle 7,380 eV/particle 7,720 eV/particle 7,890 eV/particle 8,080 eV/particle 8,250 eV/particle 8,730 eV/particle 8,880 eV/particle 9,040 eV/particle 9,200 eV/particle 10,190 eV/particle 10,360 eV/particle 10,720 eV/particle 10,890 eV/particle 22,900 eV/particle 23,300 eV/particle 23,750 eV/particle 24,160 eV/particle 27,830 eV/particle 28,370 eV/particle 29,050 eV/particle 29,479.8 eV/particle 116,848.7 eV/particle 118,931.3 eV/particle

Heat of Vaporization	113 kJ/mol
Heat of Fusion	9.6 kJ/mol
Heat of Formation	159 kJ/mol
Electrons
Electron Shells	2, 8, 18, 32, 18, 8, 2

Valence Electrons	2

Electron Configuration	[Rn] 7s²

Oxidation States	2
Electronegativity	0.09789 0.9
Electrophilicity	0.6982685447294388 eV/particle
Phases
Phase	Solid
Gas Phase
Boiling Point
Melting Point	969.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color	Silver #ffffff #007d00 #007d00
Appearance	silvery white metallic
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type	Conductor
Electrical Conductivity	1 MS/m
Electrical Resistivity	0.000001 m Ω
Superconducting Point
Magnetism
Type
Magnetic Susceptibility (Mass)
Magnetic Susceptibility (Molar)
Magnetic Susceptibility (Volume)
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal Structure	Body Centered Cubic ()
Lattice Constant
Lattice Angles	π/2, π/2, π/2
Mechanical Properties
Hardness
Bulk Modulus
Shear Modulus
Young Modulus
Poisson Ratio
Speed of Sound
Classification
Category	Alkaline earth metals, Alkaline earth metals
CAS Group	IIA
IUPAC Group	IIA
Glawe Number	13
Mendeleev Number	10
Pettifor Number	13
Geochemical Class	U/Th decay series
Goldschmidt Class	litophile
Other
Gas Basicity
Dipole Polarizability	246 ± 4 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section	13
Neutron Mass Absorption
Quantum Numbers	1S0
Space Group	229 (Im_3m)

Isotopes of Radium

Stable Isotopes	0
Unstable Isotopes	35
Radioactive Isotopes	35

²⁰¹Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	201.012814699 ± 0.000021794 Da
Mass Number	201
G-Factor
Half Life	20 ± 30 ms
Spin	3/2
Quadrupole Moment
Discovery Year	2005
Parity	-

²⁰¹Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²⁰²Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	202.009742305 ± 0.000016122 Da
Mass Number	202
G-Factor	0
Half Life	4.1 ± 1.1 ms
Spin	0
Quadrupole Moment	0
Discovery Year	2005
Parity	+

²⁰²Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²⁰³Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	203.009233907 ± 0.0000104 Da
Mass Number	203
G-Factor
Half Life	36 ± 13 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1996
Parity	-

²⁰³Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²⁰⁴Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	204.006506855 ± 0.00000958 Da
Mass Number	204
G-Factor	0
Half Life	60 ± 9 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1995
Parity	+

²⁰⁴Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²⁰⁵Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	205.006230692 ± 0.000024446 Da
Mass Number	205
G-Factor
Half Life	220 ± 50 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1987
Parity	-

²⁰⁵Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²⁰⁶Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	206.003827842 ± 0.000019332 Da
Mass Number	206
G-Factor	0
Half Life	240 ± 20 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1967
Parity	+

²⁰⁶Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²⁰⁷Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	207.00377242 ± 0.000062572 Da
Mass Number	207
G-Factor
Half Life	1.38 ± 0.18 s
Spin	5/2
Quadrupole Moment
Discovery Year	1967
Parity	-

²⁰⁷Ra Decay Modes

Decay Mode	Intensity
α (α emission)	86%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²⁰⁸Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	208.001855012 ± 0.000009686 Da
Mass Number	208
G-Factor	0
Half Life	1.11 ± 0.045 s
Spin	0
Quadrupole Moment	0
Discovery Year	1967
Parity	+

²⁰⁸Ra Decay Modes

Decay Mode	Intensity
α (α emission)	87%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²⁰⁹Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	209.001994902 ± 0.000006169 Da
Mass Number	209
G-Factor	0.3444 ± 0.0052
Half Life	4.71 ± 0.08 s
Spin	5/2
Quadrupole Moment	0.39 ± 0.04
Discovery Year	1967
Parity	-

²⁰⁹Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²¹⁰Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	210.000475406 ± 0.000009868 Da
Mass Number	210
G-Factor	0
Half Life	4 ± 0.1 s
Spin	0
Quadrupole Moment	0
Discovery Year	1967
Parity	+

²¹⁰Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²¹¹Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	211.000893049 ± 0.000005331 Da
Mass Number	211
G-Factor	0.3496 ± 0.0016
Half Life	12.6 ± 1.2 s
Spin	5/2
Quadrupole Moment	0.46 ± 0.04
Discovery Year	1967
Parity	-

²¹¹Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²¹²Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	211.999786619 ± 0.000011007 Da
Mass Number	212
G-Factor	0
Half Life	13 ± 0.2 s
Spin	0
Quadrupole Moment	0
Discovery Year	1967
Parity	+

²¹²Ra Decay Modes

Decay Mode	Intensity
α (α emission)	%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

²¹³Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	213.000370971 ± 0.00001054 Da
Mass Number	213
G-Factor	1.22 ± 0.004
Half Life	2.73 ± 0.05 m
Spin	1/2
Quadrupole Moment	0
Discovery Year	1955
Parity	-

²¹³Ra Decay Modes

Decay Mode	Intensity
α (α emission)	87%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	13%

²¹⁴Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	214.00009956 ± 0.000005636 Da
Mass Number	214
G-Factor	0
Half Life	2.437 ± 0.016 s
Spin	0
Quadrupole Moment	0
Discovery Year	1967
Parity	+

²¹⁴Ra Decay Modes

Decay Mode	Intensity
α (α emission)	99.941%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	0.059%

²¹⁵Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	215.002718208 ± 0.00000773 Da
Mass Number	215
G-Factor
Half Life	1.669 ± 0.009 ms
Spin	9/2
Quadrupole Moment
Discovery Year	1967
Parity	+

²¹⁵Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²¹⁶Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	216.003533534 ± 0.000008592 Da
Mass Number	216
G-Factor	0
Half Life	172 ± 7 ns
Spin	0
Quadrupole Moment	0
Discovery Year	1972
Parity	+

²¹⁶Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
ϵ (electron capture)	1%

²¹⁷Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	217.006322676 ± 0.000007564 Da
Mass Number	217
G-Factor
Half Life	1.95 ± 0.12 us
Spin	9/2
Quadrupole Moment
Discovery Year	1970
Parity	+

²¹⁷Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²¹⁸Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	218.007134297 ± 0.000010528 Da
Mass Number	218
G-Factor	0
Half Life	25.91 ± 0.14 us
Spin	0
Quadrupole Moment	0
Discovery Year	1970
Parity	+

²¹⁸Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²¹⁹Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	219.010084715 ± 0.000007315 Da
Mass Number	219
G-Factor
Half Life	9 ± 2 ms
Spin	7/2
Quadrupole Moment
Discovery Year	1952
Parity

²¹⁹Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²²⁰Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	220.011027542 ± 0.000008153 Da
Mass Number	220
G-Factor	0
Half Life	18.1 ± 1.2 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1949
Parity	+

²²⁰Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²²¹Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	221.013917293 ± 0.00000497 Da
Mass Number	221
G-Factor	-0.0716 ± 0.00068
Half Life	25 ± 4 s
Spin	5/2
Quadrupole Moment	1.92 ± 0.06
Discovery Year	1949
Parity	+

²²¹Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
14C	1.2%

²²²Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	222.015373371 ± 0.000004781 Da
Mass Number	222
G-Factor	0
Half Life	33.6 ± 0.4 s
Spin	0
Quadrupole Moment	0
Discovery Year	1948
Parity	+

²²²Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
14C	3%

²²³Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	223.018500648 ± 0.000002243 Da
Mass Number	223
G-Factor	0.17946666666667 ± 0.00053333333333333
Half Life	11.4352 ± 0.001 d
Spin	3/2
Quadrupole Moment	1.22 ± 0.03
Discovery Year	1905
Parity	+

²²³Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
14C	8.9%

²²⁴Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	224.020210361 ± 0.000001944 Da
Mass Number	224
G-Factor	0
Half Life	3.6316 ± 0.0014 d
Spin	0
Quadrupole Moment	0
Discovery Year	1902
Parity	+

²²⁴Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
14C	4%

²²⁵Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	225.023610502 ± 0.000002786 Da
Mass Number	225
G-Factor	-1.46 ± 0.004
Half Life	14.82 ± 0.19 d
Spin	1/2
Quadrupole Moment	0
Discovery Year	1947
Parity	+

²²⁵Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²²⁶Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	226.025408186 ± 0.000002068 Da
Mass Number	226
G-Factor	0
Half Life	1.6 ± 0.007 ky
Spin	0
Quadrupole Moment	0
Discovery Year	1898
Parity	+

²²⁶Ra Decay Modes

Decay Mode	Intensity
α (α emission)	100%
14C	2.6%
2β⁻ (double β⁻ decay)	%

²²⁷Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	227.029176205 ± 0.000002089 Da
Mass Number	227
G-Factor	-0.26733333333333 ± 0.00073333333333333
Half Life	42.2 ± 0.5 m
Spin	3/2
Quadrupole Moment	1.53 ± 0.06
Discovery Year	1953
Parity	+

²²⁷Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²²⁸Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	228.031068574 ± 0.000002141 Da
Mass Number	228
G-Factor	0
Half Life	5.75 ± 0.03 y
Spin	0
Quadrupole Moment	0
Discovery Year	1907
Parity	+

²²⁸Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²²⁹Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	229.034956703 ± 0.000016576 Da
Mass Number	229
G-Factor	0.19968 ± 0.00056
Half Life	4 ± 0.2 m
Spin	5/2
Quadrupole Moment	2.99 ± 0.12
Discovery Year	1975
Parity	+

²²⁹Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²³⁰Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	230.037054776 ± 0.000011053 Da
Mass Number	230
G-Factor	0
Half Life	93 ± 2 m
Spin	0
Quadrupole Moment	0
Discovery Year	1978
Parity	+

²³⁰Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²³¹Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	231.041027085 ± 0.000012206 Da
Mass Number	231
G-Factor	-0.14216 ± 0.00044
Half Life	104 ± 1 s
Spin	5/2
Quadrupole Moment
Discovery Year	1983
Parity	+

²³¹Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²³²Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	232.043475267 ± 0.000009823 Da
Mass Number	232
G-Factor	0
Half Life	4 ± 0.3 m
Spin	0
Quadrupole Moment	0
Discovery Year	1983
Parity	+

²³²Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²³³Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	233.04759457 ± 0.000009235 Da
Mass Number	233
G-Factor
Half Life	30 ± 5 s
Spin	1/2
Quadrupole Moment	0
Discovery Year	1990
Parity	+

²³³Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²³⁴Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	234.0503821 ± 0.000009 Da
Mass Number	234
G-Factor	0
Half Life	30 ± 10 s
Spin	0
Quadrupole Moment	0
Discovery Year	1990
Parity	+

²³⁴Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ SF (β⁻-delayed fission)	%

²³⁵Ra

Abundance	Radioactive ☢️
Relative Atomic Mass	235.05489 ± 0.000322 Da
Mass Number	235
G-Factor
Half Life
Spin	5/2
Quadrupole Moment
Discovery Year
Parity	+

²³⁵Ra Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%

History

Radium was discovered by Marie Curie and Pierre Curie in 1898. They extracted the radium compound from a uraninite sample. Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne in 1910 through the electrolysis of radium chloride by using a mercury cathode and distilling in an atmosphere of hydrogen gas. From the Latin word radius meaning ray

Discoverers	Pierre and Marie Curie
Discovery Location	France
Discovery Year	1898
Etymology (Name Origin)	Latin: radius (ray).
Pronunciation	RAY-di-em (English)

Radium is highly radioactive and carcinogenic

Radium imparts a carmine red color to a flame

Uses

Radium was formerly used in self-luminous paints for watches, nuclear panels, aircraft switches, clocks, and instrument dials. Radium chloride was used in medicine to produce radon gas which in turn was used as a cancer treatment. The isotope ²²³Ra is currently under investigation for use in medicine as a cancer treatment of bone metastasis. Used in treating cancer because of the gamma rays it gives off.

Sources

Found in uranium ores at 1 part per 3 million parts uranium.

Abundance
Abundance in Earth's crust	0.0000009 mg/kg
Abundance in Oceans	0.000000000089 mg/L
Abundance in Human Body	0.0000000000001 %
Abundance in Meteor
Abundance in Sun
Abundance in Universe	0 %

Nuclear Screening Constants

Radium on ChemicalAid

AEDA subject keyword ID	17547
Australian Educational Vocabulary ID	scot/3564
BNCF Thesaurus ID	18888
Biblioteca Nacional de España ID	XX526711
Bibliothèque nationale de France ID	11979118t
Brockhaus Enzyklopädie online ID	radium
CAB ID	18810
CAS Registry Number	7440-14-4
ChEBI ID	33325
ChemSpider ID	4886483
DSSTOX compound identifier	DTXCID70875702
DSSTox substance ID	DTXSID2024294
Den Store Danske ID	radium
ECHA Substance Infocard ID	100.028.293
Encyclopædia Britannica Online ID	science/radium
Encyclopædia Universalis ID	radium
Freebase ID	/m/025scm7
French Vikidia ID	Radium
GND ID	4176842-5
Great Russian Encyclopedia Online ID	3489135
InChI	InChI=1S/Ra
InChIKey	HCWPIIXVSYCSAN-UHFFFAOYSA-N
KBpedia ID	Radium
Library of Congress authority ID	sh85110804
MeSH descriptor ID	D011883
NE.se ID	radium
NKCR AUT ID	ph150526
Namuwiki ID	라듐
National Diet Library ID	00569336
National Library of Israel J9U ID	987007560614605171
OmegaWiki Defined Meaning	347064
Online PWN Encyclopedia ID	3965238
OpenAlex ID	C550196577
PSH ID	5755
PubChem CID	6328144
Quora topic ID	Radium
RxNorm ID	1546450
Spanish Vikidia ID	Radio_(elemento_químico)
Store medisinske leksikon ID	radium
Store norske leksikon ID	radium
The Encyclopedia of Science Fiction ID	radium
Treccani ID	radio_res-fda11266-e1eb-11df-9962-d5ce3506d72e
UK Archival Thesaurus ID	f2/mt225/4347/5017
UNESCO Thesaurus ID	concept14022
UNII	W90AYD6R3Q
WordNet 3.1 Synset ID	14676100-n
YSO ID	19781

Radium (Ra)

Properties

Isotopes of Radium

201Ra

201Ra Decay Modes

202Ra

202Ra Decay Modes

203Ra

203Ra Decay Modes

204Ra

204Ra Decay Modes

205Ra

205Ra Decay Modes

206Ra

206Ra Decay Modes

207Ra

207Ra Decay Modes

208Ra

208Ra Decay Modes

209Ra

209Ra Decay Modes

210Ra

210Ra Decay Modes

211Ra

211Ra Decay Modes

212Ra

212Ra Decay Modes

213Ra

213Ra Decay Modes

214Ra

214Ra Decay Modes

215Ra

215Ra Decay Modes

216Ra

216Ra Decay Modes

217Ra

217Ra Decay Modes

218Ra

218Ra Decay Modes

219Ra

219Ra Decay Modes

220Ra

220Ra Decay Modes

221Ra

221Ra Decay Modes

222Ra

222Ra Decay Modes

223Ra

223Ra Decay Modes

224Ra

224Ra Decay Modes

225Ra

225Ra Decay Modes

226Ra

226Ra Decay Modes

227Ra

227Ra Decay Modes

228Ra

228Ra Decay Modes

229Ra

229Ra Decay Modes

230Ra

230Ra Decay Modes

231Ra

231Ra Decay Modes

232Ra

232Ra Decay Modes

233Ra

233Ra Decay Modes

234Ra

234Ra Decay Modes

235Ra

235Ra Decay Modes