Argon valence

The electronic structure of the chlorine atom (3s-3p ) provides a satisfactory explanation of the elemental form of this substance also. The single half-filled 3p orbital can be used to form one covalent bond, and therefore chlorine exists as a diatomic molecule. Finally, in the argon atom all valence orbitals of low energy are occupied by electrons, and the possibility for chemical bonding between the atoms is lost. 

For example, nitrogen ( N ) has five valence electrons and needs three more electrons to complete its octet. Chlorine (-CL) has seven valence electrons and needs one more electron to complete its octet. Argon OArO already has a complete octet and has no tendency to share any more electrons. Hydrogen (H-) needs one more electron to reach its helium-like duplet. Because hydrogen completes its duplet by sharing one pair of electrons, we say that it has a valence of 1 in all its compounds. In general, the valence of an element is the number of bonds that its atoms can form. 

Chlorine would have to lose seven electrons to reach an electron configuration like that of neon. But if it gained one, it would have the same stable electron configuration as argon. So that is what chlorine does. If it meets an atom with a high-energy valence electron, such as sodium, the electron migrates to the chlorine atom and forms a chloride ion ... 

Its formation can be observed after short irradiation with a wavelength of A. = 313 nm in argon at 10 K. It is possible to use the comparison of the experimental IR spectrum with the calculated spectra for the singlet and triplet carbene to determine the singlet multiplicity of the isolated molecule. Its structure cannot easily be described by normal valence formulas. The calculated... 

Sodium loses its valence electron and its electron configuration becomes identical to that of neon Is2 2s2 2p6. Likewise, the valence shell of chlorine becomes completely filled and its electron configuration resembles that of argon. As a result, during the reaction... 

Neon has eight valence electrons and all of them are paired, hence the valence orbitals of neon are completely filled. Therefore neon is very unreactive and does not bond with any other element. Similarly, the group 8A elements (noble gases) helium and argon are very unreactive. However, krypton and xenon may form bonds under certain conditions. 

The charges on the chlorine, potassium, and calcium ions result from a strong tendency of valence electrons to adopt the stable configuration of the inert gases, with completely filled electronic shells. Notice that the 3 ions have electronic configurations identical to that of inert argon. 

By contrast, the nonmetallic elements on the right side of the periodic table have many valence electrons and can most readily attain the stable configuration of the inert gases by gaining electrons. Table 5-3 compares three nonmetals to the inert gas argon. 

The average local electrostatic potential V(r)/p(r), introduced by Pohtzer [57], led Sen and coworkers [58] to conjecture that the global maximum in V(r)/p(r) defines the location of the core-valence separation in ground-state atoms. Using this criterion, one finds N values [Eq. (3.1)] of 2.065 and 2.112 e for carbon and neon, respectively, and 10.073 e for argon, which are reasonable estimates in light of what we know about the electronic shell structure. Politzer [57] also made the significant observation that V(r)/p(r) has a maximum any time the radial distribution function D(r) = Avr pir) is found to have a minimum. 

Fig. 27. Valence band spectra of oxidized Pu metal and sintered PUO2 for Hell excitation (40.8 eV), curve I Pu metal -I- PU2O3 curve 2 PU2O3 curve 3 PU2O3 -I- PUO2 curve 4 PUO2 (all for oxidized Pu metal) curve 5 sintered PuOj (Argon sputtered)...

The pseudo-potentials used here are of the 1-dependent semi-local type, according to the expression of Barthelat and Durand The single valence electron pseudo-potential for the [Na ] core has been widely used in accurate standard valence calculations The argon atoms are represented via [Ar]... 

The sum in W runs over all polarizable cores (k=Na, Ar) a% is the dipole polarizability of core X, namely 0.9947 ao and 11.08 ao for sodium and argon respectively fx is the electrostatic field at center X, produced by the ion [Na ] and the single valence electron at relative distance r of core k. The electronic field is truncated by a stepwise cut-off function Fx, in order to avoid integral divergencies ... 

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