Main Group Chemistry - Main Group Chemistry An Introduction...

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Main Group Chemistry An Introduction We have spent the better part of the school year developing physical models to describe atomic structure, chemical bonding and the thermodynamics and kinetics physical and chemical phenomena. In all of that, however, we have been just as content to use generic symbols like A + B Æ C + D or to describe a weak acid as HA, as to actually assign it a real chemical structure with real chemical reactivity. In this chapter we right this wrong, working systematically through the main groups of the periodic table, learning for each group and particularly significant elements in those groups: The natural forms in which the elements are found, including the hydrides and oxides The famous chemical reactions that involve the chemical compounds containing those elements The important practical uses of the compounds containing those elements.
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Common themes in Main Group Chemistry: We must have learned something useful during the year that will help to explain the chemistry of the main group elements. Here are some important themes that appear to explain pretty much everything that happens 1. The number of valence electrons in atoms drive the chemistry of a compound. And the main group number corresponds to the number of valence electrons 2. Compounds formed by main group elements pretty much always satisfy the octet rule if they can, achieving noble gas- like electronic configurations 3. There are trends in the periodic table that are pretty much determined by the effective nuclear charge and overall number of electrons in an atom. These trends are: a) atomic radius decreases moving to the right and up the periodic table b) ionization energy increases moving to the right and up the periodic table c) electronegativity increases to the right and up the periodic table d) polarizability increases to the right and down the periodic table e) non-metallic character increases to the right and up the periodic table 4. The second row of the periodic table is very special because overlap of adjacent 2p orbitals creates & bonding and because the significance of intermolecular hydrogen bonding forces. In contrast, third and higher rows create expanded orbitals to accommodate additional electrons in mushy low energy bonds.
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5. Pretty much every element except the noble gases forms very stable compounds with itself, whether through metallic bonding, network solids like C, or small covalent molecules like N 2 or P 4 . 6. Pretty much every compound forms hydrides (reacts with hydrogen. Basic ioni c hydrides like NaH are found to the left on the periodic table and increasingly covalent acidic hydrides like HCl are found to the right on the periodic table. 7.
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Main Group Chemistry - Main Group Chemistry An Introduction...

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