Atoms single central

This principle can be restated in a somewhat different way for molecules in which there is a single central atom. The geometry of such a molecule depends only on—... 

The VSEPR model applies equally well to molecules in which there is no single central atom. Consider the acetylene molecule, C2H2. Recall that here the two carbon atoms are joined by a triple bond ... 

A species consisting of several ligands (the Lewis bases) that have an independent existence bonded to a single central metal atom or ion (the Lewis acid). Examples (1) H,N—BF, (2) [Fe(H2())J,l PtCl4. composite material A synthetic material composed of a polymer and one or more other substances that have been solidified together. 

The concentrates were subsequently analysed for arsenic using Varian-Techtron AAS atomic absorption spectrophotometer fitted with a Perkin-Elmer HGA 72 carbon furnace, linked to a zinc reductor column for the generation of arsine (Fig. 5.3). A continuous stream of argon was allowed to flow with the column connected into the inert gas line between the HGA 72 control unit and the inlet to the furnace. Calcium sulfate (10-20 mesh) was used as an adsorbent to prevent water vapour entering the carbon furnace. The carbon tube was of 10 mm id and had a single centrally located inlet hole. 

Draw Lewis structures for the following molecules. (Note Neither of these molecules has a single central atom.)... 

Oxygen acids that do not contain a single central atom have strengths corresponding to reasonable extensions of the rules, as shown by the following examples ... 

Glyceraldehyde has a single asymmetric carbon atom (the central one) and so two stereoisomers (also called optical isomers) are possible, that is two forms of glyceraldehyde, denoted as d- and L-glyceraldehyde, which are mirror images of each other (Fig. 2). Stereoisomers also exist for amino acids (see Topic Bl). 

Conjugation of Several Phenyl Radicals Bonded to a Single Central Atom. J. chem. Physics 22, 1430—1433 (1954). 

Up to now we have dealt with molecules in which the orbitals on a single central atom are considered to be hybridized. Let us now see how these various models of hybridization can help us understand bonding between pairs of such atoms. Because of its... 

The main difficulty with the valence-bond approach is that the atomic orbitals, whether hybridized or not, result from the interaction of electrons with a single central force field— that of the atomic nucleus. An electron that spends most of its time between two nuclei will find itself in a very different, two-center force field, and this will give rise to new types of orbitals that are better characterized as molecular, rather than as atomic orbitals. 

Atom-Centered Fragments (ACE) consist of a single central atom surrounded by one or several shells of atoms separated from the central one by the same topological distance. This type of structural fragments was introduced in the early 1950s by Tatevskii, " and then by Benson to predict some physicochemical properties of organic compounds in the framework of additive schemes. 

---