Orbital copper

These electronic interpretations of valency allow us to interpret the phenomenon of variable valency exhibited by many of the transition metal elements. As shown in Fig. 10.5 (Chapter 10), the transition metals exist because the energy of the outer d orbitals lies between the 5 and p energy levels of the next lowest orbitals, and thus are filled up in preference to the p orbitals. Copper, for example (1 s22s22p63s23p63dl04sl), has a single outer s electron available for bonding, giving rise to Cu(I) compounds, but it can also lose one of the 3d electrons, giving rise to Cu(II) compounds. 

The ions Ga, In, T1, Sn and Pb have the electronic configurations Core (n-l)d ns. The three p-orbitals are therefore vacant and can accept electrons from the filled 7i-orbitals of the arene. Transition elements are also capable of coordination with arenes (p. 204), but here there are important additional interactions involving the metal d-orbitals. Copper(I), silver(I) and gold(I) form... 

Copper belongs to group 11 in the periodic table and the outer electronic configuration is 3d 4s. Since the transition element is defined as an element of which d electrons do not completely fill its d orbital, copper does not simply belong to the transition elements because it has fully filled electrons in the d orbital. However, as copper is usually divalent and its d orbital is not full, copper can therefore be dealt with as a transition element since it shows the properties [8-11]. 

Copper has a FCC structure with one atom m the primitive unit cell. From simple orbital counting, one might... 

The teodeocy to aitaia either a half filled or fully filled set of d orbitals at the expense of the outer s orbital is shown by both chromium and copper and should be noted. This apparent irregularity will be discussed in more detail in Chapter 13. 

Copper differs in its chemistry from the earlier members of the first transition series. The outer electronic configuration contains a completely-filled set of d-orbitals and. as expected, copper forms compounds where it has the oxidation state -)-l. losing the outer (4s) electron and retaining all the 3d electrons. However, like the transition metals preceding it, it also shows the oxidation state +2 oxidation states other than -l-l and - -2 are unimportant. 

Copper(I) oxide [1317-39-1] is 2lp-ty e semiconductor, Cu2 0, in which proper vacancies act as acceptors to create electron holes that conduct within a narrow band in the Cu i7-orbitals. Nickel monoxide [1313-99-17, NiO, forms a deficient semiconductor in which vacancies occur in cation sites similar to those for cuprous oxide. For each cation vacancy two electron holes must be formed, the latter assumed to be associated with regular cations ([Ni " h = Semiconduction results from the transfer of positive charges from cation to cation through the lattice. Conduction of this type is similar... 

The unique nature of the electronic configuration of copper, which contributes to its high electrical and heat conductivity, also provides chemical properties intermediate between transition and 18-sheU elements. Copper can give up the 4s electron to form the copper(I) ion [17493-86-6] or release an additional electron from the >d orbitals to form the copper(Il) ion [15158-11-9]. 

Copper(I) forms compounds with the anions of both strong and weak acids. Many of these compounds are stable and insoluble in water. Compounds and complexes of copper(I) are almost colorless because the inner >d orbital of the copper is completely filled. There is a very strong tendency for copper(I) to disproportionate in aqueous solutions into copper(Il) and metallic copper. 

The properties of copper(Il) are quite different. Ligands that form strong coordinate bonds bind copper(Il) readily to form complexes in which the copper has coordination numbers of 4 or 6, such as tetraammine copper(Tl) [16828-95-8] [Cu(NH3)4], and hexaaquacopper(Il) [14946-74-8] [Cu(H,0),p+ ( see Coordination compounds). Formation of copper(Il) complexes in aqueous solution depends on the abiUty of the ligands to compete with water for coordination sites. Most copper(Il) complexes are colored and paramagnetic as a result of the unpaired electron in the 2d orbital (see Copper... 

Rosetten-baim, /. roset(te) orbit or path, -herd, m. (Copper) refining hearth, -kupfer,... 

As you can see from Figure 6.9, the electron configurations of several elements (marked ) differ slightly from those predicted. In every case, the difference involves a shift of one or, at the most, two electrons from one sublevel to another of very similar energy. For example, in the first transition series, two elements, chromium and copper, have an extra electron in the 3d as compared with the 4s orbital. 

Octet rule The principle that bonded atoms (except H) tend to have a share in eight valence electrons, 166-171 exceptions to, 172-176 molecular geometry and, 181t molecular orbitals and, 650 Octyl acetate, 596t Open-pit copper mine, 540 Oppenheimer, J. Robert, 523 Optical isomer Isomer which rotates the... 

Discuss the conduction of heat by copper (a metal) and by glass (a network solid) in terms of the valence orbital occupancy and electron mobility. 

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