Search results
Results From The WOW.Com Content Network
Specific activity (symbol a) is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. [ 1 ] [ 2 ] It is usually given in units of becquerel per kilogram (Bq/kg), but another commonly used unit of specific activity is the curie per gram (Ci/g).
The decay-chain of uranium-238, which contains radium-226 as an intermediate decay product. 226 Ra occurs in the decay chain of uranium-238 (238 U), which is the most common naturally occurring isotope of uranium. It undergoes alpha decay to radon-222, which is also radioactive; the decay chain ultimately terminates at lead-206.
Radium (88 Ra) has no stable or nearly stable isotopes, and thus a standard atomic weight cannot be given. The longest lived, and most common, isotope of radium is 226 Ra with a half-life of 1600 years. 226 Ra occurs in the decay chain of 238 U (often referred to as the radium series). Radium has 34 known isotopes from 201 Ra to 234 Ra.
Because of its relative longevity, 226 Ra is the most common isotope of the element, making up about one part per trillion of the Earth's crust; essentially all natural radium is 226 Ra. [29] Thus, radium is found in tiny quantities in the uranium ore uraninite and various other uranium minerals, and in even tinier quantities in thorium minerals.
It was originally defined as "the quantity or mass of radium emanation in equilibrium with one gram of radium (element)", [1] but is currently defined as 1 Ci = 3.7 × 10 10 decays per second [4] after more accurate measurements of the activity of 226 Ra (which has a specific activity of 3.66 × 10 10 Bq/g [5]).
The most stable isotope is 222 Rn (half-life 3.82 days), which is a decay product of 226 Ra, the latter being itself a decay product of 238 U. [41] A trace amount of the (highly unstable) isotope 218 Rn (half-life about 35 milliseconds) is also among the daughters of 222 Rn.
Download QR code; Print/export Download as PDF; ... 218 At, 223 Ra, 224 Ra, 225 Ra, and 226 Ra. 217 Rn and 221 Rn are produced in rare branches in the decay chain of ...
Radium 88 Ra [226] Lawrencium 103 Lr [266] Rutherfordium 104 Rf [267] Dubnium 105 Db [268] Seaborgium 106 Sg [269] Bohrium 107 Bh [270] Hassium 108 Hs [271] Meitnerium 109 Mt [278] Darmstadtium 110 Ds [281] Roentgenium 111 Rg [282] Copernicium 112 Cn [285] Nihonium 113 Nh [286] Flerovium 114 Fl [289] Moscovium 115 Mc ...