Electron configurations bromide anion

Bromine, a halogen, has seven valence electrons, so it gains one to complete its octet (eight valence electrons) and form the bromide anion with a 1-charge. The electron configuration for the bromide anion is... 

The fact that the scandium(III) ion has the 3d electronic configuration severely limits the kinds of physical methods that can be brought to bear on determining the nature of the chemical environment in its complexes. The Sc nuclide has 100% natural abundance and a high sensitivity compared to protons and NMR studies using Sc may well prove to be a powerful tool (Melson et al., 1974). NMR spectra of aqueous solutions of scandium(III) chloride, perchlorate, nitrate, and sulfate have been obtained and it has been demonstrated that the chemical shifts for Sc at very low concentrations for the chloride, bromide, and perchlorate are independent of the anion and may be characteristic of the [Sc(OH)] ion. At higher concentrations the chemical shifts are both anion- and concentration-dependent and reflect the formation of bromo and chloro complexes and in the case of the perchlorate, polymeric hydroxo species. The chemical shifts for the nitrate and sulfate are different from the others and indicate that even at low concentrations there must be significant quantities of the respective complexes. 

More extensive investigations have revealed additional complexities in the SET mechanism. Thus, evidence supportive of both free radical and radical anion (SrnI) chain processes has been observed in reactions of alkyl iodides, both pathways presumably being initiated by electron transfer between cuprate and substrate. Although incapable of sustaining free radical chain processes, alkyl bromides do apparently react, at least in part, by an SrnI mechanism. While the intervention of free radical processes in reactions of alkyl bromides would appear to be inconsistent with the predominant stereochemical inversion exhibited by these substrates, Ashby has demonstrated that electron transfer processes can occur with inversion of configuration. 

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