Inorganic Chemistry Exam 1, Chapters 1 and 2 – Flashcards
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Covalent radius
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1/2 the internuclear distance 1/2 the length of the covalent bond For a bond between 2 identical atoms
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Ionic radii of cations/anions
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The sums of the ionic radii
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Van der waals radius
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1/2 the internuclear distance to the nearest Cl nucleus in the next molecule
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Sizes of radii
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Cationic < covalent < anionic = van der waals Difference of 60pm between each type
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Horizontal trend of atomic radii
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Decrease moving from L to R More protons pull electrons closer, causing a smaller radius
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Vertical trend of atomic radii
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Increase from top to bottom
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Scandide contraction
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Nonexpansion in period 4 Involves Al and Ga
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Lanthanide contraction
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Nonexpansion in period 6
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Bronsted-Lowry acid
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Proton donor (becomes conj base)
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Bronsted-Lowry base
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Proton acceptor (becomes conj acid)
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Amphiprotic
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Something that is both basic and acidic, but not strongly either
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6 strong acids
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1. HCl 2. HBr 3. HI 4. H2SO4 5. HClO4 6. HNO3
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Lower pKa
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Lower pH = MORE ACIDIC
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Lower pKb
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Higher pH = MORE BASIC
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Strong acids produce?
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A weak conjugate base
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Weak acids produce?
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A strong conjugate base
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Nonacidic cations
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pKa > 14 Do not alter pH of solution
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Feebly acidic cations
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pKa between 11.5 and 14
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Weakly acidic cations
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pKa between 6 and 11.5
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Moderately acidic cations
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pKa between 1 and 6
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Strongly acidic cations
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pKa between -4 and 1 React violently and exothermically
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Very strongly acidic cations
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pKa < -4 Cannot actually exist in solution
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Acidity of a metal cation solution depends on?
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1. charge 2. radius 3. electronegativity
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Charge and acidity of metal cations
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As charge increases, acidity strongly increases due to increased interaction and more dissociation
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Radius and acidity of metal cations
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As radius increases, acidity decreases Increased stability of cation leads to less interactions
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Electronegativity and acidity of metal cations
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As electronegativity increases, acidity increases
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Hydration enthalpies of cations are affected by?
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1. charge 2. radius 3. electronegativity
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Charge and hydration enthalpies of cations
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As charge increases, deltaH gets more negative, acidity increases Charge has the biggest effect on deltaH!!!!!!!!!
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Radius and hydration enthalpies of metal cations
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As radius increases, deltaH gets less negative, acidity decreases`
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Electronegativity and hydration enthalpies of metal cations
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As electronegativity increases, deltaH gets more negative and acidity increases
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Maximum coordination number
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The max number of atoms bound to the central atom Depends on the size of the atoms bound to the central atom Generally increases moving down the periodic table
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Maximum coordination number for period 2
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4
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Maximum coordination number for periods 3 and 4
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6
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Maximum coordination number for periods 5 and 6
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> 6, usually 8
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When maximum coordination number is met?
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No reaction will occur in water due to steric hindrance
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Why do some elements have lower than normal coordination numbers?
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Ions in periods 5 and 6 (Ag+, Sn3+, Hg+, Au+) attach as few as 2 water molecules The polarizing power of the cationic charge is concentrated on fewer water molecules Each water molecule is more polarized, leading to HIGHER THAN EXPECTED ACIDITY.
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Henderson-Hasselbach equation
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pH = pKa + log [conj base]/[conj acid]
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Equivalence point
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When moles of acid = moles of base In titration NOT IMPORTANT
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Half-equivalence point
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When concentrations of acid and base are equal pH at this point = pH at right boundary = pKa1
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Predominance diagram
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Anions on R Cations on L
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Predominance diagrams and predicting reactions
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If there is no overlap, the reactants cannot coexist as predominant forms in the same pH, so a reaction will occur (proton transferred L to R) If there is overlap, the reactants can coexist so there will be NO REACTION
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Nomenclature of group 16 hydrides
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H2S: hydrogen sulfide H2Se: hydrogen selenide H2Te: hydrogen telluride
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Nomenclature of group 14 hydrides
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End in "-ane" Plumbane, stannane, germane, silane Formulas written w/ H+ last to show that they are not predominantly acidic
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Nomenclature of group 15 hydrides
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End in "-ine" Bismuthine, arsine, phosphine Formulas written with H+ last to show that they are not predominantly acidic
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Nomenclature of group 17: hydrogen halides
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In solution, they undergo acid dissociation and are named as hydrohalic acids
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Predominance diagram of a nonacidic cation
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Cation is predominant at all pH values
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Predominance diagram of a feebly acidic cation
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Precipitates hydroxides from 1M solutions at pH > 11.5-14
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Predominance diagram of a weakly acidic cation
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Precipitates metal hydroxides at pH 6-11.5 (neutral to slightly basic
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Predominance diagram of a moderately acidic cation
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Cation is predominant in solution at pH 1-6, ppt forms if the solution is not kept acidic
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Predominance diagram of a strongly acidic cation
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Cation is predominant in solution at pH -4 to 1 At most practical pH values there is a metal hydroxide ppt
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Predominance diagram of a very strongly acidic cation
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Cannot exist in water because it is impossible to have a pH that low in water
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As concentration decreases?
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The range of soluble species increases!!!
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Hydrated anions
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A H bond forms between a H on the water and the metal anion, ripping the H off the water molecule and producing OH- to form a basic solution
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Nonbasic anions
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pKb > 14 No detectable basicity Cl-, Br-, I- No tendency to combine with H+ ions in solution So much less basic than water that they cannot compete with water for H+ ions
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Feebly basic anions
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pKb values 11.5-14 No examples
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Weakly basic anions
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pKb values 6-11.5 Includes F-
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Moderately basic anions
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pKb values 1-6 Te2-
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Strongly basic anions
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pKb values -4 to 1 Se2-, S2-
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Very strongly basic anions
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pKb < -4 React irreversibly with water O2- + H2O = 2OH-
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Factors that affect basicity of anions
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1. charge 2. radius
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Charge and basicity of anions
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As the charge gets larger and more negative, the basicity increases Basicity increases moving L to R across a period
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Radius and basicity of anions
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As radius increases, basicity decreases Basicity decreases moving down a group
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Periodic trends in basicity
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The further up and into the periodic table an element is, the more reactive its ion is (as long as charge is increasing)
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Reactions between strong acids and bases
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React to give species with overlapping ranges closer to the center of the predominance diagram
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