Origin of elements

The nucleus of an element consists of two main building blocks the proton and the neutron. It is the proportions, in which the two nucleons are joined in nucleonic packs termed nuclei which give rise to the various chemical elements and their isotopes. We believe that the essential protons and neutrons needed for the synthesis of chemical elements were generated when the Universe was just a few seconds old. The existing temperature at that time, about 10 K, enabled neutrons to decouple. Further, neutrons and protons react with each other. Calculations showed that among the stable nuclei generated in the first 3 min were deuterium, helium-3, helium-4 and lithium-7. However, due to lack of stable nuclei at mass numbers 5 and 8, the heavier elements could not be created during this enter period. 

The succession of element formation can best be followed by moving up the temperature scale from a modest few million degrees to several billion degrees (Degens, 1989). It is shown schematically in Eigure 1. 

Examples of reactions proceeding during stellar nucleosynthesis are shown in Table 1. To illustrate the sequence of events, the decay series of uranium-238 is depicted in this table. Radiogenic nuclides decay by the emission of alpha, beta and gamma radiation or by electron capture into so called daughter nuclides at their half-lives. This half-life ranges from parts of seconds to billions of years. 

The time required for the synthesis of all elements in cosmic abundance also ranges from seconds to billions of years. The temperature scales fluctuate over several orders of magnitude (see Eigure 1). The chemical composition of the Universe, excepting the matter of neutron stars and black holes , can be presented as follows of 1,000,000 atoms there are 924,400 hydrogen, 74,000 helium, 830 oxygen. 

470 carbon, 84 nitrogen, 82 neon, 35 magnesium, 33 silicon, 32 iron, 18 sulfur, 8 argon, 3 aluminum, 3 calcium, and the remaining 2 atoms for the rest of the elements (Degens, 1989). 

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Electron structure Radius (pm) Color of Origin of element name... 

Spears, D. A. Zheng, Y. 1999. Geochemistry and origin of elements in some UK coals. International Journal of Coal Geology, 38, 161-179. 

Viola, V. E. LiBeB Nucleosynthesis and Clues to the Chemical Evolution of the Universe, in O. Manuel, Ed., Origin of Elements in the Solar System Implications of Post-1957 Observations, Kluwer, New York, 2000. 

In the third part of the conference, on the Evolution of Galaxies and Stars, Hoyle presented the then recent and still important work by the Burbidges, Fowler, and himself on the origin of elements in stars.102... 

Discovery Date Name Sym z Discoverer Discovery Location Meaning and origin of element names... 

Origin of Elemental composition (%) C/N Ash Acidic functional groups (meqg ... 

Gilmour JD, Whitby JA, Turner G (1998) Xenon isotopes in irradiated ALH84001 Evidence for shock-induced trapping of ancient Martian atmosphere. Geochim Cosmochim Acta 62 2555-2571 Gilmour JD, Whitby JA, Turner G (1999) Martian atmospheric xenon contents of Nakhla mineral separates Implications for the origin of elemental mass fractionation. Earth Planet Sci Lett 166 139-147... 

Griffin, . J. E. D. Goldberg, 1979. Morphologies and origin of elemental carbon in the environment. Science 206 563-565. 

But in this respect nuclear physics proved to be a foe of natural promethium. With each newly synthesized promethium isotope a possible scope for search became increasingly narrow. The promethium isotopes were found to be short-lived. Among the fifteen promethium isotopes known today the longest-lived one has a half-life of only 30 years. In other words, when Earth had just formed as a planet not a trace of promethium could exist on it. But what we mean here is the primary promethium formed in the primordial process of origination of elements. What was discussed was the search for the secondary promethium which is still being formed on Earth in various natural nuclear reactions. 

Gamow G (1946) Expanding universe and the origin of elements. Phys Rev 70 572... 

In VoL 2 of this handbook, the origin of elements has been discussed in detail. Therefore, the present authors will exclude that part, except for some comments on the importance of particular radionucKdes. In this chapter, the principles and instrumentation of accelerator mass spectrometry (AMS), the key player for detection of cosmological radionucKdes in ultra trace scale, will be discussed in detail. Detailed discussion of all the research works carried out to date with cosmogenic radionuclides is out of scope. Only the detection of million-year half-life radionucKdes in ultra trace concentration will be touched, followed by concise description of the required chemistry. Rather than giving a general description, a few of them have been chosen and described in separate sections. Inductively coupled plasma-mass spectrometry (ICP-MS), thermal ionization mass spectrometry (TIMS), secondary ion mass spectrometry (SIMS), or resonant laser ionization mass spectrometer (RIMS), etc. have also been used for detection of cosmogenic radionucKdes. However, these techniques have much lower sensitivity compared to AMS. Brief discussions on these instruments have been appended at the end of this chapter. This chapter ends with a conclusion. 

Proof of the true origin of elemental oxygen generated in photosynthesis was presented some time ago by Kamen in experiments with isotopically labeled water, Ha K). 

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