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Questions and Answers

What is the overall charge of the CrO4^2- oxoanion?

  • -3
  • 0
  • -2 (correct)
  • -1
  • What type of bond is formed between the metal ion and ligands in a coordination complex?

  • Ionic bond
  • Metallic bond
  • Coordinate bond (correct)
  • Hydrogen bond
  • Which of the following best describes the geometric arrangement of Cr6+ in the CrO4^2- oxoanion?

  • Linear
  • Trigonal planar
  • Octahedral
  • Tetrahedral (correct)
  • Which statement about ligands in coordination complexes is true?

    <p>Ligands donate electron pairs to the central metal ion.</p> Signup and view all the answers

    Which oxidation state of chromium is considered the most stable?

    <p>Cr3+</p> Signup and view all the answers

    Which of the following correctly describes a coordination compound?

    <p>A compound that contains a coordination complex and maintains charge balance.</p> Signup and view all the answers

    Which statement accurately describes the transformation from chromate to dichromate?

    <p>It requires acidic conditions to occur.</p> Signup and view all the answers

    What role does dichromate Cr2O7^2- play in redox reactions strongly?

    <p>It acts as a strong oxidizer.</p> Signup and view all the answers

    In the dissociation of the coordination compound [Co(NH3)6]Cl3, which ions are produced?

    <p>[Co(NH3)6]3+ and 3 Cl-</p> Signup and view all the answers

    Why are coordination complexes considered to behave as electrolytes in solution?

    <p>They produce anions and cations that can conduct electricity.</p> Signup and view all the answers

    What is indicated by the presence of square brackets in a formula of a coordination complex?

    <p>The species inside forms a coordination complex.</p> Signup and view all the answers

    Counter ions in coordination compounds primarily serve to:

    <p>Balance the overall charge of the compound.</p> Signup and view all the answers

    What distinguishes the role of the central metal ion in a coordination complex?

    <p>It receives electron pairs from ligands.</p> Signup and view all the answers

    What is the coordination number for a tetrahedral complex?

    <p>4</p> Signup and view all the answers

    Which geometry corresponds to a coordination number of 5?

    <p>Trigonal bipyramidal</p> Signup and view all the answers

    If a complex has a charge of +1 and includes two chloride ligands, what is the oxidation state of the metal?

    <p>+3</p> Signup and view all the answers

    Which of the following is NOT a geometry associated with 4 donor atoms in coordination complexes?

    <p>Bipyramidal</p> Signup and view all the answers

    What is the oxidation state of cobalt in the complex cation [Co(NH3)6]3+?

    <p>3</p> Signup and view all the answers

    Which coordination complex geometry is most commonly associated with a coordination number of 6?

    <p>Octahedral</p> Signup and view all the answers

    Which coordination number is exhibited by the complex [Co(NH3)6]Cl3?

    <p>6</p> Signup and view all the answers

    In determining the oxidation state of a metal, which of the following components must be considered?

    <p>The complex charge and the sum of the ligand charges</p> Signup and view all the answers

    Which of these geometries can potentially occur with a coordination number of 4?

    <p>Tetrahedral and square planar</p> Signup and view all the answers

    In the complex [Co(NH3)4Cl2]+, what would be the spatial arrangement if the two chloride ligands are positioned opposite each other?

    <p>Trans</p> Signup and view all the answers

    What aspect of coordination complexes primarily dictates their geometry?

    <p>The nature and number of donor atoms</p> Signup and view all the answers

    What role does nitrogen play in the NH3 ligand in coordination compounds?

    <p>Donor atom</p> Signup and view all the answers

    In a coordination compound with ligands such as ammonia and chloride, what is the characteristic charge of ammonia?

    <p>0</p> Signup and view all the answers

    According to Kepert theory, which factor is primarily responsible for the geometries of coordination complexes?

    <p>Repulsion of ligands</p> Signup and view all the answers

    Which of the following statements correctly describes the nature of chlorides in the complex [CoCl2(NH3)4]Cl?

    <p>Chlorides are ionic counter ions</p> Signup and view all the answers

    Which term describes the number of donor atoms surrounding a central metal atom in a coordination complex?

    <p>Coordination number</p> Signup and view all the answers

    What is the geometry of the complex [Co(NH3)6]3+?

    <p>Octahedral</p> Signup and view all the answers

    For the complex [Co(NH3)4Cl2]+, how many isomers are theoretically possible?

    <p>2</p> Signup and view all the answers

    What does a coordination number of 6 indicate about the arrangement of donor atoms around the metal center?

    <p>They form an octahedral geometry</p> Signup and view all the answers

    What is the effect of increasing the oxidation state of chromium on its electronegativity?

    <p>It increases.</p> Signup and view all the answers

    Which oxidation state of chromium is associated with the highest ionization energy?

    <p>Cr6+</p> Signup and view all the answers

    What property of CrO3 categorizes it as a strong oxidizing agent?

    <p>It contains Cr6+.</p> Signup and view all the answers

    What characteristic is true of Cr2O3?

    <p>It is amphoteric.</p> Signup and view all the answers

    Who is known as the 'Father of Coordination Chemistry'?

    <p>Alfred Werner</p> Signup and view all the answers

    What concept did Alfred Werner introduce in relation to coordination compounds?

    <p>Coordination number</p> Signup and view all the answers

    What characterizes the behavior of metal ions within coordination complexes?

    <p>They are surrounded by other molecules/anions.</p> Signup and view all the answers

    Which property of chromium oxoanions generally increases with the oxidation state of chromium?

    <p>Electronegativity</p> Signup and view all the answers

    What is the main focus of research regarding chromium in health applications?

    <p>Its long-term impact of diet pills</p> Signup and view all the answers

    Which of these statements is correct about the acidity of chromium compounds?

    <p>Chromium compounds become more acidic with increasing oxidation states.</p> Signup and view all the answers

    Study Notes

    Coordination Complexes

    • Coordination complexes consist of a central metal cation bonded to ligands.
    • The metal cation acts as a Lewis acid, accepting an electron pair from the ligand.
    • Ligands act as Lewis bases, donating an electron pair to the metal cation.
    • The bond formed between the metal and ligand is called a coordinate covalent bond or dative bond.
    • Counter ions may be present to balance the charge of the complex, forming a coordination compound.

    ### Components of Coordination Complexes

    • Coordination Number (C.N.) is the number of donor atoms surrounding the metal ion.

    Geometry

    • Coordination complex geometries are determined by the coordination number and ligand arrangement.
    • Common geometries include:
      • Linear (2 donor atoms)
      • Trigonal planar (3 donor atoms)
      • Tetrahedral (4 donor atoms)
      • Square planar (4 donor atoms - exception)
      • Trigonal bipyramidal (5 donor atoms)
      • Octahedral (6 donor atoms)

    Calculating Oxidation States

    • Metal oxidation state can be calculated by considering:
      • The charge of the complex
      • The charges of the ligands

    Alfred Werner and Coordination Chemistry

    • Alfred Werner is considered the "father of coordination chemistry."
    • He introduced the concept of coordination number and explained the existence of isomers in coordination complexes.
    • He proposed that some metal complexes were not simple ionic salts, but rather, had specific geometries with ligands surrounding the central metal ion.

    Chromium Oxoanions

    • Oxoanions are negatively charged ions that contain oxygen and one or more other elements.
    • Chromium exists in various oxidation states, from +2 to +6.
    • Chromium (+6) forms chromate (CrO42-) and dichromate (Cr2O72-), both of which are strong oxidizing agents.
    • Cr(+3) is the most stable oxidation state.
    • Cr(+2) and Cr(0) are strong reducing agents, easily oxidizing to Cr(+3).

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    Description

    Explore the fascinating world of coordination complexes, where a central metal cation bonds with ligands. This quiz covers the definition, components, and geometrical arrangements of these complexes, including coordination numbers and common geometries. Test your knowledge and deepen your understanding of this essential chemistry topic!

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