Chemistry- JIB T10 Transition Metals

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  • Answers: +3, +2, +3, +2
  • Chemistry- JIB T10 Transition Metals

    1. 1. Chapter ____
    2. 2. <ul><li>Complexes: assemblies of a central metal ion bonded to a group of surroundings molecules or ions. Ex. [Ag(NH 3 ) 2 ] + </li></ul><ul><li>Complex Ion: If the complex carries a charge </li></ul><ul><li>Coordination Compounds: Compounds that contain complexes </li></ul>
    3. 3. <ul><li>Ligands: the molecules or ions that surround the metal ion in a complex and usually have at least one lone pair of electrons </li></ul><ul><ul><li>Ex. The 2 NH 3 ligands bonded to the Ag + </li></ul></ul><ul><li>Coordination Number: The number of donor atoms attached to a metal </li></ul>
    4. 4. <ul><li>Form one or more stable ions that have a complete d orbitals </li></ul><ul><ul><li>Recall how to write electron configurations for d orbital elements. </li></ul></ul><ul><li>Block 2B will not be considered because its only common oxidation state has a complete d orbital </li></ul><ul><li>‘ S’ electrons are the first to be removed when these metals form ions </li></ul><ul><li>Atomic radius: decreases across the period because the 3d electrons shield the 4s electrons </li></ul>
    5. 5. <ul><li>Electronegativity & Ionization energy: increases slightly </li></ul><ul><li>Closed packed structure and a very small atomic radii </li></ul><ul><ul><li>Results in a very strong metallic bond </li></ul></ul><ul><ul><li>Leads to transition metals have higher densities, melting points, and boiling points. </li></ul></ul><ul><li>Form a variety of oxidation states in their compounds </li></ul>
    6. 6. Metal +1 +2 +3 +4 +5 +6 +7 Sc Colorless Ti Violet Colorless V Violet Green blue Yellow Cr Blue Green Yellow (CrO 4 2- ) orange (Cr 2 O 7 2- Mn Pale pink Brown Dark green (MnO 4 2- ) Intense purple (MnO 4 - ) Fe Pale green Yellow or brown Co Pink Orange/yellow Ni Green Cu Blue Zn colorless
    7. 7. <ul><li>They are either polar or anions </li></ul><ul><li>Because ligands have lone pairs, they can function as Lewis bases </li></ul><ul><ul><li>This makes the metal a Lewis acid </li></ul></ul><ul><li>Ligand coordiante to the metal </li></ul><ul><ul><li>Ex. [Cu(NH 3 ) 4 ]SO 4 [Cu(NH 3 ) 4 ] 2+ CATION </li></ul></ul><ul><ul><ul><ul><ul><li> SO 4 2- ANION </li></ul></ul></ul></ul></ul>
    8. 8. <ul><li>The charge of a complex is the sum of the charges on the central atom on its surrounding ligands. </li></ul><ul><li>Try these: What is the oxidation number of the central atom in </li></ul><ul><li>[Co(NH 3 ) 5 Cl](NO 3 ) 2 </li></ul><ul><li>[Ru(NH 3 ) 5 (H 2 O)]Cl 2 </li></ul><ul><li>[Cr(NH 3 ) 6 ](NO 3 ) 3 </li></ul><ul><li>K 4 [Fe(CN) 6 ] </li></ul>
    9. 9. <ul><li>The atom of the ligand bound directly to the metal is called the donor atom </li></ul><ul><ul><li>Ex. [Ag(NH 3 ) 2 ] + N is the donor atom </li></ul></ul><ul><li>The coordination number (the number of donor atoms attached to the metal) in the above example is 2. </li></ul><ul><li>Dependent on the number of donor atoms present, ligands are classified as monodentate, bidentate, or polydentate </li></ul><ul><ul><li>Ex. Monodentate: H 2 O </li></ul></ul><ul><li> Bidentate: ethylenediamine: H 2 N-CH 2 –CH 2 –NH 2 </li></ul><ul><li>Bidentate and polydentate ligands are called chelating agents : </li></ul><ul><ul><li>They hold the metal atom like a claw. </li></ul></ul>
    10. 10. <ul><li>In naming salts, the name of the cation is given before the name of the anion. </li></ul><ul><ul><li>Ex. In [Co(NH 3 ) 5 Cl]Cl 2 , we name the [Co(NH 3 ) 5 Cl] 2+ and then Cl - . </li></ul></ul><ul><li>Within a complex ion or molecule, the ligands are named before the metal. Prefixes that give the number of ligands are not considered part of the ligand name in determining alphabetical order. </li></ul><ul><ul><li>In [Co(NH 3 ) 5 Cl] 2+ ion, the ammonia ligands are named first, then the chloride, then the metal: Pentaaminechlorocobalt (III) </li></ul></ul>
    11. 11. 3. The names of anionic ligands end in the letter O, whereas neutral ones ordinarily bears the name of the molecule. Number of Ligands Prefix 1 Mono 2 Di 3 Tri 4 Tetra 5 Penta 6 Hexa Ligand Name Cl - Chloro OH - Hydroxo NO 2 - Nitrito CN - Cyano SO 4 2- Sulfato H 2 O Aquo or aqua NH 3 Ammine CO Carbonyl NO Nitrosyl
    12. 12. <ul><li>A Greek prefix is used to indicate the number of each kind of ligand when more than one is present. If the name of the ligand itself contains a Greek prefix, such as mono- or di-, the name of the ligand is enclosed in parentheses and alternate prefixes are used, Bis-, Tris-, tetrakis-,hexakis </li></ul><ul><li>Ex. [Co(en) 3 ]Cl 3 tris(ethylenediamine)cobalt (III) chloride </li></ul><ul><li>If the complex is an anion, its name ends in –ate. </li></ul><ul><li>Ex. K 4 [Fe(CN) 6 ] hexocyanoferrate (II) ion </li></ul><ul><li>Others: Copper: Cuprate </li></ul><ul><li> Silver: Argenate </li></ul>
    13. 13. <ul><li>The oxidation number of the metal is given in parentheses in Roman numerals following the name of the metal. </li></ul><ul><li>Try naming these: </li></ul><ul><li>[Cr(H 2 O) 4 Cl 2 ]Cl </li></ul><ul><li>[Co(NH 3 ) 4 (H 2 O)CN]Cl 2 </li></ul><ul><li>Na[Al(OH) 4 ] </li></ul><ul><li>K 2 [Ni(CN) 4 ] </li></ul><ul><li>(NH 4 ) 2 [CuBr 4 ] </li></ul><ul><li>[Ni(H 2 O) 6 ]SO 4 </li></ul><ul><li>[CoCl 3 (NH 3 ) 3 ] 1- </li></ul><ul><li>[Co(NH 3 ) 6 ]Cl 3 </li></ul><ul><li>K 3 [Fe(CN) 6 ] </li></ul><ul><li>K 4 [Fe(CN) 6 ] </li></ul>
    14. 14. ☺ Central ion is first ☺ Ligands second ☺ Neutral molecules first ☺ Negative ions second ☺ Neutral molecules and polyatomic ions are always surrounded by (parentheses) , even if only 1 present ☺ Entire complex ion formula surrounded by [brackets]
    15. 15. Write the formula for the diamminepalladium(II) ion ☺ Central ion – palladium (Pd) ☺ Ligands – NH 3 (2) ☺ Written in parentheses ☺ Neutral charge ☺ Brackets around entire formula ☺ Calculate the net charge [Pd(NH 3 ) 2 ] 2+
    16. 16. Write the formula for the carbonylpentacyanoferrate(II) ion ☺ Central ion – iron (Fe) ☺ Ligands ☺ CN (5) 1- charge Written in parentheses ☺ CO (1) Neutral Written in parentheses ☺ Brackets around entire formula ☺ Calculate the net charge [Fe(CO)(CN) 5 ] 3-
    17. 17. <ul><li>Tetraammineplatinum(II) ion </li></ul><ul><ul><li>[Pt(NH 3 ) 4 ] 2+ </li></ul></ul><ul><li>Tetraiodoaurate(III) ion </li></ul><ul><ul><li>[AuI 4 ] - </li></ul></ul><ul><li>Pentacarbonylnitrosyliron(II) ion </li></ul><ul><ul><ul><ul><ul><li>[Fe(CO) 5 (NO)] 2+ </li></ul></ul></ul></ul></ul>
    18. 18. <ul><li>Ligand Exchange Reactions of Transition Metals (and Al 3+ ) </li></ul><ul><ul><li>Complex ions undergo ligand substitution reactions in solutions </li></ul></ul><ul><ul><li>Ex. [Ni(H 2 O) 6 ] 2+ + NH 3 -> [Ni(NH 3 ) 6 ] 2+ + H 2 O or </li></ul></ul><ul><ul><li>Ni 2+ + NH 3 -> [Ni(NH 3 ) 6 ] 2+ </li></ul></ul><ul><li>How do you know the number of ligands that are in the product? </li></ul><ul><ul><li>Hint: Often, not all the time!!, the number of ligands is twice the cation charge. </li></ul></ul><ul><ul><li>Also, helpful to know the following table </li></ul></ul>
    19. 19. Metal Ion Ligand Number of Ligands Fe 3+ SCN - 1 Ni 2+ NH 3 Any between 1 and 6 Ag + CN - 2 Ag + NH 3 1 or 2 Zn 2+ NH 3 4 Al 3+ OH - 3 or 4 Zn 2+ OH - 4 Cu 2+ NH 3 4 Co 2+ Cl _ 4
    20. 20. <ul><li>Decomposition of complex by acid-base neutralization </li></ul><ul><ul><li>Complexes containing NH 3 can be broken down by acid base decomposition by adding an acid </li></ul></ul><ul><ul><li>Ex. [Cu(NH 3 ) 4 ] 2+ + H + -> Cu 2+ + NH 4 + </li></ul></ul><ul><ul><ul><li>The NH 3 acts as a base (accepts H + ions to form NH 4 + ). The rest of the complex is broken down. </li></ul></ul></ul><ul><li>Go over sheet from the “Ultimate Chemical Equation Handbook.” Responsible for all the reactions listed in the transition metal section. </li></ul>

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