Electron configurations relative energies

The electronic configuration of each halogen is one electron less than that of a noble gas, and it is not surprising therefore, that all the halogens can accept electrons to form X" ions. Indeed, the reactions X(g) + e - X (g), are all exothermic and the values (see Table 11.1), though small relative to the ionisation energies, are all larger than the electron affinity of any other atom. 

Information about the structure of a molecule can frequently be obtained from observations of its absorption spectrum. The positions of the absorption bands due to any molecule depend upon its atomic and electronic configuration. To a first approximation, the internal energy E oi a, molecule can be regarded as composed of additive contributions from the electronic motions within the molecule (Et), the vibrational motions of the constituent atoms relative to one another E ), and the rotational motion of the molecule as a whole (Ef) ... 

Uranium is the fourth element of the actinide (SJ series. In the actinide series the electrons are more effectively shielded by the Is and 7p electrons relative to the 4f electrons (shielded by 6s, 6p) in the lanthanide (4p series. Thus, there is a greater spatial extension of 5f orbitals for actinides than 4f orbitals for lanthanides. This results in a small energy difference between and 5/ 6d7s electronic configurations, and a wider range of oxidation states is... 

Solvatochromic shifts are rationalized with the aid of the Franck-Condon principle, which states that during the electronic transition the nuclei are essentially immobile because of their relatively great masses. The solvation shell about the solute molecule minimizes the total energy of the ground state by means of dipole-dipole, dipole-induced dipole, and dispersion forces. Upon transition to the excited state, the solute has a different electronic configuration, yet it is still surrounded by a solvation shell optimized for the ground state. There are two possibilities to consider ... 

The electron configuration or orbital diagram of an atom of an element can be deduced from its position in the periodic table. Beyond that, position in the table can be used to predict (Section 6.8) the relative sizes of atoms and ions (atomic radius, ionic radius) and the relative tendencies of atoms to give up or acquire electrons (ionization energy, electronegativity). 

On the right side of Fig. 3-9 are represented the relative energies of the two Tig terms, the and 2g. The ground term is the from the 2g configuration. Spin-allowed electronic transitions (those between terms of the same spin angular momentum - but see also Sections 3.6, 3.7 and Chapter 4) now take place upon excitation from -> A2g, The d-d spectra of octahedrally... 

FIGURE 5.16 Crystal-field pictures for the low-spin d5 system in deformed octahedra. (a) relative energy of d-orbitals for an octahedron with strong crystal field (b) d-orbitals of the T2s set in a rhombically distorted octahedron (c) three possible electron configurations of increasing total energy (d) the term scheme for the configurations in (c). 

Figure 2 Different electronic configurations arising from the relative strengths of orbital overlap (AE) and pairing energy (PE) AE > PE favours a closed-shell diamagnetic singlet (a) whereas AE

Transition metals tend to have higher melting points than representative metals. Because they are metals, transition elements have relatively low ionization energies. Ions of transition metals often are colored in aqueous solution. Because they are metals and thus readily form cations, they have negative standard reduction potentials. Their compounds often have unpaired electrons because of the diversity of -electron configurations, and thus, they often are paramagnetic. Consequently, the correct answers are (c) and (e). 

The minimum of the triplet state corresponds to a larger Fe-O-O angle (131°) than the S = 1 state (121°), as we also found for a small FeP(Im)(02) system [6b]. On the other hand, an S = 0 closed-shell state is well separated in energy in the linear conformation (22 kcal mol-1 relative to the ground triplet state), but becomes very close to the ground state in the bent conformation (1.4 kcal mob1). Its electronic configuration can be shown schematically as ... 

Main atomic and physical properties of the alkali earth metals are summarized in Tables 5.7 and 5.8. Their typical electron configurations correspond to the outermost ns2 electrons. Alkali earth metals show relatively low 1st and 2nd ionization energies this can be related to the fact that almost without exception both the external 5 electrons take part together in bond formation whether the bond is ionic or covalent. 

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