Groups , periodic table trends

The synthesis of the transactinides is noteworthy from a chemical and a nuclear viewpoint. From the chemical point of view, rutherfordium (Z = 104) is important as an example of the first transactinide element. From Figure 15.1, we would expect rutherfordium to behave as a Group 4 (IVB) element, such as hafnium or zirconium, but not like the heavy actinides. Its solution chemistry, as deduced from chromatography experiments, is different from that of the actinides and resembles that of zirconium and hafnium. More recently, detailed gas chromatography has shown important deviations from expected periodic table trends and relativistic quantum chemical calculations. 

In previous arrangements of the Periodic Table see Periodic Table Trends in the Properties of the Elements), the elements beryllium, magnesium, calcium, strontium, barium, and radium were referred to as members of Group Ila, or 2A. As inclusion of the word metaT in their title implies, these elements are both malleable and extrudable however, they are rather brittle. They are electrical conductors. When pure, all except the lightest, beryllium, react with atmospheric... 

Niobium (formerly called columbium) and tantalum are Transition Metals having a considerable affinity for oxygen donor groups they are thus called oxophilic see Oxophilic Character). They occur as mixed-metal oxides such as columbites (Fe/Mn)(Nb/Ta)206 and pyrochlore NaCaNb206p. Their discovery in minerals extends back to the beginning of the nineteenth century, when they were believed to be identical and called tantalum. Rose showed that at least two different elements were involved in the minerals, and named the second one niobium. Their separation was resolved around 1866, especially by Marignac. These metals often display similar chemical behavior as a result of nearly identical atomic radii (1.47 A) due to the lanthanide contraction see Periodic Table Trends in the Properties of the Elements)... 

Platinum (Z = 78) is a whitish, noble metal found in group 10 (or VIIIB) of the periodic table, in the triad with and lying below nickel and palladium (see Periodic Table Trends in the Properties of the Elements). It can be found in elemental form in the mountains of Columbia, where the pre-Columbian natives used it. European chemists discovered and reported it in the mid-1700s. Like gold and silver, it has a positive reduction potential ... 

Galhum (Z = 31) in group 3(A) of the periodic table see Periodic Table Trends in the Properties of the Elements)... 

Antimony (Z = 51) lies between arsenic and bismuth in group 15 (see Periodic Table Trends in the Properties of the Elements). It has been used medicinally since the age of the alchemists. Eike other members of its group it readily forms compounds of the +3 and - -5 states. 

Bismuth (Z = 83) is the heaviest stable element in group 15 (VA) of the periodic table (see Periodic Table Trends in the Properties of the Elements). The Bi isotope, which is 100% abundant, has a 9/2 nuclear spin. Bi, an alpha emitter is used in nuclear medicine as a radiotherapeutic agent. Bismuth has two stable oxidation states Bi(V), corresponding to complete loss of the valence electrons, and Bi(III), a lower oxidation state that retains two valence electrons. Both oxidation states are diamagnetic. The latter is more stable and more common since Bi(V) has a large reduction potential ... 

The concept of an atom s oxidation state see Oxidation Number) can provide fundamental information about the stmcture and reactivity of the compound in which the atom is found. In fact, it can be argued that oxidation states provided the basis for Medeleev s initial organization of the periodic table. For the main group elements, the relative stability of lower oxidation states within a given group increases as the atomic number increases. This trend in the periodic table see Periodic Table Trends in the Properties of the Elements) is generally attributable to the presence of an inert s pair see Inert Pair Effect) caused by relativistic effects see Relativistic Effects). 

General periodic table trends in / for the main-group elements... 

The placement of a new element in the Periodic Table requires knowledge of its atomic number and electronic configuration. Even though the atomic number can be positively assigned by a-decay chains, no knowledge is obtained about the electronic configuration or chemical properties of a new element fi om these physical methods. The elements are just placed in the Periodic Table by atomic number in various groups or series based on simple extrapolation of known Periodic Table trends or firom theoretical calculations and predictions of the electronic structures. It remains to the experimental chemist to attempt to validate or contradict these predictions. 

In any group of the periodic table we have already noted that the number of electrons in the outermost shell is the same for each element and the ionisation energy falls as the group is descended. This immediately predicts two likely properties of the elements in a group (a) their general similarity and (b) the trend towards metallic behaviour as the group is descended. We shall see that these predicted properties are borne out when we study the individual groups. 

By considering the trends in the vertical groups of the Periodic Table, deduce possible answers to the following questions concerning the element astatine (At), atomic number 85. 

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