Electron groups defined

Each of the steric numbers described in Sections 94 and 94 results in electron groups separated by well-defined bond angles. If the VSEPR model is accurate, the actual bond angles found by experimental measurements on real molecules should match the optimal angles predicted by applying the model. 

The valence electron configuration explains why groups define chemical families that exhibit similar chemical properties. Because it is the valence electrons that determine an element s chemical behavior, and groups have similar valence electron configurations, then elements in the same group display similar chemical behavior. The electron configuration also explains the... 

By this the energy operator for the electronic group describing the properties of the metal ion and its closest surrounding is defined. 

The electron density (10) is the so-called diagonal element of a more general quantity, the (spinless) one-electron density matrix, P(r, r ), defined in exactly the same way except that the variables in it carry primes - which are removed before the integrations. The reduction to (11), in terms of a basis set, remains valid, with a prime added to the variable in the starred function. For a separable wavefunction, the density matrices for the whole system may be expressed in terms of those for the separate electron groups in particular, for a core-valence separation,... 

The shape of a molecule is defined by the locations of its atoms, not its electron groups. 

I Any molecule with one or more lone pairs on the central atom will have a different shape of the electron groups from the shape of the molecule (defined by the locations of the atoms). 

The character table of a point group defines the symmetry properties of a (wave) function as either 1 for symmetric or —1 for antisymmetric with respect to each symmetry operation/ The first row lists all the symmetry operations of the point group and the first column lists the Mulliken symbols of all possible irreducible representations, the symmetry transformation properties that are allowed for wavefunctions. As an example, the character table for the D2h point group is given in Table 4.1. The character tables of all relevant point groups are given in many textbooks.134,273-275 The last column shows the transformation properties of the axes x, y and z, which are used to determine electronic dipole and transition moments (Section 4.5). 

Because all six electron groups have the same ideal bond angle, it makes no difference which position one lone pair occupies. Five bonded atoms and one lone pair define the square pyramidal shape (AX5E), as in iodine pentafluoride (IF5) ... 

---