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year 13 chemistry > 5.3.1 - Transition Metals > Flashcards

5.3.1 - Transition Metals Flashcards

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1
Q

‘d’ block element def

A

Highest energy electron is in a ‘d’ orbital

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2
Q

Transition element def

A

Element forms a stable ion with an incomplete d-subshell

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3
Q

Properties of transition metals

A
  • Contain metallic bonding
  • Form giant metallic lattices
  • Form coloured compounds
  • Variable oxidation states/numbers
  • Used as catalysts due to variable oxidation state
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4
Q

Properties of metals

A
  • Generally unreactive/inert
  • Form coloured compounds
  • Form a giant metallic lattice
  • Good conductors of heat
  • Good conductors of electricity
  • More on photos
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5
Q

From what shell are electrons lost from first to form a positive ion in transition metals?

A

Lost from the 4s shell first before the 3d shell

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6
Q

Which transition metals have different electron shell configuration properties?
Why?
(4th and 6th transition metals - why?)

A
  • Chromium and Copper
  • (4th and 6th transition metals)
  • Chromium- 4s contains one electron and 3d orbitals all only contain one electron
  • Copper - all 3D orbitals are full, but the 4s only has one electron
  • This is because these configs are thought to reduce electron repulsion = more stable
  • So element is more stable
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7
Q

Complex ion def

A

A metal ion bonded to one or more ligands by coordinate bonds (dative covalent bonds)

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8
Q

Ligand def

A

A molecule or ion that can donate a pair of electrons to the transition metal ion to form a coordinate bond.

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9
Q

Coordination number def

A

Total number of coordinate bonds formed in the complex ion

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10
Q

Monodentate ligand def

A
  • A ligand that is able to donate one pair of electrons to a central metal ion
  • Only one atom in molecule/ion will donate the lone pair into the metal
  • can only form one coordinate bond with the central metal ion
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11
Q

Bidentate ligand def

A
  • A ligand that can donate two pairs of electrons to the central metal ion
  • Two atoms in the molecule/ion that donate the lone pair to the metal
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12
Q

Three shapes that complex ions can take

Why?

A

Tetrahedral - many ions have a coordinate number of 4
Gives rise to 4BPs
Square Planar - coordinate number of 4
Has 4BPs in corners of a square
Octahedral - many ions have a coordinate number of 6
Gives rise to 6BPs

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13
Q

Bond angles of each complex ion shape

A

Tetrahedral - 109.5 Degrees
Square Planar - 90 Degrees
Octahedral - 90 Degrees

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14
Q

Can complex ions display stereoisomerism?

A

Yes

- cis/trans and optical

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15
Q

What types of stereoisomers can complex ions form?

A

Cis-trans isomerism

Optical isomerism

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16
Q

Examples of monodentate ligands

A

-Water
-Ammonia
-Chloride
-
-

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17
Q

Examples of bidentate ligands

A
  • 1, 2-diaminoethane

- ethanedioate ion (oxalate ion)

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18
Q

Formula of cisplatin

Common shape of cisplatin

A
  • Pt(NH3)2Cl2

- Square planar

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19
Q

Stereoisomer def

A

Same structural formula but a different arrangement of the atoms in space

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20
Q

Type of isomer that can form in square planar shape with 4 coordinate complexes

A

Cis-trans isomerism

21
Q

Type of isomerism that can occur in an octahedral shape molecule with 6 coordinate complexes

A

Cis-trans isomerism

Optical isomerism

22
Q

Optical isomerism def

A
  • Two compounds which contain the same number and kinds of atoms, and bonds, and different spatial arrangements of the atoms
  • But which have non-superimposable mirror images.
  • Each non-superimposable mirror image structure is called an enantiomer.
  • a type of stereoisomerism
23
Q

How to differentiate between cis and trans isomerism in six coordinate complexes

A

Cis:
-Chosen groups are on the same side

Trans:
-Chosen groups are on opposite sides

24
Q

Can stereoisomerism occur in tetrahedral shapes

A

Yes - optical isomerism

Octahedral and tetrahedral show optical, but not square planar

25
Q

Optical isomerism def

A

Optical isomers are two compounds which contain the same number and kinds of atoms, and bonds, and different spatial arrangements of the atoms, but which have non-superimposable mirror images.
Each non-superimposable mirror image structure is called an enantiomer.

26
Q

Ligand substitution def

A

A reaction in which one ligand in a complex ion is replaced by another ligand

27
Q

Reaction of aqueous copper(II) ions when dissolved in water

A
  • When copper(II) sulfate is dissolved in water:

- Colour change from pale blue complex ion, [Cu(H20)6]2+ is formed in aqueous solution

28
Q

Ligand substitution of aqueous copper(II) ions with ammonia

A
  • When excess aqueous ammonia is added to a solution containing [Cu(H20)6]2+
  • Colour change from pale blue solution to a dark blue solution
  • form [Cu(H2O)2(NH3)4]
29
Q

Ligand substitution of aqueous copper(II) ions with ammonia experiment and observations

A
  • Add reagent(ammonia) drop-wise go solution under test
  • so that all observations are recorded
  • Two different reactions can be observed:
  • A pale blue precipitate of Cu(OH)2 is formed in first stage of the reaction
  • Cu(OH)2 precipitate then dissolves in excess ammonia to form a dark blue solution
30
Q

Ligand substitution of aqueous Copper(II) ions with chloride ions

A

-Conc. HCl can be used as a source of chloride ions
-When excess of conc. HCl is added to solution of [Cu(H2O)6]2+
-Pale blue solution changes colour to form a yellow solution
-Could form intermediate green solution if blue and yellow solution is mixed carefully together
-Six water ligands have been replaced with four chloride ligands
-Produces aqueous [Cu(Cl)4]2-
Equation: (= means reversible)
[Cu(H2O)6]2+(aq) + 4Cl- = [CuCl4]2-(aq) + 6H20(l)

31
Q

What changes occur in ligand substitution of aqueous copper(II) ions with chloride ions?

A

-Colour change: pale blue —> yellow
-Change in coordination no. : 6 —>4
Due to chloride ligands being larger in size than water ligands
Fewer chloride ions can fit around the central Cu2+ ion
-A change in shape: Octahedral —> Tetrahedral

32
Q

What remains the same in ligand substitution with chloride ions and copper ions?

A

-Oxidation state of copper remains +2

33
Q

Reactions with aqueous chromium(III) ions when dissolved in water
-Observations?

A
  • Chromium(III) potassium sulfate - KCr(SO4)2.12(H2O)
  • AKA Chrome Alum

-It is dissolved in water
-Complex ion [Cr(H2O)6]3+ is formed
This is a pale purple solution
- (or is it green solution)

-Oxidation state of chromium is 3+

34
Q

Chromium(III) sulfate dissolved in water reaction and observations

A
  • When chromium(III) sulfate is dissolved in water
  • A green solution containing chromium(III) is formed
  • This is a complex formed - [Cr(H2O)5(SO4)]+
  • One of the water ligands has been replaced by the sulfate ion(SO42-)

-Oxidation state of chromium is 3+

35
Q

Reaction of aqueous chromium ions with ammonia and observations
-ligand substitution reaction

-Reaction and observations when ammonia added drop-wise

A
  • [Cr(H2O)6]3+ takes part in a ligand substitution with an excess of aqueous ammonia forming the complex ion:
  • [Cr(NH3)6]3+
  • Added drop wise:
  • When Ammonia added drop-wise to chromium(III) solution, the reaction takes place in two distinct steps
  1. Initially a grey-green precipitate of Cr(OH)3, is formed
  2. Cr(OH)3 precipitate dissolved in excess ammonia to form a complex ion:
    - [Cr(NH3)6]3+

Equation is as follows:

36
Q

Why is Carbon Monoxide toxic to haemoglobin?

A
  • Haemoglobin contains Fe2+ groups that can carry oxygen
  • Carbon monoxide can also bind to Fe2+ groups on haemoglobin molecules
  • If breathed in, a ligand substitution reaction takes place
  • Oxygen in haemoglobin is replaced by carbon monoxide
  • To form carboxyhaemoglobin
  • Carbon monoxide is bonded more strongly than oxygen
  • Small conc. of CO in lungs prevents a large proportion of haemoglobin carrying O2
  • Bond is so strong that the process is irreversible
  • If conc. of carboxyhaemoglobin is too high, oxygen transport is prevented, leading to death
37
Q

How does a precipitation reaction occur?

A

When two aqueous solutions contains ions react together to form an insoluble ionic solid - this is the precipitate

38
Q

Precipitation reactions with NaOH

A

H

39
Q

Reactions of copper ions in NaOH and NH3

A

NaOH:
Blue sol. → Blue ppt.
Insoluble in excess NaOH
-Equation:

NH3:
Blue sol. —> blue ppt.
then deep blue sol.
Soluble in excess NH3
-Equation:
Forms [Cu(NH3)4(H2O)2)2+ (aq)
40
Q

Reactions and observations of Fe2+ ions with NaOH and NH3

Give equations for the reactions

A

NaOH:

Pale green sol. to green ppt.
Insoluble in excess NaOH
Ppt. turns brown - if exposed to air

NH3:

Pale green Sol. —> green ppt.
Insoluble in excess NH3

41
Q

Reactions of Fe3+ ions with NaOH and NH3

A

NaOH:

Pale yellow Sol. —> orange/brown Ppt.
• Insoluble in excess NaOH

NH3:

Pale yellow sol. —> orange/brown Ppt.
Insoluble in excess NH3

42
Q

Reactions of Mn2+ ions with NaOH and NH3

A

NaOH:

Pale pink sol. to light brown Ppt.
Insoluble in excess NaOH

NH3:

-Pale pink sol. —> light brown ppt.
• Insoluble in excess NH3

43
Q

Reactions of Cr2+ ions with NaOH and NH3

A

NaOH:

-Violet sol. —> grey ppt.
Soluble in excess NaOH to form green solution

NH3:

• Violet sol. —> grey Ppt .
° soluble in ✗ CS Ntlz
↳ dissolves to form purple sol.

44
Q 
Red blood cells contain haemoglobin.
Explain using ligand substitutions:
- how haemoglobin transports oxygen around the body
- why carbon monoxide is toxic
(3 Marks)
A
  • CO forms coordinate/dative bonds with Fe2+ central ion
  • O2 is replaced by carbon monoxide
  • CO forms stronger coordinate bonds than O2
  • CO bonds irreversibly
  • Prevents O2 from rebonding to haemoglobin ligand
45
Q

2 metals that are not transition metals

- why?

A
  • Zinc - full d-subshell
  • Scandium - no electrons in d-subshell
  • natural ions that form don’t contain incomplete d-subshells
46
Q

Examples of transition metals as catalysts

A

Haber process - Fe2+
Contact process - Vanadium Oxide
Hydrogenation of alkenes - nickel
Decomposition of hydrogen peroxide - Manganese oxide
Reaction of zinc with acids - Cu2+
Catalytic converters - platinum, palladium, rhodium etc.

47
Q

Transition elements ligand substitution table - learn or draw out and repeat

A
48
Q

Most d-block elements are classified as transition elements.
Explain why scandium and zinc are classified as d-block elements but are not also transition elements.
Your explanations should include full electron configurations.
(4 Marks)

A

Transition elements are elements that form a stable ion with an incomplete d-sub shell

D-block element def - an element with its highest energy electron on a d-sub shell

e- configurations of stable ions:
Zn2+ -
Sc3+ -

Sc3+ loses all its 4s electrons and it’s all 3d electrons - empty 3d sub shell
Zn2+ loses all its 4s electrons, but contains a full 3d sub shell

year 13 chemistry (20 decks)

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