Acidity periodic trends

The binary acids of non-metals exhibit periodic trends in their acid strength, as shown in Figure 8.5. Two factors are responsible for this trend the electronegativity of the atom that is bonded to hydrogen, and the strength of the bond. 

The binary acids show periodic trends, which are related to electronegativity and bond strength. 

The oxides of main-group elements show periodic trends in properties. Oxides of metals tend to be ionic and to form basic solutions in water. Oxides of nonmetals are molecular and the anhydrides of acids. 

Periodic Trends Acid-Base Behavior of Oxides movie... 

Periodic trends in the strength of binary acids are summarized in Figure 15.10. 

Covalent oxides at high oxidation states and high electronegativities form the strongest acids. For this skill, note that the periodic trends for acid and base strength of the oxide of an element follows the same pattern we ve seen before. 

For example, hydrogen chloride, also known as hydrochloric acid, has a low melting point and a low boiling point. (It is a gas at room temperature.) These properties might lead you to believe that hydrogen chloride is a covalent compound. Hydrogen chloride, however, is extremely soluble in water, and the water solution conducts electricity. These properties are characteristic of an ionic compound. Is there a clear, theoretical way to decide whether the bond between hydrogen and chlorine is ionic or covalent The answer lies in a periodic trend. 

Since tropolones and 3-hydroxy-4-pyrones are taken in this chapter to be enols, we now cite their binding as enolato ligands to lanthanum and all the other trivalent lanthanides (save the radioactive promethium) " " . Likewise, we note such studies for complexes with enolato ligands derived from 3-acetyl-4-hydroxycoumarin, dehydroacetic acid and their oximes, and with the aromatic enediolates, squarate and croconate. Periodic trends in thermodynamic parameters were reported and analyzed in these studies. 

To decide which hydrogen is most acidic, first determine what element each hydrc en is bonded to and then decide its acidity based on periodic trends. For example, CH3NHCH2CH2CH2CH3 contains only C-H and N-H bonds. Since the acidity of H-A increases across a row of the periodic table, the single H on N is the most acidic H in this compound. 

Step [1] Identify the atoms bonded to hydrogen, and use periodic trends to assign relative acidity. 

Write electron configurations of transition metal atoms and ions compare periodic trends in atomic properties of transition elements with those of main-group elements explain why transition elements have multiple oxidation states, how their metallic behavior (type of bonding and oxide acidity) changes with oxidation state, and why many of their compounds are colored and paramagnetic ( 22.1) (SP 22.1) (EPS 22.1 -22.17)... 

From the diolate complexes the free diols can be released by hydrolysis with hydrochloric acid. The diols reveal as-addition of the two hydroxyl groups, lire rhenium complex [Re0Cl(0CH2CH20)(phen) ° undergoes the reverse reaction by thermolysis, releasing ethylene and producing [Re03Cl(phen)]°. The results are consistent with the periodic trends for second and third row transition elements of similar environments in which the second row elements are more easily reduced and the third row elements are more easily oxidized [29],... 

The periodic trends in the acid strengths of binary compounds of hydrogen and the nonmetals of periods 2 and 3 are summarized in FIGURE 16.17. 

FIGURE 3.3 A summary of periodic trends in relative acidity. Acidity increases from left to right across a given row (electronegativity effect) and from top to bottom in a given column (bond strength effect) of the periodic table. 

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