Thallium, electronic configuration

Group 13/III is the first group of the p block. Its members have an ns np1 electron configuration (Table 14.5), and so we expect a maximum oxidation number of +3. The oxidation numbers of B and A1 are +3 in almost all their compounds. However, the heavier elements in the group are more likely to keep their s-electrons (the inert-pair effect, Section 1.19) so the oxidation number +1 becomes increasingly important down the group, and thallium(I) compounds are as common as... 

The smaller ionic radius for Tl produces the more negative enthalpy of hydration. The two ions have similar outer electronic configurations L.a has the [Xc] structure and Tl is [Xe]4l14 Thallium experiences the inert-pair ellect. itself a consequence oft he large values for the second and third ionization enemies. 

The valence electron configuration of the group 3A elements is ns2 npl, and their primary oxidation state is +3. In addition, the heavier elements exhibit a +1 state, which is uncommon for gallium and indium but is the most stable oxidation state for thallium. 

There is also a pronounced tendency for the Group IIIA metals to form metal-metal bonds and bridged structures. The electron configuration ns2 np1 suggests the possible loss of one electron from the valence shell to leave the ns2 pair intact. The electron pair that remains in the valence shell is sometimes referred to as an inert pair, and a stable oxidation state that is less than the group number by two units is known as an inert pair effect. The fact that oxidation states of +2, +3, +4, and +5 occur for the elements in Groups IVA, VA, VIA, VIIA, respectively, shows that the effect is quite common. Thus, it will be seen that the Group IIIA metals other than aluminum have a tendency to form +1 compounds, especially thallium. 

Write the electronic configuration for thallium (element 81), using the shortened notation. 

The metallic element thallium, atomic number 81 (relative atomic mass 204.38), is the heaviest member of group 13 of the periodic table. The ground-state electron configuration is [XeJdf Sd Obs bp. ... 

There are some important exceptions to the rules discussed here. For example, tin forms both Sn2+ and Sn4+ ions, and lead forms both Pb2+ and Pb4+ ions. Also, bismuth forms Bi3+ and Bi5+ ions, and thallium forms Tl+ and Tl3+ ions. There are no simple explanations for the behavior of these ions. For now, just note them as exceptions to the very useful rule that ions generally adopt noble gas electron configurations in ionic compounds. Our discussion here refers to representative metals. The transition metals exhibit more complicated behavior, forming a variety of ions that will be considered in Chapter 20. 

Thallium has the electronic configuration of [Xe]4/ " 5if 6i 6/), and forms compounds in the oxidation states I, II, and III. Thallium(II) derivatives are relatively rare. In general the bonding between T1(III) and a donor is more covalent in nature, whereas T1(I) compounds show more ionic behavior. Interactions between the T1(I) atoms of neighboring molecules are common. The theoretical explanation has been controversial." The coordination chemistry of T1(III) is complicated by the highly oxidizing power of thallium(III) in both aqueous and nonaqueous solutions. 

The monovalent thallium ion, with its relatively large ionic radius (1.50 A for a 6-coordinate ion), has only weak electrostatic interactions with its ligands. The valence-shell electronic configuration of d s with a lone pair makes the covalent interactions weak as well. Overall, the thallium ion is weakly solvated in most solvents, and crystallizes even without any coordinated solvent molecules. Thallium(I) compounds are the most widely explored group among thallium derivatives. The T1+ state is also the most stable ion in aqueous solutions. 

The elements aluminum, gallium, indium and thallium have valence electron configurations (ns)... 

The dominant oxidation states for thallium are the mono and trivalent states. The thallous ion (TU) is colorless has a radius of 1.4 A, and usually exists as a six- or eight-coordinate structure in crystalline salts [1,2]. The thallous ion can produce a base that is weaker than KOH (i.e., TlOH). Thallium can also be considered a soft Lewis acid its softness is attributed to its d ° electron configuration. A variety of water-soluble thallous salts exist including the cyanide, nitrate, carbonate, sulfate, and phosphate. Insoluble salts such as the chloride (TlCl) or the sulfide (TljS) also exist. 

The regular filling of the 6p orbitals accounts for the outer electronic configurations of the elements from thallium to radon, thus completing the third long period with its integral f-block elements. 

The primary selection rule for allowed Ml transitions is that the electron configuration not change. Since we are only interested in those configurations that have valence electrons with finite probability of being at the nucleus, we are limited to p electrons there is always one configuration for purely s valence electrons. The stable elements with the largest enhancement that also have p valence electronic configurations are thallium... 

Write the full electronic configurations of the following elements a) phosphorus, J ) copper, (c) arsenic, and (ct) thallium. 

So now let s consider a specific example from Group 3A, namely, thallium. Its electron configuration is Xe 4f St °6s 6p. The fact that the filled and Sdorbitals are positioned between the two 6s electrons and the nucleus is at the heart of the reason that we say that the fiUed 4f Sd subshells shield the 6s electrons from... 

Thallium is in group 13 and period 6. Its valence-shell electron configuration is 6s 6p. Again, we indicate the electron configuration of the noble gas that closes the fifth period as a core, and add the subshells that fill in the sixth period 6s, 4/, 5d, and 6p. 

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