Term symbols from electron configuration

Obtaining Terms Symbols from the Electron Configuration 593... 

The progression of sections leads the reader from the principles of quantum mechanics and several model problems which illustrate these principles and relate to chemical phenomena, through atomic and molecular orbitals, N-electron configurations, states, and term symbols, vibrational and rotational energy levels, photon-induced transitions among various levels, and eventually to computational techniques for treating chemical bonding and reactivity. 

As the electronic energy of an atom or ion will depend on the quantum numbers L, 5, and J, we designate the various energy states which may arise from a given electronic configuration by what is known as a spectro-scopic term symbol ... 

We are now in position to derive the electronic states arising from a given electronic configuration. These states have many names spectroscopic terms (or states), term symbols, and Russell-Saunders terms, in honor of spectroscopists H. N. Russell and F. A. Saunders. Hence, the scheme we use to derive these states is called Russell-Saunders coupling. It is also simply referred to as L-S coupling. 

The symmetric and antisymmetric squares have special prominence in molecular spectroscopy as they give information about some of the simplest open-shell electronic states. A closed-shell configuration has a totally symmetric space function, arising from multiplication of all occupied orbital symmetries, one per electron. The required antisymmetry of the space/spin wavefunction as a whole is satisfied by the exchange-antisymmetric spin function, which returns Fq as the term symbol. In open-shell molecules belonging to a group without... 

Table 9.1 shows the ground-state electron configuration and term symbol for selected elements in the first part of the periodic table. From the term symbol, one can read off the total orbital angular momentum /. aiul ihc total spin angular... 

For homonuclear diatomic molecules, a g or m right subscript is added to the term symbol to show the parity of the electronic states belonging to the term. Terms arising from an electron configuration that has an odd number of electrons in molecular orbitals of odd parity are odd (u) all other terms are even (g). This is the same rule as for atoms. 

Metal ion Colour Ground state electronic configuration Ground state term symbol Magnetic moment. Calculated from equation 25.1 x(298K)//xb Observed... 

Electron Configuration Term Symbol Relative Energy (The Energies of Configurations Differ From Those of d" by a Constant)... 

Because the e and t2 MOs in a tetrahedral LF are inverted from those in an octahedral LF, the correlation diagrams for the electron configurations in a tetrahedral LF are related to those in an octahedral LF as follows correlation diagram. Table 16.22 summarizes the GS term symbols for the different d" electron configurations in both the tetrahedral and octahedral LFs. 

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