Copper electronic configurations

Apparent anomalies in the filling of electron orbitals in atoms occur in chromium and copper. In these elements an electron expected to fill an s-orbital fills the d-orbitals instead, (a) Explain why these anomalies occurs, (b) Similar anomalies are known to occur in seven other elements. Using Appendix 2C, identify those elements and indicate for which ones the explanation used to rationalize the chromium and copper electron configurations is valid, (c) Explain why there are no elements in which electrons fill ( / + I )s-orbitals instead of np-orbitals. 

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. 

Spectroscopic. The electronic configuration of Pu vapor is [Xe] The earliest studies of copper- and silver-spark spectra... 

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 is the first member of Group IB of the periodic table, having atomic number 29 and electronic configuration 2.8.18.1. Loss of the outermost electron gives the cuprous ion Cu, and a second electron may be lost in the formation of the cupric ion Cu. ... 

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. 

Perhaps the most obvious metallic property is reflectivity or luster. With few exceptions (gold, copper, bismuth, manganese) all metals have a silvery white color which results from reflecting all frequencies of light. We have said previously that the electron configuration of a substance determines the way in which it interacts with light. Apparently the characteristic reflectivity of metals indicates that all metals have a special type of electron configuration in common. 

In any case, as many authors have previously pointed out the n + rule is strictly speaking subject to about 20 exceptions, thus further hinting that it has no fundamental value.11 The best known of these anomalies occur in the neutral atoms of chromium and copper which have the following expected and observed electronic configurations, which generations of general chemistry student have been obliged to learn ... 

By considering electron configurations, explain why gold and silver are less reactive than copper. 

The 2 1 species are known as cuprates and are the most common synthetic reagents. Disubstituted Cu(I) species have the 3c 10 electronic configuration and would be expected to have linear geometry. The Cu is a center of high electron density and nucleophilicity, and in solution, lithium dimethylcuprate exists as a dimer [LiCu(CH3)2]2.3 The compound is often represented as four methyl groups attached to a tetrahedral cluster of lithium and copper atoms. However, in the presence of Lil, the compound seems to be a monomer of composition (CH3)2CuLi.4... 

There are a few exceptions to this general pattern. The two best-known exceptions are the elements chromium, Cr, and copper, Cu. The electron configurations for these two elements are ... 

Unfortunately, there is little electrochemical information on these complexes. The only study available is concerned with [Cu(bipy)3]2+ and [Cu(phen)3]2+, which, in agreement with the d9 electronic configuration, have a magnetic moment of about 1.8 jUB-188 The two complexes, in MeCN solution, display a Cu(II)/Cu(I) reduction at E01 — +0.04 and + 0.03 V (vs. SCE), respectively, which is complicated by decomposition of the electrogenerated copper(I) complexes.189... 

The chart below shows electron configurations and partial orbital diagrams for the 18 elements of period 4. You would expect the filling pattern shown for potassium (Z = 19) through vanadium (Z = 23). However, an unexpected deviation from the pattern occurs with chromium (Z = 24). The same thing happens with copper (Z = 29). All other configurations for period 4 conform to the aufbau principle. 

As a consequence of its electronic configuration, a variety of coordination numbers and geometries have been observed for copper(I) compounds, especially for inorganic representatives (see Fig. 1.3) [32]. In the organometallic chemistry of copper, the linear and trigonal coordination geometries in particular, though distorted towards T-shaped, are frequently encountered. 

The electron arrangements in the SQA Data Booklet and the electronic configurations written in spectroscopic notation in the table show that chromium and copper are out of step with the aufbau principle. However, there is a special stability associated with half-filled or completely filled d orbitals. Bear this in mind when looking at the orbital box notation and you can understand why chromium is [Ar] 3d 4s and copper is [Ar] 3d 4s, rather than the [Ar] 3d 4s and [Ar] dd" 4s as you might have expected. 

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