Negative charge atom bearing

Oxygen atoms in a zeolite lattice have an intrinsic Lewis base character due to the electron pairs they can donate and to the partial negative charges they bear. Silicon or aluminum atoms provide partial positive charges, which reduce the strength of such a donation [8,54]. However, every zeolite framework possesses an intrinsic Lewis base character. Additional basic sites can be created by metal or metal oxide clusters within the micropores of the zeolite [54]. The different basic sites will be discussed in the following paragraphs. 

Lewis structures frequently contain atoms that bear a positive or negative charge If the molecule as a whole is neutral the sum of its positive charges must equal the sum of Its negative charges An example is nitric acid HNO3... 

Among structural formulas in which the octet rule IS satisfied for all atoms and one or more of these atoms bears a formal charge the most stable reso nance form is the one in which negative charge re sides on the most electronegative atom... 

As we saw in Section 1 15 the ability of an atom to bear a negative charge is related to its electronegativity Both the electronegativity of an atom X and the acidity of H—X increase across a row m the periodic table... 

However, reaction of 218 (E = P, R = R = H, R = r" = Me) with rerr-butyl-lithium most probably yields 221. The phospholyl loses its electrophilicity and the iron atom bears a considerable negative charge. Addition of rerr-butyllithium (one equivalent) followed by methyl iodide (one equivalent) does not give any isolable product but leads to recovery of the starting 218 only. In excess tert-butyllithium and methyliodide, 222 (R = r-Bu, R = Me) was isolated (81IC3252). 

You have been told that the atomic nucleus bears a positive charge and is surrounded by a number of negatively charged particles called electrons. Also, the nucleus is supposed to contain most of the mass of the atom and to be made of protons and neutrons, each of which has nearly two thousand times the mass of the electron. How do we know that atoms are built this way How do we know that there is such a particle as an electron Again, weight relations associated with chemical reactions provide key evidence. 

Quinoxaline (see Section 2.1.3) and many of its derivatives may be converted into A-alkylquimoxalinium or even A,A -dialkylquinoxalinediium salts by treatment with alkyl halides or the like. Occasionally, when the molecule bears a suitable acidic grouping, it may be possible to deprive the quaternary salt of its gegenion by treatment with a base to form an ylide (in which a carbon atom of the molecule bears the negative charge) or other zwitterionic entity, such as a quinoxaliniumolate. 

Carbanion Chemical moiety bearing a negative charge on a carbon atom. 

For molecules with low polarity like hydrocarbons, electrostatic forces have only a minor influence. Molecules with highly polar bonds behave as dipoles or multipoles and exhibit corresponding interactions. For instance, hexahalide molecules like WF6 or WC16 are multipoles, the halogen atoms bearing a negative partial charge -q, while the metal... 

Some nonmetals form complex (polyatomic) anions, which consist of a group of three or more atoms bearing a negative charge. 

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