Ch. 23: Transition Metals and Coordination Compounds

Question 1

crystal field theory

Answer 1

It is bonding model for transition metal complex ions. The model describes how the degeneracy of the d orbitals is broken by the repulsive forces between the electrons on the ligands around the metal ion and the d orbitals in the metal ion.

Question 2

lanthanide contraction

Answer 2

The trend toward leveling off in size of the atoms in the third and fourth transition rows due to the ineffective shielding of the f sublevel electrons.

Question 3

complex ion

Answer 3

An ion that contains a central metal ion bound to one or more ligands.

Question 4

ligand

Answer 4

A neutral molecule or an ion that acts as a Lewis base with the central metal ion in a complex ion.

Question 5

coordination compound

Answer 5

A neutral compound made when a complex ion combines with one or more counter ions.

Question 6

primary valence

Answer 6

The oxidation state on the central metal atom in a complex ion.

Question 7

secondary valence

Answer 7

The number of molecules or ions directly bound to the metal atom in a complex ion; also called the coordination number.

Question 8

coordination number

Answer 8

The number of atoms with which each atom in a crystal lattice is in direct contact.

Question 9

coordinate covalent bond

Answer 9

The bond formed when a ligand donates electrons to an empty orbital of a metal in a complex ion.

Question 10

monodentate

Answer 10

Describes ligands that donate only one electron pair to the central metal.

Question 11

bidentate

Answer 11

Describes ligands that donate two electron pairs to the central metal.

Question 12

polydentate

Answer 12

Describes ligands that donate more than one electron pair to the central metal.

Question 13

chelate (“key-late”)

Answer 13

A complex ion that contains either a bi- or polydentate ligand.

Question 14

chelating agent

Answer 14

The coordinating ligand of a chelate.

Question 15

Guidelines for Naming Complex Ions

Answer 15

1. Name the ligands.
   * Name neutral ligands as molecules with the following notable exceptions.

_{H2O (aqua)}

_NH3(ammine)

_{CO (carbonyl)}

• Name anionic ligands with the name of the ion plus an ending modified as follows:

_{-ide becomes -o}

_{-ate becomes -ato}

_{-ite becomes -ito}

2. List the names of the ligands in alphabetical order before the name of the metal cation.
3. Use a prefix to indicate the number of ligands (when there is more than one of a particular type): di- (2), tris- (3), tetra- (4), penta- (5), or hexa- (6). If the name of the ligand already contains a prefix, such as ethylenediamine, place parentheses around the ligand name and use bis- (2), tris- (3), or tetrakis- (4) to indicate the number. Prefixes do not affect the order in which you list the ligands.
4. Name the metal.
   a. When the complex ion is a cation, use the name of the metal followed by the oxidation state written with a Roman numeral.
   b. If the complex ion is an anion, drop the ending of the metal and add -ate followed by the oxidation state written with a Roman numeral. Some metals use the Latin root with the ate ending.
5. Write the entire name of the complex ion by listing the ligands first followed by the metal.

Question 16

Names and formulas of common ligands

Answer 16

Question 17

Names of common metals when found in anionic complex ions

Answer 17

Question 18

structural isomers

Answer 18

Molecules with the same molecular formula but different structures.

Question 19

steroisomers

Answer 19

Molecules in which the atoms are bonded in the same order but have a different spatial arrangement.

Question 20

coordination isomers

Answer 20

Isomers of complex ions that occur when a coordinated ligand exchanges places with the uncoordinated counterion.

Question 21

linkage isomers

Answer 21

Isomers of complex ions that occur when some ligands coordinate to the metal in different ways.

Question 22

geometric isomers

Answer 22

For complex ions, isomers that result when the ligands bonded to the metal have a different spatial arrangement. Cis-trans isomerism occurs in square planar complexes of the general formula MA₂B₂ or octahedral complexes of the general formula MA₄B₂. Fac-mer isomerism, which occurs in octaheral complexes of the general formula MA₃B₃.

Question 23

optical isomers

Answer 23

Two molecules that are nonsuperimposable mirror images of one another.

Question 24

strong-field complexes

Answer 24

A complex ion in which the crystal field splitting is large.

CN^- > NO₂^- > en > NH₃

Question 25

weak-field complex

Answer 25

A complex ion in which the crystal field splitting is small.

H₂O > OH^- > F^- > Cl^- > Br^- > I^-

Question 26

low-spin complexes

Answer 26

A complex ion that has strong field ligands and has fewer unpaired electrons relative to the free metal ion.

Question 27

high-spin complex

Answer 27

A complex ion with weak field ligands that have the same number of unpaired electrons as the free metal ion.