Radium

Radium

Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226,...

(Ra) has no stable or nearly stable isotope

Isotope

Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

s, and thus a standard atomic mass

Atomic mass

The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....

 cannot be given. The longest lived, and most common, isotope of radium is ²²⁶Ra with a half-life of 1600 years. ²²⁶Ra occurs in the disintegration chain of ²³⁸U

Uranium-238

Uranium-238 is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: it can capture a slow neutron and after two beta decays become fissile plutonium-239...

 (often referred to as the radium series.) Radium has 35 known isotopes from ²⁰¹Ra to ²³⁵Ra, with the newest being ²³⁵Ra.

Table

nuclide symbol	historic name	Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... )	N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... )	isotopic mass (u)	half-life	decay mode(s)Abbreviations: CD: Cluster decay Cluster decay Cluster decay is a type of nuclear decay in which a parent atomic nucleus with A nucleons and Z protons emits a cluster of Ne neutrons and Ze protons heavier than an alpha particle but lighter than a typical binary fission fragment Cluster decay (also named heavy particle radioactivity or heavy... EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer....	daughter isotope(s)Bold for stable isotopes	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
		excitation energy
202Ra		88	114	202.00989(7)	2.6(21) ms [0.7(+33-3) ms]			0+
203Ra		88	115	203.00927(9)	4(3) ms	α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less...	199Rn	(3/2-)
						β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...  (rare)	203Fr
203mRa		220(90) keV			41(17) ms	α	199Rn	(13/2+)
						β+ (rare)	203Fr
204Ra		88	116	204.006500(17)	60(11) ms [59(+12-9) ms]	α (99.7%)	200Rn	0+
						β+ (.3%)	204Fr
205Ra		88	117	205.00627(9)	220(40) ms [210(+60-40) ms]	α	201Rn	(3/2-)
						β+ (rare)	205Fr
205mRa		310(110)# keV			180(50) ms [170(+60-40) ms]	α	201Rn	(13/2+)
						IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer....  (rare)	205Ra
206Ra		88	118	206.003827(19)	0.24(2) s	α	202Rn	0+
207Ra		88	119	207.00380(6)	1.3(2) s	α (90%)	203Rn	(5/2-,3/2-)
						β+ (10%)	207Fr
207mRa		560(50) keV			57(8) ms	IT (85%)	207Ra	(13/2+)
						α (15%)	203Rn
						β+ (.55%)	207Fr
208Ra		88	120	208.001840(17)	1.3(2) s	α (95%)	204Rn	0+
						β+ (5%)	208Fr
208mRa		1800(200) keV			270 ns			(8+)
209Ra		88	121	209.00199(5)	4.6(2) s	α (90%)	205Rn	5/2-
						β+ (10%)	209Fr
210Ra		88	122	210.000495(16)	3.7(2) s	α (96%)	206Rn	0+
						β+ (4%)	210Fr
210mRa		1800(200) keV			2.24 µs			(8+)
211Ra		88	123	211.000898(28)	13(2) s	α (97%)	207Rn	5/2(-)
						β+ (3%)	211Fr
212Ra		88	124	211.999794(12)	13.0(2) s	α (85%)	208Rn	0+
						β+ (15%)	212Fr
212m1Ra		1958.4(5) keV			10.9(4) µs			(8)+
212m2Ra		2613.4(5) keV			0.85(13) µs			(11)-
213Ra		88	125	213.000384(22)	2.74(6) min	α (80%)	209Rn	1/2-
						β+ (20%)	213Fr
213mRa		1769(6) keV			2.1(1) ms	IT (99%)	213Ra	17/2-#
						α (1%)	209Rn
214Ra		88	126	214.000108(10)	2.46(3) s	α (99.94%)	210Rn	0+
						β+ (.06%)	214Fr
215Ra		88	127	215.002720(8)	1.55(7) ms	α	211Rn	(9/2+)#
215m1Ra		1877.8(5) keV			7.1(2) µs			(25/2+)
215m2Ra		2246.9(5) keV			1.39(7) µs			(29/2-)
215m3Ra		3756.6(6)+X keV			0.555(10) µs			(43/2-)
216Ra		88	128	216.003533(9)	182(10) ns	α	212Rn	0+
						EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...  (1×10−8%)	216Fr
217Ra		88	129	217.006320(9)	1.63(17) µs	α	213Rn	(9/2+)
218Ra		88	130	218.007140(12)	25.2(3) µs	α	214Rn	0+
						β+β+ (rare)	218Rn
219Ra		88	131	219.010085(9)	10(3) ms	α	215Rn	(7/2)+
220Ra		88	132	220.011028(10)	17.9(14) ms	α	216Rn	0+
221Ra		88	133	221.013917(5)	28(2) s	α	217Rn	5/2+
						CD Cluster decay Cluster decay is a type of nuclear decay in which a parent atomic nucleus with A nucleons and Z protons emits a cluster of Ne neutrons and Ze protons heavier than an alpha particle but lighter than a typical binary fission fragment Cluster decay (also named heavy particle radioactivity or heavy...  (1.2×10−10%)	207Pb 14C Carbon-14 Carbon-14, 14C, or radiocarbon, is a radioactive isotope of carbon with a nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues , to date archaeological, geological, and hydrogeological...
222Ra		88	134	222.015375(5)	38.0(5) s	α	218Rn	0+
						CD (3×10−8%)	208Pb 14C
223Ra	Actinium X	88	135	223.0185022(27)	11.43(5) d	α	219Rn	3/2+	TraceIntermediate decay product Decay product In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...  of 235U Uranium-235 - References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...
						CD (6.4×10−8%)	209Pb 14C
224Ra	Thorium X	88	136	224.0202118(24)	3.6319(23) d	α	220Rn	0+	TraceIntermediate decay product of 232Th
						CD (4.3×10−9%)	210Pb 14C
225Ra		88	137	225.023612(3)	14.9(2) d	β-	225Ac	1/2+
226Ra	RadiumSource of element's name	88	138	226.0254098(25)	1600(7) y	α	222Rn	0+	TraceIntermediate decay product of 238U Uranium-238 Uranium-238 is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: it can capture a slow neutron and after two beta decays become fissile plutonium-239...
						β-β- (rare)	226Th
						CD (2.6×10−9%)	212Pb 14C
227Ra		88	139	227.0291778(25)	42.2(5) min	β-	227Ac	3/2+
228Ra	Mesothorium 1	88	140	228.0310703(26)	5.75(3) y	β-	228Ac	0+	Trace
229Ra		88	141	229.034958(20)	4.0(2) min	β-	229Ac	5/2(+)
230Ra		88	142	230.037056(13)	93(2) min	β-	230Ac	0+
231Ra		88	143	231.04122(32)#	103(3) s	β-	231Ac	(5/2+)
231mRa		66.21(9) keV			~53 µs			(1/2+)
232Ra		88	144	232.04364(30)#	250(50) s	β-	232Ac	0+
233Ra		88	145	233.04806(50)#	30(5) s	β-	233Ac	1/2+#
234Ra		88	146	234.05070(53)#	30(10) s	β-	234Ac	0+

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