Search results
Results from the WOW.Com Content Network
In a chemical reaction, the half-life of a species is the time it takes for the concentration of that substance to fall to half of its initial value. In a first-order reaction the half-life of the reactant is ln(2)/λ, where λ (also denoted as k) is the reaction rate constant.
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
Mercury (as methylmercury) in the body has a half-life of about 65 days. Lead in the blood has a half life of 28–36 days. [29] [30] Lead in bone has a biological half-life of about ten years. Cadmium in bone has a biological half-life of about 30 years. Plutonium in bone has a biological half-life of about 100 years.
Deuterium is often represented by the chemical symbol D. Since it is an isotope of hydrogen with mass number 2, it is also represented by 2 H. IUPAC allows both D and 2 H, though 2 H is preferred. [8] A distinct chemical symbol is used for convenience because of the isotope's common use in various scientific processes.
In total, barium has 40 known isotopes, ranging in mass between 114 and 153. The most stable artificial radioisotope is barium-133 with a half-life of approximately 10.51 years. Five other isotopes have half-lives longer than a day. [16] Barium also has 10 meta states, of which barium-133m1 is the most stable with a half-life of about 39 hours ...
[24] [25] Thirty additional rubidium isotopes have been synthesized with half-lives of less than 3 months; most are highly radioactive and have few uses. [26] Rubidium-87 has a half-life of 48.8 × 10 9 years, which is more than three times the age of the universe of (13.799 ± 0.021) × 10 9 years, [27] making it a primordial nuclide.
Iron-60 has a half-life of 2.6 million years, [12] [13] but was thought until 2009 to have a half-life of 1.5 million years. It undergoes beta decay to cobalt-60, which then decays with a half-life of about 5 years to stable nickel-60. Traces of iron-60 have been found in lunar samples.
The half-life of 239 Np is very short, ... Dmitri Mendeleev's table of 1871, ... Though its chemical formula in basic solution is frequently cited as NpO 3 ...