Chapter 24: Transition Elements Flashcards

1
Q

What are the d-block elements?

A
  • The elements located between groups 2 and 3 in the periodic table
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2
Q

Which d-block elements’ electronic configuration does not fit the trend?

A
  • Chromium and copper
  • Both have 1 electron in their 4s sub-shell instead of 2 so that they can either have a half-full or fully filled 3d sub-shell, as this is more stable
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3
Q

What are the transition elements? Required.

A
  • The d-block elements that form at least one ion with a partially filled d sub-shell
  • This means that scandium and zinc, for example, aren’t transition elements
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4
Q

Which ions do scandium and zinc form, and why?

A
  • Sc^3+ (loses both 4s electrons and one 3d electron)
  • Zn^2+ (loses both 4s electrons, so all 10 3d electrons remain)
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5
Q

What are 3 properties of transition metals?

A
  • The elements can each have multiple oxidation states when forming compounds
  • They can form coloured ions
  • The elements and their compounds can act as catalysts
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6
Q

Give 2 possible oxidation states and corresponding colours of the solutions of 2 transition metals.

A
  • Chromium:
  • chromium (VI) is orange
  • chromium (III) is green
  • Iron:
  • iron (II) is pale green
  • iron (III) is pale yellow
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7
Q

How do transition metals act as catalysts?

A
  • They provide an alternative reaction pathway with lower activation energy
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8
Q

Give an example of a transition metal acting as a catalyst.

A
  • Nickel in the hydrogenation of alkenes
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9
Q

What is a complex ion?

A
  • Complex ions are formed when one or more molecules or negatively charged ions (ligands) bond to a central metal ion
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10
Q

What is a ligand? Required. What property must all ligands have as a result?

A
  • A molecule or ion that donates a lone pair of electrons to a central metal ion to form a dative covalent/ coordinate bond
  • Lone pair
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11
Q

What is the coordination number?

A
  • The number of coordinate bonds attached to the central metal ion
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12
Q

How are the formulae of complex ions written? Give an example.

A
  • There are square brackets surrounding the complex ion, with the overall charge written on the outside
  • Inside the square brackets the metal ion is written first, but without its charge
  • The ligand(s) come next:
  • if its a molecule, its written inside regular brackets, followed by the number of times it is present in the complex ion
  • if it is a single element (such as a chloride ion) it is written without brackets and its charge
  • [Cr(H2O)6]3+
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13
Q

How can the charge on the central metal ion be found when given the charge and formula of the complex ion?

A
  • Subtract the overall charge of the ligands from the charge of the complex ion
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14
Q

What do co-ordination numbers determine?

A
  • The shape of the complex ion
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15
Q

What shape does a coordination number of 6 lead to? What is the bond angle?

A
  • Octahedral
  • 90°
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16
Q

What shape does a coordination number of 4 usually lead to? What is the bond angle? What condition leads to an exception?

A
  • Tetrahedral
  • 109.5°
  • If the transition metal ion has 8d electrons
17
Q

What is the alternative shape a coordination number of 4 can cause? What is the bond angle? Give 3 examples of ions that cause this.

A
  • Square planar
  • 90°
  • Platinum (II), palladium (II) and gold (III)
18
Q

How are complex ions with a square planar shape drawn?

A
  • The ligands are arranged as if in the corners of a rectangle
  • The top 2 have dashed wedges
  • The bottom 2 have plain wedges
19
Q

What do all drawings of complex ions need to show?

A
  • The metal ion needs to be bonded to the atom with the lone pair
  • Draw these in first
20
Q

What 2 categories can ligands come under, and what does each mean?

A
  • Monodentate: a ligand that can donate one pair of electrons to a central metal ion
  • Bidentate: a ligand that can donate 2 electron pairs to a central metal ion
21
Q

What are the 2 most common bidentate ligands?

A
  • 1,2-diaminoethane/ ‘en’
  • (CH2NH2)2
  • Ethanedioate ion
  • (COO-)2
22
Q

How are complex ions with bidentate ligands drawn?

A
  • You draw the central metal ion and the bonds around it in the regular way
  • Each bidentate ligand makes 2 adjacent coordinate bonds with the central metal ion
23
Q

What types of stereoisomerism can complex ions display?

A
  • Cis-trans isomerism
  • Optical isomerism
24
Q

Complex ions with what coordination number can display cis-trans isomerism?

25
Q

What causes a 4-coordinate complex ion to have cis-trans isomerism?

A
  • It has to be square planar
  • There are 2 pairs of identical ligands
26
Q

In square planar complex ions with cis-trans isomerism, which would be the cis isomer and which would be the trans isomer? Include the bond angles.

A
  • If 2 of the identical ligands are adjacent to each other, this would be the cis isomer
  • 90°
  • If the 2 identical ligands are opposite each other (across the metal ion from each other, not adjacent)
  • 180°
27
Q

What causes a 6-coordinate complex ion to have cis-trans isomerism?

A
  • There are 2 identical monodentate ligands, and 4 monodentate ligands of another type
  • There are 2 identical monodentate ligands, and 2 bidentate ligands
28
Q

In octahedral complex ions with monodentate ligands that display cis-trans isomerism, which would be the cis isomer and which would be the trans isomer? Include the bond angles.

A
  • The trans isomer would be where the 2 identical ligands are opposite (2 other monodentate ligands separate them)
  • 180°
  • The cis isomer would be where the 2 identical ligands are either adjacent or one monodentate ligand apart
  • 90°
29
Q

Which complex ions can display optical isomerism?

A
  • Octahedral ions with 2 or more bidentate ligands
  • However, only the cis isomers display optical isomerism if there are 2 bidentate ligands (trans isomers’ mirror image would be the same)
30
Q

How is cis-trans isomerism in complex ions applied in real life? Give the name and formula of the complex ion.

A
  • Cis-platin is an anti-cancer drug
  • Pt (NH3)2 (Cl)2
31
Q

How does cis-platin work?

A
  • It binds to DNA inside the cell and stops it from replicating