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Det er ikke-metallisk og tetravalent — hvilket vil sige, at det gør fire elektroner tilgængelige til at danne kovalente kemiske bindinger.Tre isotoper findes naturligt: Carbon er det femtende mest forekommende element i Jordens skorpe og det fjerde mest forekommende element i universet (sorteret efter masse) efter hydrogen, helium og oxygen.The simplest form of isotopic age computation involves substituting three measurements into an equation of four variables, and solving for the fourth.The equation is the one which describes radioactive decay: If one of these assumptions has been violated, the simple computation above yields an incorrect age.Note that the mere existence of these assumptions do not render the simpler dating methods entirely useless.In many cases, there are independent cues (such as geologic setting or the chemistry of the specimen) which can suggest that such assumptions are entirely reasonable.However, the methods must be used with care -- and one should be cautious about investing much confidence in the resulting age...especially in absence of cross-checks by different methods, or if presented without sufficient information to judge the context in which it was obtained.
In addition, it requires that these measurements be taken from several different objects which all formed at the same time from a common pool of materials.This is calculated through careful measurement of the residual activity (per gram C) remaining in a sample whose age is Unknown, compared with the activity present in Modern and Background samples. Thus 1950, is year 0 BP by convention in radiocarbon dating and is deemed to be the 'present'.You can get an idea of the relationship between C14 and age at the Carbon Dating calculator page. 1950 was chosen for no particular reason other than to honour the publication of the first radiocarbon dates calculated in December 1949 (Taylor, 19).The Oxalic acid standard was made from a crop of 1955 sugar beet. The isotopic ratio of HOx I is -19.3 per mille with respect to (wrt) the PBD standard belemnite (Mann, 1983). T designation SRM 4990 C) was made from a crop of 1977 French beet molasses.The Oxalic acid standard which was developed is no longer commercially available. In the early 1980's, a group of 12 laboratories measured the ratios of the two standards.