Half Life - Law Dictionary Search Results
Home Dictionary Name: half lifeHalf life
the time it takes for one half of a substance decaying in a first order reaction to be destroyed For radioactive substances it is the time required for one half of the initial amount of the radioactive isotope to decay The half lifeis a measure of the rate of the reaction being observed For processes that are true first order processes such as radioactive decay the half life is independent of the quantity of material present and it is thus a constant The time it takes for one half the remaining quantity of a radioactive isotope to decay will be the same regardless of how far the decay process has advanced Some chemical reactions are also first order and may be characterized as having a half life However for chemical reactions the half life will depend upon temperature and in some cases other environmental conditions whereas for radioactive isotopes the rate of decay is largely independent of the environment...
Mesothorium
a radioactive isotope of radium radium 228 with a half life of 58 years Also called mesothorium 1 or mesothorium I to distinguish it from a subsequent decay product mesothorium II actinium 228 It was discovered in 1907 by Otto Hahn as a decay product of thorium produced by decay of thorium 232 Mesothorium 1 radium 228 in turn produces actinium 228 mesothorium 2 as the first product of its radioactive decay and the actinium 228 in turn decays quickly half life of 6 hours to thorium 228 which is also called radiothorium the thorium 228 has a half life of 191 years shorter than that of the radium 228 It was discovered and named before full recognition of the nature of isotopes of the elements and was distinguished from other variants of radium by its half life and mode of production and decay It was also cheaper to prepare than other short lived radium isotopes and was thus sold commercially for use eg in making watch dials readable in the dark by painting the hands and hour marks with a ...
kurchatovium
A transuranic element of atomic number 104 symbol Ku also called rutherfordium symbol Rf It is produced in very small quantities by nuclear reactions In November 1993 the nomenclature committe of the American Chemical Society approved the name rutherfordium for element 104 Russsian investigators who claim to have first discovered element 104 isotope 260 half life 03 seconds in 1964 at Dubna proposed the name kurchatovium However investigators at Berkely in 1969 produced several isotopes of element 104 but were unable to produce isotope 260 they reported finding isotope 257 with a half life of 4 5 seconds isotope 259 with a half life of 3 4 seconds and isotope 258 with a shorter half life...
berkelium
a chemical element of the transuranic series Chemical symbol Bk atomic number 97 atomic weight 247 It is a radioactive element with no stable isotopes the longest lived isotope is of mass number 24707 decaying by alpha emission with a half life of 1400 years The isotope with atomic weight 249 has a half life of 314 days and was isolated in weighable quantities...
Es
the chemical symbol for einsteinium a transuranic element with atomic number 99 The atomic weight of the longest lived isotope with a half life of 276 days is 254 The first isotope discovered having atomic weight 253 and a half life of 20 days was recognized in 1952 in the debris from a hydrogen bomb test As much as 3 micrograms of einsteinium were produced by a complex process involving long irradiation of plutonium isotopes in nuclear reactors Its chemical properties are those of a trivalent actinide element...
Term, imprisonment for life and imprisonment for a term
Term, imprisonment for life and imprisonment for a term, the word 'term' does not necessarily imply a concept of ascertainability or conveys a sense of certainty. s. 53, 53-A(4) and (b), 57 or 65 IPC do not militate against this conclusion, nor the words 'for a term which may extend to one half of the imprisonment for life' in s. 511, IPC support this conclusion. The expressions 'imprisonment for life' and 'imprisonment for a term' are not used either in the Penal Code or in the Criminal Procedure Code in contradistinction with each other, Bhagirath v. Delhi Administration, AIR 1985 SC 1050 (1052): (1985) 2 SCC 580: (1985) 3 SCR 743....
Radon
An intensely radioactive gaseous element produced by the radioactive decay of radium 226 which is the main isotope of radium found in pitchblende Chemically it is an inert noble gas Its atomic symbol is Rn It has an atomic number of 86 The radon isotope produced by decay of radium has an atomic weight of 222017 and this isotope decays by alpha emission with a half life of 382 days Numerous other isotopes have been observed all radioactive and all having half lives shorter than that of radon 222 Radon was discovered by M and Mme Curie of Paris in their studies of the radioactive substances in pitchblende Radon was originally called radium emanation or exradio...
carbon 14
a radioactive isotope of carbon with a half life of 5730 years It occurs naturally in minute quantities and is used as the basis for radiocarbon dating...
curium
a radioactive transuranic element of atomic number 96 having an atomic weight of 247 for its most stable isotope half life 16 x 107 years The chemical symbol is Cm...
fermium
the transuranic element of atomic number 100 symbol Fm The atomic weight of the most stable isotope having a half life of about 80 days is 257 The first isotope Fm255 was discovered in 1952 in the debris of a thermonuclear explosion Other istopes have been produced in nuclear reactors and by decay of other transuranic elements...
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