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Carbon elemental, electron

Organic chemistry, then, is the study of carbon compounds. But why is carbon special Why, of the more than 30 million presently known chemical compounds, do more than 99% of them contain carbon The answers to these questions come from carbon s electronic structure and its consequent position in the periodic table (Figure 1.1). As a group 4A element, carbon can share four valence electrons and form four strong covalent bonds. Furthermore, carbon atoms can bond to one another, forming long chains and rings. Carbon, alone of all elements, is able to form an immense diversity of compounds, from the... [Pg.3]

The primary consideration for all AEM analysis is that the specimen be thin (generally carbon coated electron microscope grid either dry or in a suitable liquid. If a liquid suspension is used in preparing the specimen, it is important that all elements of interest are insoluble in that liquid. Only particles thin enough to meet AEM thin-film criteria (15) should be analyzed quantitatively. Scraping surface particles from a catalyst pellet for specimen preparation may be more useful than grinding the entire pellet. [Pg.365]

The compounds of lithium and magnesium are the most important of the group IA and IIA organometallics from a synthetic perspective. The metals in these two groups are the most electropositive of the elements. The polarity of the metal-carbon bond is such as to place high electron density on carbon. This electronic distribution is responsible for the strong nucleophilicity and basicity of these compounds. [Pg.433]

Symbol Sn atomic number 50 atomic weight 118.69 a Group IV A (Group 14) metaUic element of carbon family electron configuration Kr] 4di°5s25p2 valence states +2, +4 atomic radius 1.41 A electronegativity 1.7 standard electrode potential, E° for Sn2+ -i- 2e Sn is -0.1375 V ten naturally-occurring sta-... [Pg.934]

The importance of identifying the electrophile and the nucleophile in organic reactions cannot be overemphasized. The electrophile is usually a carbon bonded to an electronegative element so that the carbon is electron deficient. The nucleophile most often contains an atom with an unshared pair of electrons, a Lewis base. In this chapter the electrophilic carbon is the one bonded to a leaving group. A few nucleophiles have been presented, but many more will be discussed in Chapter 10. Later chapters will introduce new electrophiles or new nucleophiles, but the new reactions always involve the nucleophile forming a bond to the electrophile. [Pg.301]

When one (or more) hydrogen atom(s) of the polyethylene monomeric unit is (are) replaced by a heteroatom, an aliphatic or an aromatic group, modifications are induced in the valence band spectrum new peaks, band shift and/or splitting, redistribution of the electronic population among the molecular orbitals will denote the new bonds created in the molecule. Similar effects will be observed for the insertion of heteroatom(s) between two carbon elements of the polymer skeleton. [Pg.179]

The one perspective field of researches for a probe nanotechnology is a development of carbon-based electronic elements. Carbon has found wide application in electronics and nuclear technology because of high thermal and radiation resistance. The methods of conventional planar microelectronics can be combined with probe technology for production of totally integrated carbon devices. [Pg.464]

For reaction (a) to proceed, the Y group must form a stable Li salt. The reactivity of a carbon-element bond in Eq. (a) may be estimated by the acidity of the add, HY. Therefore, the ease of cleaving representative substrates by Li rank RCl > RSCgH > ROCgHj > RP(CgH5)2. However, even C—C bonds can be cleaved by Li when both carbon atoms contain electron-withdrawing groups. [Pg.53]

CARBON is the sixth element of the Periodic Table of Elements (electronic ground state... [Pg.1135]


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