Explain the following trend in electron affinities: Al (−41.8 kJ/mol), Si (−134.1 kJ/mol), P (−72.0 kJ/mol), and S (−200.4 kJ/mol).How would this phenomenon explain why Sn 2 + is a better reducing agent than Pb 2 +? Give two reasons for the inert-pair effect. Based on the position of beryllium in the periodic table, identify the second element. Two elements are effective additives to solid rocket propellant: beryllium and one other element that has similar chemistry.Although many of the properties of the second- and third-period elements in a group are quite different, one property is similar.What is the diagonal effect? How does it explain the similarity in chemistry between, for example, boron and silicon?.Give a reasonable explanation for this tendency. The heavier main group elements tend to form extended sigma-bonded structures rather than multiple bonds to other atoms.the solubility of the halides in nonpolar solvents.Compare the second-period elements and their heavier congeners with regard to.Give three reasons the chemistry of the second-period elements is generally not representative of their groups as a whole.Arrange As, O, Ca, Sn, Be, and Sb in order of decreasing metallic character.Of Ca, Br, Li, N, Zr, Ar, Sr, and S, which elements have a greater tendency to form positive ions than negative ions?.Compare the properties of the metals and nonmetals with regard to their electronegativities and preferred oxidation states.Which periodic trends are affected by Z eff? Based on the positions of the elements in the periodic table, which element would you expect to have the highest Z eff? the lowest Z eff?.decreasing magnitude of electron affinity.Arrange Rb, H, Be, Na, Cs, and Ca in order of.Arrange K, Cs, Sr, Ca, Ba, and Li in order of.List three physical properties that are important in describing the behavior of the main group elements.Therefore the distinguishing electron must occupy either the 5 s or 5 p subshell.\) For example, iodine is a representative element in the fifth period. The value of n, the principal quantum number for the distinguishing electron, can be quickly determined by counting down from the top of the periodic table. As a general rule, in the case of the representative elements, the distinguishing electron will be in an ns or np subshell. In the third period the 3 s subshell is filling for Na and Mg, and therefore Al, Si, P, S, Cl, and Ar. Across the second period Li and Be have distinguishing electrons in the 2 s subshell, and electrons are being added to the 2 p subshell in the atoms from B to Ne. In the first period the distinguishing electrons for H and He are in the 1 s subshell. The first three horizontal rows or periods in the modern periodic table consist entirely of representative elements. Formulas for chlorides of the first dozen elements that show the periodic variation of valence Element This agrees with the valence rules derived from the periodic table, and results in formulas for chlorides of the first dozen elements that show the periodic variation of valence. For representative elements the number of valence electrons is the same as the periodic group number, and the number needed to match the next noble-gas configuration is 8 minus the group number. That is, the valences of the representative elements may be predicted on the basis of the number of valence electrons they have, or from the number of electrons that would have to be added in order to attain the same electron configuration as an atom of a noble gas. Many of the chemical properties of the representative elements can be explained on the basis of Lewis diagrams. Most of the elements whose chemistry and valence we have discussed so far fall into this category. The representative elements are those in which the distinguishing electron enter an s or p subshell. The type of subshell ( s, p, d, f)into which the distinguishing electron is placed is very closely related to the chemical behavior of an element and gives rise to the classification shown by the color-coding on the periodic table seen here. This last electron is called the distinguishing electron because it distinguishes an atom from the one immediately preceding it in the periodic table. Since it is the outermost (valence) electrons which are primarily involved in chemical interactions between atoms, the last electron added to an atom in the building-up process is of far more interest to a chemist than the first. The commonly used long form of the periodic table is designed to emphasize electron configurations.
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