Configuration ground

Table 7.1 Ground configurations and ground states of atoms, listed in increasing order of atomic number Z, and their first ionization energies, E...

It follows from this that the excited configurations of C and Si in Equation (7.10) give P, P, D, D, and terms. It follows also that the noble gases, in which all occupied orbitals are filled, have only 5 terms arising from their ground configurations. 

Using these rules it follows that, for the ground configurations of both C and O in Equation (7.17), the term is the lowest in energy. 

Atoms wifh a ground configuration in which an orbifal is exacfly half-filled, as for example in N(2/> ), Mn(3ti ) and Eu(4/ ), always have an S ground sfafe. Since such sfafes have only one componenf fhe problem of a normal or inverted mulfiplef does nof arise. Table 7.1 gives fhe ground sfafes of all atoms in fhe periodic fable. 

For hydrogen and the alkali metal atoms in their ground configurations, or excited configurations involving promotion of the valence electron, there is only one electron with an unpaired spin. For this electron = - - or — and the corresponding electron spin part... 

For the ground configuration, fx, the orbital wave function is given by... 

MOs around them - rather as we construct atomic orbitals (AOs) around a single bare nucleus. Electrons are then fed into the MOs in pairs (with the electron spin quantum number = 5) in order of increasing energy using the aufbau principle, just as for atoms (Section 7.1.1), to give the ground configuration of the molecule. 

Some heteronuclear diatomic molecules, such as nitric oxide (NO), carbon monoxide (CO) and the short-lived CN molecule, contain atoms which are sufficiently similar that the MOs resemble quite closely those of homonuclear diatomics. In nitric oxide the 15 electrons can be fed into MOs, in the order relevant to O2 and F2, to give the ground configuration... 

ELECTRONIC SPECTROSCOPY OF DIATOMIC MOLECULES The ground configuration of oxygen is... 

So, the states that arise from the ground configuration of oxygen are 2g, Ig and Ag. One of Hund s mles (the first on page 212) tells us thsAX I g is the ground state. The Pauli principle forbids the Eg, Ig and Ag states. 

Table 7.5 States from ground configurations in diatomic molecules...

The ground configuration of benzene is obtained by feeding the six electrons, which were originally in 2p AOs on the carbon atoms (z axis perpendicular to the ring), into the lower energy MOs giving... 

From the discussion in Section 7.1.2.3 we can deduce that the state arising from the ground configuration of Ar is However, the ground configuration of Ar gives rise to two states, Pi/2 since L= and S = j, giving a term, and J = or. These two states of... 

In Section 7.3.1.3 the 71-electron MOs of benzene were obtained by the Hiickel method using only the Ip AOs on the six carbon atoms. The ground configuration is... 

The ground configuration of Ne is ls 2s 2p, giving a sfafe. The excifed configurations give rise fo sfafes fo which fhe Russell-Saunders approximation does nof apply. Nevertheless, any. .. 2p ns or. .. 2p np configuration, wifh n > 2, gives rise fo four or fen sfafes, respectively, as would be fhe case in fhe Russell-Saunders approximation (see... 

The ground configuration of Ar is KL3s 3p, giving an inverted P /2 multiplet. The excited states involved in laser action involve promotion of an electron from the 3p orbital into excited As,5s,Ap,5p,3d,Ad,... orbitals. Similarly, excited states of Kr involved arise from promotion of an electron from the Ap orbital. In Ar the KL3s 3p configuration gives rise to 5, V, terms (see Section 7.1.2.3). Most laser transitions involve the core in one of the states and the promoted electron in the Ap orbital. 

What is of primary importance chemically is not the ground state, nor the ground configuration, which is some average of valence states, of the free atom but it is the atomic response properties to perturbations by other atoms. That is governed by the energies and spatial extensions and polarizabilities of the upper core and of the compact valence orbitals ([34], p 653). 

First, consider an octahedral nickel(ii) complex. The strong-field ground configuration is 2g g- The repulsive interaction between the filled 2g subshell and the six octahedrally disposed bonds is cubically isotropic. That is to say, interactions between the t2g electrons and the bonding electrons are the same with respect to x, y and z directions. The same is true of the interactions between the six ligands and the exactly half-full gg subset. So, while the d electrons in octahedrally coordinated nickel(ii) complexes will repel all bonding electrons, no differentiation between bonds is to be expected. Octahedral d coordination, per se, is stable in this regard. 

Molecules have some occupied and some unoccupied orbitals. There occur diverse interactions (Scheme 1) when molecules undergo reactions. According to the frontier orbital theory (Sect 3 in Chapter Elements of a Chemical Orbital Theory by Inagaki in this volume), the HOMO d) of an electron donor (D) and the LUMO (fl ) of an electron acceptor (A) play a predominant role in the chemical reactions (delocalization band in Scheme 2). The electron configuration D A where one electron transfers from dio a significantly mixes into the ground configuration DA where... 

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