Covalent Compounds and Organic Molecules

It is assumed that you have fully understood the principles outlined in Chapter 1. 

Try this short test. If you score more than 80 % you can use the chapter as a revision of your knowledge. If you score less than 80 % you probably need to work through the text and test yourself again at the end using the same test. If you still score less than 80 % then come back to the chapter after a few days and read it again. 

Chemistry An Introduction for Medical and Health Sciences, A. Jones 2005 John Wiley Sons, Ltd 

What is the bonding called where the electrons are shared between atoms  

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The dimensionality of the space spanned by covalent states is much less than the full number of basis states of the Hubbard model. This is one of the reasons of the success in the application of the above VB Hamiltonians to the study of low-lying energy levels of the transition metal compounds and organic molecules with conjugated bonds. The covalent VB approach is very useful especially for predictions as to ground state spin multiplicity and spin ordering [14,17-20],... 

Lewis acids are defined as molecules that act as electron-pair acceptors. The proton is an important special case, but many other species can play an important role in the catalysis of organic reactions. The most important in organic reactions are metal cations and covalent compounds of metals. Metal cations that play prominent roles as catalysts include the alkali-metal monocations Li+, Na+, K+, Cs+, and Rb+, divalent ions such as Mg +, Ca +, and Zn, marry of the transition-metal cations, and certain lanthanides. The most commonly employed of the covalent compounds include boron trifluoride, aluminum chloride, titanium tetrachloride, and tin tetrachloride. Various other derivatives of boron, aluminum, and titanium also are employed as Lewis acid catalysts. 

The elements that are commonly part of organic compounds are all located in the upper right corner of the periodic table. They are all nonmetals. The bonds between atoms of these elements are essentially covalent. (Some organic molecules may form ions nevertheless, the bonds tvithin each organic ion are covalent. For example, the salt sodium acetate consists of sodium ions, Na+, and acetate ions, C2H,02. Despite the charge, the bonds within the acetate ion are all covalent.)... 

The unstable organic molecules have fixed structures because of the nature of their bonds. The structure of methane is a tetrahedron of covalent single —C — H bonds. Where the structure of even a simple compound is based on double bonds, such as in an ethylene, there are two forms labelled trans and cis geometric isomers ... 

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