Chapter 23: Transition Metals and Coordination Compounds Flashcards Preview

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Flashcards in Chapter 23: Transition Metals and Coordination Compounds Deck (39)
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1

Properties of Transition Metals
- Size
- Ionization energy
- Electronegativity
- Oxidation states

- All have orbitals that can be involved with metallic bonding
- Little variation in size across a row
- 3rd transition row not larger
- Ionization energy: First ionization E of transition elements increases across; move down a group, third transition row has higher ionization energy
- Electronegativity: Increase across a row; increase down from first row (no further increase in 3rd or 4th)
- Exhibit variety of oxidation states

2

Lanthanide contraction

- Outer electron are held more tightly by nucleus and offset typical increase in size between periods

3

Transition Metal Electron Configurations

- Ground state e- for first two rows: ns^2(n-d)d^x
- 3/4 rows: ns^2(n-2)f^14(n-1)d^x

4

Complex ion

- Contains central metal ion bound to one or more ligans

5

Ligand

Lewis base (e- donor that forms bond with metal)

6

Coordination compound

Complex ion combines with one or more counter ions

7

Primary Valence

Oxidation state on central metal atom

8

Secondary valence

Number of molecules or ions bound to metal ions (this is the coordination number)

9

Coordinate covalent bond

- Bond formed by donation of pair of e- from ligand to empty orbital in metal

10

Monodenate

Ligand that only donates one e- pair to central metal

11

Bidenate

- Ligands that donate two pair of e-

12

Polydenate

- Ligand that donates more than two pairs of e-

13

Chelate

- Complex ion with bidenate or polydenate ligand; coordinating ligand is chelating agent

14

Common Ligand

- Water (H2O)
- Ammonia (NH3)
- Chloride ion
- Carbon monoxide
- Thiocyanite (SCN-)
- Oxalate ion
- Ethylenediamine (en)
- Ethylenediaminetetradacetate (Edia)

15

Coordination Numbers + Geometrics

- 2: Linear
- 4: Square planar or Tetrahedral
- 6: Octahedral

16

Structural Isomers

- Atoms connected to each other in different ways

17

Steroisomers

Atoms connected in same way; ligands have different spatial arrangement around metal atom

18

Coordination Isomer

- Structural
- Occur when coordinated ligands exchange places with uncoordinated counterion

19

Linkage isomers

- Structural
- Have ligands that coordinate to the metal in different orientations

20

- Geometric isomers

- Stereoisomerism
- Ligands bonding to the metal have different spatial arrangements

21

Cis-Trans Isomers

- Stereo/Geometric
- Compelx ions occur in square plans complexes of general formula MA2B2; or MA4B2
- Cis (same side), trans (opposite sides)

22

Fac-Mer

- Stereo/Geometric
- Octahedral complexes (MA3B3)
- Fac: Ligands on one side
- Mer: Ligands form an arc

23

Optical Isomers

- Nonsuperimposable mirror images of one another
- Chiral: Molecules ions that exhibit this quality
Enantiomers: Isomers that exhibit property of optical activity

24

Identifying and Drawing

1) Decide whether ligands are mono, bi, or polydenate.
2) Determine coordination number and geometry.
3) Draw
4) Rotate one 180˚, if it is non superimposable then it exhibits optical activity

25

Coordinate valence bond

- Overlap between completely filled atomic orbital and empty atomic orbital

26

Common Hybridization Schemes

- Linear (sp)
- Tetrahedral (sp3)
- Square planar (dsp2)
- Octahedral (d2sp3)

27

Crystal Field Theory (general definition)

- Bonding model for transition metal complexes that accounts for color and magnetism

28

Octahedral Complexes

- Form because attractions between e- on ligands/positive change on metal ion; e- on ligands also repel unhybridized metal d orbital

29

Strong-field complexes

- Splitting is large

30

Weak-field complexes

- Splitting is small