Atomic state term symbols

Atomic States, Term Symbols, and Hand s Rule... 

To keep track of the different angular momenta in atomic states, term symbols are used to specify the values of /, m, and j ... 

To illustrate this point, consider how the state of Carbon would be expected to interact with an approaching Ne atom. This term symbol s wavefunction = 3"k2 [ IpoapoPI - Ip-iapipl... 

The term symbol summarizes the properties of any state and also permits a concise representation of spectral transitions. It consists of an upper case letter (S, P, D. ..) to represent the net orbital angular momentum (L) and a number written as a superscript on the upper left to indicate spin multiplicity (i. e. the number of possible orientations of total spin of the atom). L is zero for Fe " (no angular momentum) and 2 for Fe ". The spin multiplicity is defined as (2S -i- 1) S = 5/2 and 2 for Fe " and Fe ", respectively. The ground state term symbol for Fe " is, therefore, 85 2 and for Fe " it is 04. The subscript on the right is the value J. 

For multielectron atoms, the term symbol for an energy state is represented as... 

Determine the term symbols for the N atom. Show all work, (a) Determine the number of possible microstates, (b) Write out all the possible combinations of the electrons in a microstates table, (c) Extract the term symbols and determine the degeneracy of each term, (d) Determine the ground-state term symbol using Hund s rule of maximum multiplicity. 

In the same way that filled atomic subshells contributed nothing to the angular momentum of the atom s term symbol, the angular momenta cancel among the electrons in a fully occupied set of degenerate MOs. Electronic 2 states in which the TT, 8, and other A 7 0 MOs are all filled are always 2 states. 

Predict the ground state term symbol for each of the following atoms. 

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. 

The first excited state of the molecule, c N , is built from normal atoms, and has the term symbol 2n. It lies 1.78 v. e. above the normal state. 

In a manner similar to that by which the atomic states were designated as s, p, d, or /, the letters S, P, D, and F correspond to the values of 0, 1, 2, and 3, respectively, for the angular momentum vector, L. After the values of the vectors L, S, and / have been determined, the overall angular momentum is described by a symbol known as a term symbol or spectroscopic state. This symbol is constructed as Ps+1)Lj where the appropriate letter is used for the L value as listed earlier, and the quantity (2S + 1) is known as the multiplicity. For one unpaired electron, (2S + 1) = 2, and a multiplicity of 2 gives rise to a doublet. For two unpaired electrons, the multiplicity is 3, and the state is called a triplet state. 

As in the case of atoms, the molecular term symbol is written as 2S+1L, where L is the absolute value of Ml (the highest positive value). The molecular states are designated as for atoms except for the use of capital Greek letters ... 

In an atomic term symbol the value of L = 1,2,..., etc. is coded according to spectroscopic notation as 5, P, D,F,G,... etc. (alphabetically for L > 3). Likewise, each atomic state can be characterized by a total electronic spin quantum number S,... 

A. 12-1. Spectroscopic states end term symbols for meny-electron atoms or ions... 

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 ... 

The Pauli exclusion principle forbids cotain combinations of nt, and m, in determining the term symbols for the states of the nitrogen atom. Consider an excited nitrogen atom in which the electronic configuration is ls22522p13pI. What states now are possible ... 

Determine all of the term symbols for the following free atoms. Choose the ground state term in each case. 

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