Radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather t ...

(₈₈Ra) has no stable or nearly stable

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

s, and thus a

standard atomic weight The standard atomic weight of a chemical element (symbol ''A''r°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, is ...

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

decay chain In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". Most radioisotopes do not decay direct ...

of ²³⁸U (often referred to as the radium series). Radium has 33 known isotopes from ²⁰²Ra to ²³⁴Ra. In 2013 it was discovered that the nucleus of radium-224 is pear-shaped. This was the first discovery of an asymmetric nucleus.

List of isotopes

, - , ²⁰²Ra , , style="text-align:right" , 88 , style="text-align:right" , 114 , 202.00989(7) , 2.6(21) ms
.7(+33−3) ms, , , 0+ , , - , rowspan=2, ²⁰³Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 115 , rowspan=2, 203.00927(9) , rowspan=2, 4(3) ms , α , ¹⁹⁹Rn , rowspan=2, (3/2−) , rowspan=2, , - , β⁺ (rare) , ²⁰³Fr , - , rowspan=2 style="text-indent:1em" , ^203mRa , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 220(90) keV , rowspan=2, 41(17) ms , α , ¹⁹⁹Rn , rowspan=2, (13/2+) , rowspan=2, , - , β⁺ (rare) , ²⁰³Fr , - , rowspan=2, ²⁰⁴Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 116 , rowspan=2, 204.006500(17) , rowspan=2, 60(11) ms
9(+12−9) ms, α (99.7%) , ²⁰⁰Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (.3%) , ²⁰⁴Fr , - , rowspan=2, ²⁰⁵Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 117 , rowspan=2, 205.00627(9) , rowspan=2, 220(40) ms
10(+60−40) ms, α , ²⁰¹Rn , rowspan=2, (3/2−) , rowspan=2, , - , β⁺ (rare) , ²⁰⁵Fr , - , rowspan=2 style="text-indent:1em" , ^205mRa , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 310(110)# keV , rowspan=2, 180(50) ms
70(+60−40) ms, α , ²⁰¹Rn , rowspan=2, (13/2+) , rowspan=2, , - , IT (rare) , ²⁰⁵Ra , - , ²⁰⁶Ra , , style="text-align:right" , 88 , style="text-align:right" , 118 , 206.003827(19) , 0.24(2) s , α , ²⁰²Rn , 0+ , , - , rowspan=2, ²⁰⁷Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 119 , rowspan=2, 207.00380(6) , rowspan=2, 1.3(2) s , α (90%) , ²⁰³Rn , rowspan=2, (5/2−, 3/2−) , rowspan=2, , - , β⁺ (10%) , ²⁰⁷Fr , - , rowspan=3 style="text-indent:1em" , ^207mRa , rowspan=3, , rowspan=3 colspan="3" style="text-indent:2em" , 560(50) keV , rowspan=3, 57(8) ms , IT (85%) , ²⁰⁷Ra , rowspan=3, (13/2+) , rowspan=3, , - , α (15%) , ²⁰³Rn , - , β⁺ (.55%) , ²⁰⁷Fr , - , rowspan=2, ²⁰⁸Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 120 , rowspan=2, 208.001840(17) , rowspan=2, 1.3(2) s , α (95%) , ²⁰⁴Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (5%) , ²⁰⁸Fr , - , style="text-indent:1em" , ^208mRa , , colspan="3" style="text-indent:2em" , 1800(200) keV , 270 ns , , , (8+) , , - , rowspan=2, ²⁰⁹Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 121 , rowspan=2, 209.00199(5) , rowspan=2, 4.6(2) s , α (90%) , ²⁰⁵Rn , rowspan=2, 5/2− , rowspan=2, , - , β⁺ (10%) , ²⁰⁹Fr , - , rowspan=2, ²¹⁰Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 122 , rowspan=2, 210.000495(16) , rowspan=2, 3.7(2) s , α (96%) , ²⁰⁶Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (4%) , ²¹⁰Fr , - , style="text-indent:1em" , ^210mRa , , colspan="3" style="text-indent:2em" , 1800(200) keV , 2.24 μs , , , (8+) , , - , rowspan=2, ²¹¹Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 123 , rowspan=2, 211.000898(28) , rowspan=2, 13(2) s , α (97%) , ²⁰⁷Rn , rowspan=2, 5/2(−) , rowspan=2, , - , β⁺ (3%) , ²¹¹Fr , - , rowspan=2, ²¹²Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 124 , rowspan=2, 211.999794(12) , rowspan=2, 13.0(2) s , α (85%) , ²⁰⁸Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (15%) , ²¹²Fr , - , style="text-indent:1em" , ^212m1Ra , , colspan="3" style="text-indent:2em" , 1958.4(5) keV , 10.9(4) μs , , , (8)+ , , - , style="text-indent:1em" , ^212m2Ra , , colspan="3" style="text-indent:2em" , 2613.4(5) keV , 0.85(13) μs , , , (11)− , , - , rowspan=2, ²¹³Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 125 , rowspan=2, 213.000384(22) , rowspan=2, 2.74(6) min , α (80%) , ²⁰⁹Rn , rowspan=2, 1/2− , rowspan=2, , - , β⁺ (20%) , ²¹³Fr , - , rowspan=2 style="text-indent:1em" , ^213mRa , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 1769(6) keV , rowspan=2, 2.1(1) ms , IT (99%) , ²¹³Ra , rowspan=2, 17/2−# , rowspan=2, , - , α (1%) , ²⁰⁹Rn , - , rowspan=2, ²¹⁴Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 126 , rowspan=2, 214.000108(10) , rowspan=2, 2.46(3) s , α (99.94%) , ²¹⁰Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (.06%) , ²¹⁴Fr , - , ²¹⁵Ra , , style="text-align:right" , 88 , style="text-align:right" , 127 , 215.002720(8) , 1.55(7) ms , α , ²¹¹Rn , (9/2+)# , , - , style="text-indent:1em" , ^215m1Ra , , colspan="3" style="text-indent:2em" , 1877.8(5) keV , 7.1(2) μs , , , (25/2+) , , - , style="text-indent:1em" , ^215m2Ra , , colspan="3" style="text-indent:2em" , 2246.9(5) keV , 1.39(7) μs , , , (29/2−) , , - , style="text-indent:1em" , ^215m3Ra , , colspan="3" style="text-indent:2em" , 3756.6(6)+X keV , 0.555(10) μs , , , (43/2−) , , - , rowspan=2, ²¹⁶Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 128 , rowspan=2, 216.003533(9) , rowspan=2, 182(10) ns , α , ²¹²Rn , rowspan=2, 0+ , rowspan=2, , - , EC (1×10⁻⁸%) , ²¹⁶Fr , - , ²¹⁷Ra , , style="text-align:right" , 88 , style="text-align:right" , 129 , 217.006320(9) , 1.63(17) μs , α , ²¹³Rn , (9/2+) , , - , rowspan=2, ²¹⁸Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 130 , rowspan=2, 218.007140(12) , rowspan=2, 25.2(3) μs , α , ²¹⁴Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺β⁺ (rare) , ²¹⁸Rn , - , ²¹⁹Ra , , style="text-align:right" , 88 , style="text-align:right" , 131 , 219.010085(9) , 10(3) ms , α , ²¹⁵Rn , (7/2)+ , , - , ²²⁰Ra , , style="text-align:right" , 88 , style="text-align:right" , 132 , 220.011028(10) , 17.9(14) ms , α , ²¹⁶Rn , 0+ , , - , rowspan=2, ²²¹Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 133 , rowspan=2, 221.013917(5) , rowspan=2, 28(2) s , α , ²¹⁷Rn , rowspan=2, 5/2+ , rowspan=2, TraceIntermediate decay product of ²³⁷Np , - , CD (1.2×10⁻¹⁰%) , ²⁰⁷Pb
¹⁴C , - , rowspan=2, ²²²Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 134 , rowspan=2, 222.015375(5) , rowspan=2, 38.0(5) s , α , ²¹⁸Rn , rowspan=2, 0+ , rowspan=2, , - , CD (3×10⁻⁸%) , ²⁰⁸Pb
¹⁴C , - , rowspan=2, ²²³RaUsed for treating bone cancer , rowspan=2, Actinium X , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 135 , rowspan=2, 223.0185022(27) , rowspan=2, 11.43(5) d , α , ²¹⁹Rn , rowspan=2, 3/2+ , rowspan=2, TraceIntermediate

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( ...

of ²³⁵U , - , CD (6.4×10⁻⁸%) , ²⁰⁹Pb
¹⁴C , - , rowspan=2, ²²⁴Ra , rowspan=2, Thorium X , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 136 , rowspan=2, 224.0202118(24) , rowspan=2, 3.6319(23) d , α , ²²⁰Rn , rowspan=2, 0+ , rowspan=2, TraceIntermediate decay product of ²³²Th , - , CD (4.3×10⁻⁹%) , ²¹⁰Pb
¹⁴C , - , ²²⁵Ra , , style="text-align:right" , 88 , style="text-align:right" , 137 , 225.023612(3) , 14.9(2) d , β⁻ , ²²⁵Ac , 1/2+ , TraceIntermediate decay product of ²³⁷Np , - , rowspan=3, ²²⁶Ra , rowspan=3, RadiumSource of element's name , rowspan=3 style="text-align:right" , 88 , rowspan=3 style="text-align:right" , 138 , rowspan=3, 226.0254098(25) , rowspan=3, 1600(7) y , α , ²²²Rn , rowspan=3, 0+ , rowspan=3, TraceIntermediate decay product of ²³⁸U , - , β⁻β⁻ (rare) , ²²⁶Th , - , CD (2.6×10⁻⁹%) , ²¹²Pb
¹⁴C , - , ²²⁷Ra , , style="text-align:right" , 88 , style="text-align:right" , 139 , 227.0291778(25) , 42.2(5) min , β⁻ , ²²⁷Ac , 3/2+ , , - , ²²⁸Ra , Mesothorium 1 , style="text-align:right" , 88 , style="text-align:right" , 140 , 228.0310703(26) , 5.75(3) y , β⁻ , ²²⁸Ac , 0+ , Trace , - , ²²⁹Ra , , style="text-align:right" , 88 , style="text-align:right" , 141 , 229.034958(20) , 4.0(2) min , β⁻ , ²²⁹Ac , 5/2(+) , , - , ²³⁰Ra , , style="text-align:right" , 88 , style="text-align:right" , 142 , 230.037056(13) , 93(2) min , β⁻ , ²³⁰Ac , 0+ , , - , ²³¹Ra , , style="text-align:right" , 88 , style="text-align:right" , 143 , 231.04122(32)# , 103(3) s , β⁻ , ²³¹Ac , (5/2+) , , - , style="text-indent:1em" , ^231mRa , , colspan="3" style="text-indent:2em" , 66.21(9) keV , ~53 μs , , , (1/2+) , , - , ²³²Ra , , style="text-align:right" , 88 , style="text-align:right" , 144 , 232.04364(30)# , 250(50) s , β⁻ , ²³²Ac , 0+ , , - , ²³³Ra , , style="text-align:right" , 88 , style="text-align:right" , 145 , 233.04806(50)# , 30(5) s , β⁻ , ²³³Ac , 1/2+# , , - , ²³⁴Ra , , style="text-align:right" , 88 , style="text-align:right" , 146 , 234.05070(53)# , 30(10) s , β⁻ , ²³⁴Ac , 0+ ,

Actinides vs fission products

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Authority control Radium