Tetrahedral geometry VSEPR

The tetrahedral geometry of methane is often explained with the valence shell electron pair repulsion (VSEPR) model The VSEPR model rests on the idea that an electron pair either a bonded pair or an unshared pair associated with a particular atom will be as far away from the atom s other electron pairs as possible Thus a tetrahedral geomehy permits the four bonds of methane to be maximally separated and is charac terized by H—C—H angles of 109 5° a value referred to as the tetrahedral angle... 

Valence shell electron pair repulsion (VSEPR) model (Section 110) Method for predicting the shape of a molecule based on the notion that electron pairs surrounding a central atom repel one another Four electron pairs will arrange them selves in a tetrahedral geometry three will assume a trigo nal planar geometry and two electron pairs will adopt a linear arrangement... 

Tetrahedral geometry may be the most common shape in chemistry, but several other shapes also occur frequently. This section applies the VSEPR model to four additional electron group geometries and their associated molecular shapes. 

Once the Lewis diagram is complete, we can then use the VSEPR method to establish the geometry for the electron pairs on the central atom. The Lewis structure has two bonding electron pairs and two lone pairs of electrons around the central chlorine atom. These four pairs of electrons assume a tetrahedral geometry to minimize electron-electron repulsions. 

Based upon a VSEPR approach, we would predict tetrahedral geometry for each X atom (i.e. Si, P+, S2+) and a bent geometry for each bridging oxygen atom Therefore, a maximum of five atoms in each pyroanion can lie in a plane ... 

The VSEPR model, simple as it is, does a surprisingly good job at predicting molecular shape, despite the fact that it has no obvious relationship to the filling and shapes of atomic orbitals. For example, based on the shapes and orientations of the 2s and 2p orbitals on a carbon atom, it is not obvious why a CH4 molecule should have a tetrahedral geometry. How can we reconcile the notion that covalent bonds are formed from overlap of atomic orbitals with the molecular geometries that come from the VSEPR model ... 

Methane is the simplest hydrocarbon. Physical and chemical studies show that all four C—H bonds are identical in length and strength and the molecule has a tetrahedral geometry with bond angles of 109.5°—consistent with the VSEPR model. How can we explain the tetravalency of carbon within the VB approach In its ground state, the electron configuration of carbon is [He]2/2p. Because the carbon... 

The concept of valence-shell electron-pair repulsion (VSEPR) is presented in introductory organic chemistry as a way to predict molecular geometries. The idea behind VSEPR is that areas of electron density repel each other so that the geometry of bonds and/or lone pairs of electrons around any one atom places these areas as far apart as possible. Por four areas of electron density a tetrahedral geometry is predicted. Eor three areas of electron density a trigonal planar geometry is predicted. Two areas of electron density lead to a linear geometry. 

When carbon forms four single bonds, there are fom electron groups around it, and VSEPR theory (Section 10.7) predicts a tetrahedral geometry. 

For example, to explain the tetrahedral geometry of CH, we say that carbon s 2s and three 2p orbitals blend together, or hybridize, to form four sp hybrid orbitals. (Four atomic orbitals combine to make four hybrid orbitals.) The four sp orbitals, following VSEPR, orient themselves toward the vertices of a regular tetrahedron, hence methane s tetrahedral shape. 

If we do not use hyperconjugation, how are we to describe where the "extra" electrons go This question arises because we seem implicitly to think about bonding in terms of hybridization of atomic orbitals. Thus, in order to describe bonding in the methane molecule consistent with its tetrahedral geometry we introduced the concept of sp hybrid orbitals. That is, the hybridization was introduced because of the geometry. The geometry of a molecule can be determined only experimentally or estimated by using VSEPR theory. 

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