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231 Th has 141 neutrons. It is the decay product of uranium-235. It is found in very small amounts on the earth and has a half-life of 25.5 hours. [53] When it decays, it emits a beta ray and forms protactinium-231. It has a decay energy of 0.39 MeV. It has a mass of 231.0363043 u.
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Its decay product, 231 Pa, gradually precipitates to the bottom, so that its concentration first increases with depth and then stays nearly constant. 231 Pa decays to 227 Ac; however, the concentration of the latter isotope does not follow the 231 Pa depth profile, but instead increases toward the sea bottom.
Formula color symmetry space group No Pearson symbol a (pm) b (pm) c (pm) Z density, g/cm 3; Ac silvery fcc [31] Fm 3 m 225 cF4 531.1 531.1 531.1 4 10.07 AcH 2: unknown cubic [31] Fm 3 m 225 cF12 567 567 567 4 8.35 Ac 2 O 3: white [17] trigonal [32] P 3 m1 164 hP5 408 408 630 1 9.18 Ac 2 S 3: black cubic [33] I 4 3d 220 cI28 778.56 778.56 778. ...
Chemical formula Synonyms CAS number CAgO carbonylsilver: CCl 2 F 2: dichlorodifluoromethane freon-12: 75-71-8 CCl 4: carbon tetrachloride tetrachloromethane: 56-23-5 C(CN) 4: tetracyanomethane: 24331-09-7 CFCl 3: trichlorofluoromethane freon-11: 75-69-4 CFCl 2 CF 2 Cl: chlorotrifluoromethane freon-13: 75-72-9 CHCl 3: chloroform ...
Chemical substance – Form of matter; Inorganic compounds by element; List of alloys; List of alkanes; List of elements by name; List of minerals – List of minerals with Wikipedia articles; List of alchemical substances; Polyatomic ion – Ion containing two or more atoms; Exotic molecules – Atoms composed of exotic particles can form ...
In chemistry, the mass fraction of a substance within a mixture is the ratio (alternatively denoted ) of the mass of that substance to the total mass of the mixture. [1] Expressed as a formula, the mass fraction is:
Protactinium-231 arises naturally from the decay of natural uranium-235, and artificially in nuclear reactors by the reaction 232 Th + n → 231 Th + 2n and the subsequent beta decay of 231 Th. It was once thought to be able to support a nuclear chain reaction, which could in principle be used to build nuclear weapons ; the physicist Walter ...