Ch4_Prelim_Fab - Preliminary Fabrication 1 Chapter Four...

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Preliminary Fabrication 1 Chapter Four Preliminary Fabrication: Organic and Inorganic In stellar interiors all the important reactions involve the nuclei themselves, as one atom is transformed to another. Outside of stars, energies fall by orders of magnitude and a different set of laws operates. Atoms become the fundamental, unchangeable building block of matter. The number of protons in the tiny nucleus of the atom controls the number of electrons required for charge balance, and this electron cloud extends 100,000 times farther than the size of the nucleus preventing neighboring nuclei from interacting directly. Interactions among atoms thus become in- teractions between the electron clouds. The laws of electron cloud interaction control the formation of molecules in interstellar space, the formation of planets and all the processes that subsequently take place on them. With the exception of the infl uence of cosmic rays emanating from stars, and the rare radioactive nuclides that retain the vestiges of their stellar origin, everything that happens on earth deals with reactions among the electron clouds. For stars and atomic chemistry, the funda- mental unit was the nucleus that made an isotope with a single mass, and the chart that summarized our knowledge was the Chart of the Nuclides. For planets, the fundamental control lies in the con- ± guration of the electron clouds--elements become the fundamental chemical substance, and the Periodic Table, organized around electron shell structure and with all isotopes of the same element combined, presents in concise form the fundamental organization and principles. Atoms combine to form molecules, and almost all the chemical reactions we deal with involve interactions among molecules. The ± rst molecular building blocks are constructed in the vast clouds of interstellar space to form the inorganic molecules known as minerals, and also the simplest organic molecules. The minerals will become the building blocks for solid planets, and the organic molecules will contribute to larger, gaseous planets and also serve as the ± rst building blocks for life. Our discussions in Chapter 2 dealt with processes at the exceedingly high temperatures of millions of degrees appropriate to stellar interiors. At these temperatures the positively charged nu- clei have such high velocities that they collide and react, following the laws of nuclear physics. At this stellar level, events that are impossible based on our human experience become normal. Atoms are created and destroyed, no molecules exist, there are no such things as rocks or minerals; life as we conceive of it is impossible. Outside this stellar realm, temperatures drop from millions of degrees to less than thou- sands of degrees. At these temperatures the positively charged nuclei are much less energetic and become surrounded by negatively charged electron shells. The atomic chemistry of stellar interiors is no longer applicable, and we arrive in the realm of the “normal
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This note was uploaded on 02/08/2011 for the course EAS 1601 taught by Professor Lynch during the Spring '08 term at Georgia Tech.

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Ch4_Prelim_Fab - Preliminary Fabrication 1 Chapter Four...

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