Cobalt electronic configurations

Symbol Ni atomic number 28 atomic weight 58.693 a transition metal element in the first triad of Group VIll(Group 10) after iron and cobalt electron configuration [Ar]3d 4s2 valence states 0, -i-l, +2, and -f-3 most common oxidation state +2 the standard electrode potential, NF+ -1- 2e Ni -0.237 V atomic radius 1.24A ionic radius (NF+) 0.70A five natural isotopes Ni-58 (68.08%), Ni-60 (26.22%), Ni-61 (1.14%), Ni-62 (3.63%), Ni-64 (0.93%) nineteen radioactive isotopes are known in the mass range 51-57, 59, 63, 65-74 the longest-lived radioisotope Ni-59 has a half-life 7.6x10 years. 

A model similar to that of the iron complex 31 was proposed for the cobalt species synthesized as a result of co-condensation of cobalt vapors with pyrrole in vacuum. A frozen matrix formed is subsequently warmed to room temperature (89JA3881). An oligomer or a polymer results, in which a- and ir-donor functions are realized simultaneously. The model proposed differs from that for the iron pyrrolyl complex by inclusion of the Co—Co bonds to attain the 18-electron configuration. 

By considering electron configurations, suggest a reason why iron(III) is readily prepared from iron(ll) but the conversion of nickel(II) and cobalt(II) into nickel(III) and cobalt(III), respectively, is much more difficult. 

Except for the elements at the ends of the rows, each transition metal can exist in several different oxidation states. The oxidation states displayed by the 3d transition metals are shown in Table 20-1. The most important oxidation states are highlighted in the table. The most common oxidation state for the 3d transition metals is +2, known for all the elements except Sc. Chromium, iron, and cobalt are also stable in the +3 oxidation state, and for vanadium and manganese the -H4 oxidation state is stable. Elements from scandium to manganese have a particularly stable oxidation state corresponding to the loss of ah the valence electrons configuration). 

Samarium (Sm), 74 631t, 634t electronic configuration, 1 41 At Samarium-cobalt magnets, 74 651 Sampatrilat, 5 159... 

In some cases, it would be convenient to condense the electron configuration. In this condensed form, the electronic configuration of the previous noble gas forms a core represented by the atomic symbol of the element enclosed in brackets (i.e., [He] or [Ne]). The electrons added since the noble gas, follow the noble gas core. For example, cobalt can be represented as an argon core plus the 4s and 3d electrons. Thus, ls22s22p63s23p64s23d7 becomes [Ar]4s23d7. 

By sharing the four --electrons of the diene and the six --electrons of the cyclopentadienyl anion, the cobalt(I) atom acquires the electronic configuration of krypton. The formulation of the complex as (XXIV) is supported... 

Indicate the position of iron, cobalt, and nickel in Mendeleev s periodic table of the elements, the electron configurations and sizes of their atoms, and their oxidation states. Explain the observed law of the change in the characteristic oxidation states in the series iron-cobalt-nickel. Why do the elements of the iron family fail to exhibit the highest oxidation state corresponding to the number of the group in the periodic table which they belong to ... 

Now it is very remarkable that cobalt, in ionic compounds, is unstable in the tervalent state, and that the divalent ion has no reducing properties. In a covalent complex ion, cobalt must be in the tervalent state in order to be able to form an 18-electron configuration. By the complex formation, the tervalent state, unusual in ionic compounds, is stabilized. 

A. J. Bearden, W. R. Durnham Iron Electronic Configurations in Proteins Studies by Moss-bauer Spectroscopy. - K Wiitkrich Structural Studies of Hemes and Hemoproteins by Nuclear Magnetic Resonance Spectroscopy. -H. A 0. Hill,A. Roder, R. J. P. Williams The Chemical Nature and Reactivity of Cytochrome P-450. - S. Lindskog Cobalt (II) in Metalloenzymes. A Reporter of Structure-Function Relations. 

Cobalt has an electronic configuration I j 2.v 2/Z 3.v 3pl 3i/74j-. The two 4, electrons arc readily removed producing the ordinary Cu ion. In principle, if the odd 3complex ions or crystal lattices in which cases additional electron orhitals are tilled. 

With its 3d84,r2 electron configuration, nickel forms Ni2 ions. Having a nearly complete 3d subshell, nickel does not yield a 3d electron as readily as iron and cobalt, and trivalent and tetravalent forms are known only in the hydrated oxides. Ni203 and Ni()2. and a few complexes. 

Ferrocene is only one of a large number of compounds of transition metals with the cyclopentadienyl anion. Other metals that form sandwich-type structures similar to ferrocene include nickel, titanium, cobalt, ruthenium, zirconium, and osmium. The stability of metallocenes varies greatly with the metal and its oxidation state ferrocene, ruthenocene, and osmocene are particularly stable because in each the metal achieves the electronic configuration of an inert gas. Almost the ultimate in resistance to oxidative attack is reached in (C5H5)2Co , cobalticinium ion, which can be recovered from boiling aqua regia (a mixture of concentrated nitric and hydrochloric acids named for its ability to dissolve platinum and gold). In cobalticinium ion, the metal has the 18 outer-shell electrons characteristic of krypton. 

Fig. 5.29. Electron configurations for low spin cobalt(II). The first excited state is often high in energy, and thus the electron relaxation times are at least one order of magnitude longer than in high spin cobalt(II).

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