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Key Concepts PowerPoint

Chapter 20
Transition Elements and Coordination Chemistry

 
20-01
Title
The transition elements
Caption
Figure 20.1 The transition elements (d-block elements, shown in yellow) are located in the central region of the periodic table between the s-block and p-block main-group elements. The two series of inner transition elements (f-block elements, shown in green) follow lanthanum and actinium.
Notes
Transition elements located in the central region of the periodic table
Keywords
transition elements, d-block elements
20-01-01UN
Title
Electron configurations of Cr and Cu
Caption
Anomalous electron configurations frequently occur if the atom can attain half-filled or completely filled subshells.
Notes
The electron configurations of chromium and copper deviate from the expected filling pattern for the subshells.
Keywords
chromium, copper, electron configuration
20-01-03UN
Title
Key Concept Problem 20.2
Caption
On the periodic table below, locate the transition metal atom or ion with the following electron configurations. Identify each atom or ion.
Notes
Key Concept Problem 20.2
Keywords
electron configurations
20-02
Title
Properties of transition elements
Caption
Figure 20.2 Relative melting points of the transition elements. Melting points reach a maximum value in the middle of each series.
Notes
Within any transition series, the melting points increase for the first three or four elements, then show a general decrease.
Keywords
melting points
20-03
Title
Atomic radii
Caption
Figure 20.3 Atomic radii (in pm) of the transition elements. The radii decrease with increasing atomic number and then increase again toward the end of each transition series. Note that the second-and third-series transition elements have nearly identical radii.
Notes
Due to the lanthanide contraction, second-and third-series transition elements have similar atomic radii, so the heavier third-series elements are much denser than the lighter second-series elements.
Keywords
atomic radii, lanthanide contraction, density
20-04
Title
Lanthanide atomic radii
Caption
Figure 20.4 Atomic radii (in pm) of the lanthanide elements. The radii generally decrease with increasing atomic number.
Notes
Atomic radii of the lanthanide elements.
Keywords
lanthanides, atomic radii
20-05
Title
Transition metal densities
Caption
Figure 20.5 Relative densities of the transition metals. Density initially increases across each series and then decreases.
Notes
Relative densities of the transition metals. The densities of the transition metals are inversely related to their atomic radii.
Keywords
density, atomic radii
20-06
Title
Oxidation states
Caption
Figure 20.6 Common oxidation states for first-series transition elements. The states encountered most frequently are shown in red. The highest oxidation state for the group 3B-7B metals is their periodic group number, but the group 8B transition metals have a maximum oxidation state less than their group number. Most transition elements have more than one common oxidation state.
Notes
Common oxidation states for first-series transition elements. All first-series transition metals except scandium form +2 ions.
Keywords
oxidation state, first-series
20-08-01UN
Title
Acid strength of chromium hydroxides
Caption
Chromium(III) hydroxide is amphoteric; however, chromium(II) hydroxide is a typical basic hydroxide which dissolves in acid solution but not in excess base. Chromium(VI) hydroxide (chromic acid) is a strong acid.
Notes
The higher the oxidation state of the central atom, the more acidic the hydroxo species.
Keywords
metal hydroxide, acidity, oxidation state
20-09-01UN
Title
Chromate and dichromate ions
Caption
Ball-and-stick models of the chromate ion, CrO42-, and dichromate ion, Cr2O72-.
Notes
Structures of the chromate ion, CrO42-, and dichromate ion, Cr2O72-
Keywords
chromate, dichromate
20-11
Title
Complexes of copper
Caption
Figure 20.11 When an aqueous solution of CuSO4 (left) is treated with aqueous ammonia, a blue precipitate of Cu(OH)2 forms (center). On the addition of excess ammonia, the precipitate dissolves, yielding the deep blue Cu(NH3)42+ion (right).
Notes
Three test tubes showing the different copper(II) complexes
Keywords
copper
20-12
Title
Coordination geometries of metal complexes
Caption
Figure 20.12 The arrangement of ligand donor atoms (L) in MLn complexes with coordination numbers 2, 4, and 6. In the octahedral arrangement, four ligands are at the corners of a square, with one more above and one below the plane of the square.
Notes
Coordination geometries of metal complexes, showing linear, tetrahedral, square planar, and octahedral geometries
Keywords
coordination geometry
20-12-01UN
Title
Structure of the [Pt(NH3)Cl5]-ion
Caption
Ball-and-stick model of the [Pt(NH3)Cl5]-ion.
Notes
Structure of the [Pt(NH3)Cl5]-ion, for Worked Example 20.3
Keywords
platinum, coordination compound
20-13
Title
Common ligands
Caption
Figure 20.13 Structures of some common ligands. Ligand donor atoms are in color. The thiocyanate ion can bond to a metal through either the S atom or the N atom.
Notes
Structures and coordinating abilities of some common ligands
Keywords
ligand, coordination compound
20-14
Title
Chelating ligands of cobalt(III) complexes
Caption
Figure 20.14 (a) Molecular model and (b) shorthand representation of the [Co(en)3]3+ion. The complex contains three cobalt-ethylenediamine chelate rings. In (b), the symbol N-N represents a bidentate NH2CH2CH2NH2 ligand, which spans adjacent corners of the octahedron. (c) Molecular model and (d) shorthand representation of the [Co(EDTA)]-ion. The hexadentate EDTA4-ligand uses its two N atoms and four O atoms to bond to the metal, thus forming five chelate rings.
Notes
Ethylenediamine and EDTA as chelating ligands on cobalt(III)
Keywords
chelate, ethylenediamine, EDTA
20-15
Title
The porphine molecule
Caption
Figure 20.15 (a) The structure of the porphine molecule. Loss of the two NH protons gives a planar, tetradentate 2-ligand that can bond to a metal cation. The porphyrins are derivatives of porphine in which the peripheral H atoms are replaced by various substituent groups. (b) Schematic of the planar heme group, the attached protein chain, and the bound O2 molecule in oxyhemoglobin and oxymyoglobin. The Fe(II) ion has a six-coordinate, octahedral environment, and the O2 acts as a monodentate ligand.
Notes
Structural similarity between the porphine molecule and the porphyrin heme
Keywords
porphine, porphyrin, heme
20-15-01UN
Title
Naming coordination compounds
Caption
Three examples illustrating the trend in the nomenclature of coordination compounds.
Notes
Older literature named the ligand water aquo instead of aqua. However, the ending -o implies an anionic ligand. Ammonia as a ligand has the name ammine, with two m's. If one or more of the hydrogen atoms are replaced by groups of atoms bonded through carbon, the resulting ligand is an organic amine, with one m.
Keywords
coordination compounds, nomenclature
20-16
Title
Isomerism of coordination compounds
Caption
Figure 20.16 Classification scheme for the kinds of isomers in coordination chemistry. See the text for examples.
Notes
Isomers have the same chemical formula but different physical and chemical properties
Keywords
isomers
20-17
Title
Linkage isomers
Caption
Figure 20.17 Samples and structures of (a) the nitro complex [Co(NH3)5(NO2)]2+, which contains an N-bonded NO2-ligand, and (b) the nitrito complex [Co(NH3)5(ONO)]2+, which contains an O-bonded NO2-ligand.
Notes
Linkage isomers arise when a ligand can bond to a metal through either of two different donor atoms
Keywords
isomers
20-18
Title
Diastereomers of cisplatin
Caption
Figure 20.18 Diastereoisomers of the square planar complex Pt(NH3)2Cl2. The two compounds have the same connections among atoms but different arrangements of the atoms in space.
Notes
Cis and trans isomers of cisplatin
Keywords
diastereomers, cisplatin
20-19
Title
Diastereomers of [Co(NH3)4Cl2]+
Caption
Figure 20.19 Diastereoisomers of the Co(NH3)4Cl2]+ion. Although they may appear different, cis isomers (a) and (b) are identical, as can be seen by rotating the entire complex by 90° about a Cl-Co-NH3 axis. Similarly, trans isomers (c) and (d) are identical.
Notes
When counting diastereomers, students frequently arrive at too many because they draw the same isomer in different orientations.
Keywords
diastereomers
20-19-01
Title
Structure of [Pt(NH3)3Cl]+
Caption
Formula and ball-and-stick model of [Pt(NH3)3Cl]+.
Notes
Structure of [Pt(NH3)3Cl]+ for Worked Example 20.6
Keywords
isomers
20-19-03
Title
Cis and trans isomers
Caption
Ball-and-stick models of the cis/trans isomers of Pt(NH3)2Cl(NO2).
Notes
Structures of the cis and trans isomers of Pt(NH3)2Cl(NO2) for Worked Example 20.6
Keywords
isomers
20-19-04
Title
Cis and trans isomers
Caption
Formulas and ball-and-stick models of [Pt(NH3)4ClBr]2+.
Notes
Structures of the cis/trans isomers of [Pt(NH3)4ClBr]2+for Worked Example 20.6
Keywords
isomers
20-19-05
Title
Diastereomers of Co(NH3)3Cl3
Caption
Ball-and-stick models of the diastereomers of Co(NH3)3Cl3.
Notes
Structures of the diastereomers of Co(NH3)3Cl3 for Worked Example 20.7
Keywords
diastereomers
20-19-07UN
Title
Key Concept Example 20.8
Caption
Consider the following isomers of the [Co(NH3)4(H2O)Cl]2+ion:
Notes
Key Concept Example 20.8
Keywords
isomers
20-19-08UN
Title
Solution to Example 20.8
Caption
Isomers 1 and 4 are identical, as can be seen by rotating 1 counterclockwise by 90 degrees about the vertical axis.
Notes
Solution to Key Concept Example 20.8
Keywords
isomers
20-19-09UN
Title
Solution to Example 20.8
Caption
Isomers 2 and 3 differ from 1 and 4 and are identical, as can be seen by rotating 2 clockwise by 90 degrees about the x axis and then counterclockwise by 90 degrees about the y axis.
Notes
Solution to Key Concept Example 20.8
Keywords
isomers
20-19-10UN
Title
Key Concept Problem 20.9
Caption
Which of the following isomers of [Co(en)(NH3)3Cl]2+are identical, and which are different?
Notes
Key Concept Problem 20.9
Keywords
isomers
20-20
Title
Chirality
Caption
Figure 20.20 The meaning of a symmetry plane: An achiral object like the coffee mug has a symmetry plane passing through it, making the two halves mirror images. A chiral object like the hand has no symmetry plane because the two “halves” of the hand are not mirror images.
Notes
Chirality, or handedness, requires the lack of a plane of symmetry
Keywords
chirality
20-21
Title
Chiral and achiral cobalt complexes
Caption
Figure 20.21 The structures of the [Co(en)3]3+enantiomers and the achiral [Co(NH3)6]3+ion. [Co(en)3]3+has a helical structure in which the three en ligands lie along the threads of a screw. As the red arrows show, one enantiomer is “right-handed” in the sense that the screw would advance into the page as you rotated it to the right. The other enantiomer is “left-handed” because it would advance into the page as you rotated it to the left. In contrast, [Co(NH3)6]3+has several symmetry planes and is achiral. (Only one of the symmetry planes is identified.)
Notes
Enantiomers are isomers that are nonsuperimposable mirror images of one another. Locating a plane of symmetry within a molecule or complex means that the species is achiral and has no stereoisomers.
Keywords
enantiomers
20-22
Title
Structure of a polarimeter
Caption
Figure 20.22 The essential features of a polarimeter. The polarimeter measures the angle through which the plane of plane-polarized light is rotated when the light is passed through a solution of a chiral substance.
Notes
A polarimeter is an instrument used to measure the magnitude and direction of rotation of plane-polarized light by a chiral sample
Keywords
chirality, optical isomers
20-22-01UN
Title
Worked Example 20.9
Caption
The possible diastereomers and enantiomers of [Co(en)2Cl2]+ion.
Notes
Solution to Worked Example 20.9
Keywords
stereoisomers
20-22-02UN
Title
Key Concept Problem 20.11
Caption
Consider the following ethylenediamine complexes of rhodium:
Notes
Key Concept Problem 20.11
Keywords
stereoisomers
20-25
Title
Absorption spectrum
Caption
Figure 20.25 (a) A solution that contains the [Ti(H2O)6]3+ion. (b) Visible absorption spectrum of the [Ti(H2O)6]3+ion.
Notes
The color of a complex corresponds to wavelengths of light that are not absorbed by the complex. The observed color is usually the complement of the color absorbed. If all wavelengths of light are absorbed, a complex appears black. If no wavelengths of light are absorbed, a complex appears white (colorless).
Keywords
absorption spectrum
20-26
Title
The color of a substance
Caption
Figure 20.26 Using an artist’s color wheel, we can determine the observed color of a substance from the color of the light absorbed. Complementary colors are shown on opposite sides of the color wheel, and an approximate wavelength range for each color is indicated. Observed and absorbed colors are generally complementary. For example, if a complex absorbs only red light of 720 nm wavelength, it has a green color.
Notes
The color of a substance is usually the complement of the color absorbed by a substance
Keywords
color, absorption spectrum
20-26-01UN
Title
Valence bond theory
Caption
The bonding in metal complexes arises when a filled ligand orbital containing a pair of electrons overlaps a vacant hybrid orbital on the metal ion to give a coordinate covalent bond.
Notes
Valence bond theory applied to bonding in metal complexes
Keywords
valence bond theory
20-26-02UN
Title
Orbital diagram for Co2+
Caption
A free Co2+ion has the electron configuration [Ar] 3d7, and its orbital diagram is:
Notes
Orbital diagram for Co2+
Keywords
bonding, valence bond theory
20-26-03UN
Title
Orbital Diagram for [CoCl4]2--
Caption
The orbital diagram represents the bonding in the complex, showing the hybridization of the metal orbitals (for the tetrahedral geometry) and the four pairs of ligand electrons, now shared in the bonds between the metal and the ligands:
Notes
Orbital diagram for tetrahedral complex [CoCl4]2--
Keywords
bonding, tetrahedral
20-26-04UN
Title
Orbital diagram for Ni2+
Caption
A free Ni2+ion has eight 3d electrons, two of which are unpaired in accord with Hund's rule.
Notes
Orbital diagram for Ni2+
Keywords
bonding
20-26-05UN
Title
Orbital diagram for [Ni(CN)4]2-
Caption
In square planar complexes, the metal uses a set of four hybrid orbitals called dsp2 hybrids, which point toward the four corners of a square.
Notes
Although both have a coordination number of four, the metal ions in square planar and tetrahedral complexes require different hybrid orbitals because of the differences in the orientation of the ligands.
Keywords
bonding, square planar
20-26-06UN
Title
Orbital diagram for Co3+
Caption
A free Co3+ion has six 3d electrons, four of which are unpaired.
Notes
Orbital diagram for Co3+
Keywords
bonding
20-26-07UN
Title
Orbital diagram for [CoF6]3-
Caption
The octahedral geometry of the [CoF6]3-ion requires sp3d2 hybrid orbitals.
Notes
Orbital diagram for octahedral complex [CoF6]3-; this complex is referred to as a high-spin complex because the d electrons are arranged according to Hund's rule to give the maximum number of unpaired electrons.
Keywords
bonding, octahedral, high-spin
20-26-08UN
Title
Orbital diagram for [Co(CN)6]3-
Caption
Since magnetic measurements of this complex indicate it is diamagnetic, the octahedral geometry is accomplished through a different set of hybrid orbitals called the d2sp3 hybrids.
Notes
Orbital diagram for octahedral [Co(CN)6]3-; this complex is referred to as a low-spin complex since the d electrons are paired up to give a maximum number of doubly occupied d orbitals and a minimum number of unpaired electrons.
Keywords
bonding, octahedral, low-spin
20-26-09
Title
Worked Example 20.10
Caption
Ball-and-stick model of the [V(NH3)6]3+ion.
Notes
Structure of the [V(NH3)6]3+ion for Worked Example 20.10
Keywords
valence bond theory
20-27
Title
Octahedral crystal field model
Caption
Figure 20.27 Crystal field model of the octahedral [TiF6]3-complex. The metal ion and ligands are regarded as charged particles held together by electrostatic attraction. The ligands lie along the x, y, and z directions.
Notes
Crystal field theory is an electrostatic model. Valence bond theory is an orbital overlap model.
Keywords
crystal field theory
20-28
Title
The five d orbitals
Caption
Figure 20.28 The shapes of the five d orbitals and their orientation with respect to an octahedral array of charged ligands.
Notes
The lobes of the orbitals indicate regions of space where a d electron is most likely to be found
Keywords
crystal field theory
20-29
Title
Crystal field splitting
Caption
Figure 20.29 A d-orbital energy level diagram for a free metal ion and a metal ion in an octahedral complex. In the absence of ligands, the five d orbitals have the same energy. When the metal ion is surrounded by an octahedral array of ligands, the d orbitals increase in energy and split into two sets that are separated in energy by the crystal field splitting, D. The d orbitals whose lobes point directly toward the ligands (dz2 and dx2 -y2) are higher in energy than the d orbitals whose lobes point between the ligands (dxy, dxz, and dyz).
Notes
Crystal field splitting between two sets of d orbitals
Keywords
crystal field splitting
20-29-01UN
Title
Energy transitions in crystal field splitting
Caption
When [Ti(H2O)6]3+absorbs blue-green light with a wavelength of about 500 nm, the absorbed energy promotes the d electron to one of the higher-energy orbitals.
Notes
Energy transitions in crystal field splitting
Keywords
crystal field splitting
20-29-02UN
Title
Electronic transitions in crystal field splitting
Caption
The absorption spectra of different complexes indicate that the size of the crystal field splitting depends on the nature of the ligands.
Notes
The stronger the interaction between the ligand and a metal ion, the greater the crystal field splitting, D, and the higher the energy (and the lower the wavelength) of light absorbed by the complex.
Keywords
crystal field splitting
20-29-03UN
Title
The spectrochemical series
Caption
In general, the crystal field splitting increases as the ligand varies in the following order, known as the spectrochemical series.
Notes
The strong-field ligands CN-and CO are toxic to humans because of their strong interactions with iron in cytochrome oxidase and hemoglobin, respectively.
Keywords
spectrochemical series
20-29-04UN
Title
High spin versus low spin complexes
Caption
Crystal field theory accounts for the magnetic properties of complexes as well as for their color. Complexes with weak-field ligands are high-spin, while complexes with strong-field ligands are low-spin.
Notes
Crystal field theory correlates the relationship between weak-and strong-field ligands with high-and low-spin complexes, respectively.
Keywords
crystal field theory
20-29-05UN
Title
Worked Example 20.11
Caption
The energy level diagrams for the three complexes of Example 20.11.
Notes
Worked Example 20.11
Keywords
crystal field theory
20-30
Title
Tetrahedral and square planar complexes
Caption
Figure 20.30 Energies of the d orbitals in tetrahedral and square planar complexes relative to their energy in the free metal ion. The crystal field splitting energy D is small in tetrahedral complexes but much larger in square planar complexes.
Notes
Almost all tetrahedral complexes are high-spin, and square planar complexes are low-spin. Octahedral complexes can be either low-spin or high-spin.
Keywords
crystal field splitting
20-30-01
Title
Structures for Worked Example 20.12
Caption
Ball-and-stick models of iron(III) tetrachloride and platinum(II) tetrachloride.
Notes
Structures of iron(III) tetrachloride and platinum(II) tetrachloride for Worked Example 20.12
Keywords
crystal field theory
20-30-02UN
Title
Energy diagrams for Worked Example 20.12
Caption
Energy-level diagrams for iron(III) tetrachloride (tetrahedral, high-spin) and platinum(II) tetrachloride (square planar, low-spin).
Notes
Worked Example 20.12
Keywords
crystal field theory
20-30-030UN
Title
Key Concept Summary
Caption
Transition elements and coordination chemistry key concept summary.
Notes
Key Concept Summary for Chapter 20
Keywords
key concept, summary
20-30-05UN
Title
Key Concept Problem 20.19
Caption
What is the general trend in the following properties from left to right across the first transition series? Explain each trend.
Notes
Key Concept Problem 20.19
Keywords
key concept, transition elements, periodicity
20-30-06UN
Title
Key Concept Problem 20.20
Caption
Classify the following ligands as monodentate, bidentate, or tridentate. Which can form chelate rings?
Notes
Key Concept Problem 20.20
Keywords
key concept, ligands
20-30-07UN
Title
Key Concept Problem 20.22
Caption
Consider the following isomers of [Cr(NH3)2Cl4]--.
Notes
Key Concept Problem 20.22
Keywords
isomers, enantiomers
20-30-08UN
Title
Key Concept Problem 20.23
Caption
Consider the following ethylenediamine complexes:
Notes
Key Concept Problem 20.23
Keywords
key concept, chirality
20-30-10UN
Title
Key Concept Problem 20.25
Caption
Imagine two complexes, one tetrahedral and one square planar, in which the central atom is bonded to four different ligands (shown here in four different colors). Is either complex chiral? Explain.
Notes
Key Concept Problem 20.25
Keywords
key concept, chirality
20-TB01
Title
Table 20.1 Selected Properties of First-Series Transition Elements
Caption
Notes
Keywords
20-TB02
Title
Table 20.2 Standard Potentials for Oxidation of First-Series Transition Metals
Caption
Notes
Keywords
20-TB03
Title
Table 20.3 Chromium Species in Common Oxidation States
Caption
Notes
Keywords
20-TB04
Title
Table 20.4 Examples of Complexes with Various Coordination Numbers
Caption
Notes
Keywords
20-TB05
Title
Table 20.5 Names of Some Common Ligands
Caption
Notes
Keywords
20-TB06
Title
Table 20.6 Names of Some Common Metallate Anions
Caption
Notes
Keywords
20-TB07
Title
Table 20.7 Hybrid Orbitals for Common Coordination Geometries
Caption
Notes
Keywords

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