This simple model is based on the fact that electrons repel each other, and that it is reasonable to expect that the bonds and non-bonding valence electron pairs associated with a given atom will prefer to be as far apart as possible. īonding configurations are readily predicted by valence-shell electron-pair repulsion theory, commonly referred to as VSEPR in most introductory chemistry texts. The following examples make use of this notation, and also illustrate the importance of including non-bonding valence shell electron pairs (colored blue) when viewing such configurations. a covalent bond that is partially formed or partially broken). Some texts and other sources may use a dashed bond in the same manner as we have defined the hatched bond, but this can be confusing because the dashed bond is often used to represent a partial bond (i.e. A wedge shaped bond is directed in front of this plane (thick end toward the viewer), as shown by the bond to substituent B and a hatched bond is directed in back of the plane (away from the viewer), as shown by the bond to substituent D. The two bonds to substituents A in the structure on the left are of this kind. As defined in the diagram on the right, a simple straight line represents a bond lying approximately in the surface plane. In most cases the focus of configuration is a carbon atom so the lines specifying bond directions will originate there. In order to represent such configurations on a two-dimensional surface (paper, blackboard or screen), we often use perspective drawings in which the direction of a bond is specified by the line connecting the bonded atoms. This shape is dependent on the preferred spatial orientation of covalent bonds to atoms having two or more bonding partners.Three dimensional configurations are best viewed with the aid of models. The three dimensional shape or configuration of a molecule is an important characteristic.
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