Lithium, electron configuration

Lithium chemistry Lithium is an alkali metal, electronic configuration ls 2s forming a... 

The alkali metals form a homogeneous group of extremely reactive elements which illustrate well the similarities and trends to be expected from the periodic classification, as discussed in Chapter 2. Their physical and chemical properties are readily interpreted in terms of their simple electronic configuration, ns, and for this reason they have been extensively studied by the full range of experimental and theoretical techniques. Compounds of sodium and potassium have been known from ancient times and both elements are essential for animal life. They are also major items of trade, commerce and chemical industry. Lithium was first recognized as a separate element at the beginning of the nineteenth eentury but did not assume major industrial importance until about 40 y ago. Rubidium and caesium are of considerable academic interest but so far have few industrial applications. Francium, the elusive element 87, has only fleeting existence in nature due to its very short radioactive half-life, and this delayed its discovery until 1939. 

From Figure 6.8 it is possible to predict the electron configurations of atoms of elements with atomic numbers 1 through 36. Because an s sublevel can hold only two electrons, the Is is filled at helium (Is2). With lithium (Z = 3), the third electron has to enter a new sublevel This is the 2s, the lowest sublevel of the second principal energy level. Lithium has one electron in this sublevel (ls s1)- With beryllium (Z = 4), the 2s sublevel is filled (ls22s2). The next six elements fill the 2p sublevel. Their electron configurations are... 

The situation in beryllium metal is more complex. We might expect all of the 2s molecular orbitals to be filled because beryllium has the electron configuration ls22s2. However, in a crystal of beryllium, the 2p MO band overlaps the 2s (Figure 5). This means that, once again, there are vacant MOs that differ only infinitesimally in energy from filled MOs below them. This is indeed the basic requirement for electron conductivity it is characteristic of all metals, including lithium and beryllium. 

The electron configuration for lithium is ls 2s1 and for beryllium it is ls 2s. Estimate the approximate ionization energies to remove first one, then a second, electron. Explain your estimates. 

A lithium atom has three electrons. The first two electrons fill lithium s lowest possible energy level, the 1. S orbital, and the third electron occupies the 2 5 orbital. The three representations for the ground-state electron configuration... 

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... 

Ans. Onlv hvdrogen. Lithium and beryllium arc metals, which tend to lose electrons (and form ionic bonds) rather than share. The resulting configuration of two electrons in the first shell, with no other shells occupied, is stable, and therefore is also said to satisfy the octet rule. Second-period elements of higher atomic number tend to acquire the electron configuration of neon. If the outermost shell of an atom is the first shell, the maximum number of electrons in the atom is 2. 

This energy is not likely to be repaid during compound formation. The reason for such a high second ionization energy for lithium is because the electron configuration of Li+ is Is2 which has a filled s orbital. It is the special stability of the filled s orbital which prevents the formation of Li2+ ions. Also, the formation of Li2+ requires 14 times more energy than the formation of Li+ and so is much less likely. 

For example, lithium has three electrons, two in the ls-orbital and one in the 2s orbital. Its electron configuration would be 1 s22s1... 

For a few elements following lithium, the electron configurations corresponding to the progressive attribution of electrons to the different orbitals according to the energy increase are ... 

Refer to the sets of quantum numbers for hydrogen and helium that you saw earlier. Then use the quantum numbers for lithium to infer why a lithium atom has the ground state electron configuration that it does. 

The same principles that are valid for the surface of crystalline substances hold for the surface of amorphous solids. Crystals can be of the purely ionic type, e.g., NaF, or of the purely covalent type, e.g., diamond. Most substances, however, are somewhere in between these extremes [even in lithium fluoride, a slight tendency towards bond formation between cations and anions has been shown by precise determinations of the electron density distribution (/)]. Mostly, amorphous solids are found with predominantly covalent bonds. As with liquids, there is usually some close-range ordering of the atoms similar to the ordering in the corresponding crystalline structures. Obviously, this is caused by the tendency of the atoms to retain their normal electron configuration, such as the sp hybridization of silicon in silica. Here, too, transitions from crystalline to amorphous do occur. The microcrystalline forms of carbon which are structurally descended from graphite are an example. 

For example, lithium has an electron arrangement 2,1, but its electronic configuration is Is 2s. The characters in red indicate the shell and subshell. The numbers in blue indicate the number of electrons in that subshell. So the two electrons in the first shell of lithium atoms are located in the Is subshell or Is orbital. The one electron in lithium s second shell is in the 2s subshell or 2s orbital. Now consider carbon. It has the electron arrangement 2, 4. The two electrons in the first shell go into the Is orbital. The next subshell to be filled is the 2s orbital, which holds a maximum of two electrons. The remaining two electrons go into the next available subshell, which is 2p. So carbon has an electronic configuration Is 2s 2pl... 

The normal lithium atom has two electrons in the K shell, with n = 1, and one electron in the 2s orbital of the L shell. The electronic configurations of all of the alkali atoms are given in Table 2-1 in each case there is a single electron in the outermost shell. 

Lithium and beryllium. Two lithium atoms contain six electrons. Pour will fill the als and tr s orbitals with no bonding. The last two electrons will enter the os, orbital, giving a net bond order of one in the Lk molecule. The electron configuration will be... 

---