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A-Level Chemistry > Chapter 24 Complex Ions And Ligands > Flashcards

Chapter 24 Complex Ions And Ligands Flashcards

1
Q

What is the electron configuration for chromium?

A

3d5 4s1

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2
Q

What is the electron configuration for copper?

A

3d10 4s1

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3
Q

What is the explanation for the electron of chromium an copper being different?

A

Stability

A half-filled and fully-filled d sub-shell give additional stability to atoms of chromium and copper

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4
Q

What is lost before a 3d electron?

A

4s electron

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5
Q

What are transition elements?

A

D-block elements that form at least one ion with a partially filled d-orbital

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6
Q

What are scandium and zinc not classified as transition elements?

A

Zn2+ has a fully-filled d-orbital

Sc3+ have empty d-orbitals

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7
Q

What is a catalyst?

A

A substance that increases the rate of a reaction without itself changing

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8
Q

What are TWO examples of transition metals and their compounds being used in industry to catalyse reactions?

A

Hager process
N2 +3H2 2NH3
IRON CATALYST

Contact process
2SO2 +O2 2SO3
VANADIUM OXIDE CATALYST (V2O5)

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9
Q

What is a homogenous catalyst?

A

A catalyst that is in the same state as its reactants

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10
Q

What is a heterogenous catalyst?

A

A catalyst that is in a different state to its reactants

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11
Q

Are complex ions restricted to d-block elements?

A

No

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12
Q

What is a complex ion?

A

One or more molecules / negatively charged ions bonded to a central metal ion

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13
Q

What is ligand?

A

A molecule or ion that donates. a pair of electrons to a central metal ion to form a COORDINATE BOND or DATIVE COVALENT BOND

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14
Q

What is a dative covalent bond / coordinate bond?

A

A special kind of covalent bond where one of the bonded atoms provide both of the electrons for the shared pair

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15
Q

What is coordination number?

A

Indicates the number of coordinate bonds attached to the central metal ion

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16
Q

Which monodentate ligand seems are neutral?

A

Water and ammonia (NH3)

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17
Q

What is the difference between a monodentate ligand and a bidentate ligand?

A

Monodentate ligand donates ONE electron pair to form ONE coordinate bond

Bidentate ligand donate TWO electron pairs to form TWO coordinate bonds

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18
Q

What are examples of two common bidentate ligands?

A

1,2-

Ethanedioate ion (oxalate ion)

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19
Q

What shape do six-coordinate complexes have?

A

Octahedral shape 90

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20
Q

What shape does four-coordinate complexes have?

A

Tetrahedral 109.5 and square planar 90

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21
Q

What are some complex ions for tetrahedral shapes?

A

Co and Cu

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22
Q

Where does a square planar shape occur?

A

A square planar shape occurs in complex ions of transition metals with 8 d-electrons in the highest energy d-sub-shell

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23
Q

Which metal ions fall into the square planar shape category?

A

Platinum 2

Palladium 2

Gold 3

24
Q

What is the most common complex?

A

Six-coordinate complexes (forming octahedral shapes)

25
What are the colours of the two cis-trans isomers of [Co(NH3)4Cl2]+?
Cis violet Trans green
26
What is another name for an optical isomer?
Enantiomer
27
What are optical isomers?
Non-superimposable mirror images of each other
28
What is a ligand substitution reaction?
Reaction in which one ligand in a complex ion is replaced by another ligand
29
What is the COMPLEX and COLOUR formed when copper sulfate dissolves in water?
PALE BLUE [Cu(H2O)6]2+
30
What happens when an EXCESS of AMMONIA is added to a solution containing [Cu(H2O)6]2+?
PALE BLUE -> DARK BLUE [Cu(H2O)6]2+ + 4NH3 -> [Cu(NH3)4(H2O)2]2+ + 4H2O
31
What are the SEPARATE steps involved in the reaction of EXCESS AMMONIA with [Cu(H2O)6]2+?
PALE BLUE SOLUTION -> PALE BLUE PRECIPITATE of Cu(OH)2 CU(OH2) precipitation then DISSOLVES in EXCESS AMMONIA to form a a DARK BLUE solution
32
What happens when EXCESS CONCENTRATED HCl is added to a solution of [Cu(H2O)6]2+?
PALE BLUE SOLUTION -> YELLOW SOLUTION -> BLUE SOLUTION with addition of WATER [Cu(H2O)6]2+ 4Cl- [CuCl4]2- + 6H2O
33
What happens when water is added to the yellow solution of [CuCl4]2-?
BLUE SOLUTION forms that is paler and more dilue
34
Why does an intermediate green solution form when excess concentrated HCl reacts with [Cu(H2O)6]2+?
It is a result of yellow solution mixing with blue solution as reaction proceeds
35
Why does the COORDINATION NUMBER of the COPPER complex ion change when excess concentrated HCl is added?
Chloride ions are larger than H2O ions so less can fit around central Cu2+ ion Results in change in coordination number and shape from OCTAHEDRAL to TETRAHEDRAL
36
What is the formula of chromium (III) potassium sulfate?
KCr(SO4)2.12(H2O)
37
What is chromium (III) potassium sulfate also known as?
Chrome alum
38
Which complex ion is formed when CHROMIUM (III) POTASSIUM SULFATE is dissolved in water?
[Cr(H2O)6]3+ VIOLET SOLUTION
39
Which complex ion is formed when CHROMIUM SULFATE is dissolved in water?
[Cr(H2O)5SO4]+ GREEN SOLUTION
40
What do both green and violet solutions of chromium contain?
Chromium (III) in +3 oxidation state
41
What are the properties of transition metals and their compounds?
Form compounds in which transition metal has different OXIDATION STATES Form COLOURED compounds Elements and their compounds can act as CATALYSTS
42
What happens (in spectate steps) when aqueous AMMONIA is added DROP-WISE to a a solution containing [Cr(H2O)6]3+?
Cr(OH)3 formed VIOLET -> GREY-GREEN PRECIPITATE Cr(OH)3 precipitate DISSOLVES in EXCESS AMMONIA to form complex ion [Cr(NH3)6]3+ PURPLE SOLUTION
43
How is blood carried around the body?
Presence of haemoglobin, iron-containing protein present in all blood cells
44
What is the structure of haemoglobin?
FOUR protein chains held together by weak intermolecular forces EACH protein chain has a HAEM molecule within its structure Central metal ion in haem group is Fe2+ which can bind to oxygen gas
45
What is the complex formed when carbon monoxide bonds to the Fe2+ ion in haemoglobin?
CO bonds to haemoglobin MORE STRONGLY than O2 in IRREVERSIBLE REACTION Too high concentrations of carboxyhamepglbin can lead to death
46
What is a PRECIPITATION REACTION?
Two aqueous solutions containing ions react together to form an insoluble ionic solid, called a precipitate
47
How does Cu2+ + NaOH react?
Cu2+ + 2OH- -> Cu(OH)2 BLUE SOLUTION -> BLUE PRECIPITATE INSOLUBLE IN EXCESS SODIUM NaOH
48
How does Fe2+ + NaOH react?
Fe2+ + 2OH- -> Fe(OH)2 PALE GREEN SOLUTION -> GREEN PRECIPITATE INSOLUBLE IN EXCESS NaOH In air: Turns BROWN at its SURFACE on standing in air as iron (II) is OXIDISED to iron (III) Fe(OH)2 -> Fe(OH3) GREEN PRECIPITATE -> ORANGE-BROWN PRECIPITATE
49
How does Fe3+ + NaOH react?
Fe3+ + 3OH- -> Fe(OH)3 PALE YELLOW SOLUTION -> ORANGE-BROWN PRECIPITATE INSOLUBLE IN EXCESS NaOH
50
How does Mn2+ + NaOH react?
Mn2+ + 2OH- -> Mn(OH)2 PALE PINK SOLUTION -> LIGHT BROWN PRECIPITATE Precipitate darkens on standing in air INSOLUBLE IN EXCESS NaOH
51
How does Cr3+ + NaOH react?
Fe3+ +3OH- —> Cr(OH)3 VIOLET SOLUTION —> GREY-GREEN PRECIPITATE Soluble in excess NaOH Cr(OH)3 + 3OH- —> [Cr(OH)6)]3- Grey-green precipitate —> Dark green solution
52
Which precipitates of which TWO central metal ions DO dissolve in excess ammonia?
Cu2+ and Cr2+
53
Which precipitated of which metal ions DO. OT dissolve in excess ammonia?
Fe2+, Fe3+ and Mn2+
54
What happens when Cu(OH)2 is DISSOLVED in EXCESS AMMONIA?
[Cu(NH3)4(H2O)2]2+ complex ion forms BLUE PRECIPITATE —> DEEP BLUE SOLUTION
55
What happens when Cr(OH)3 DISSOLVES in EXCESS AMMONIA?
[Cr(NH3)6]3+ GREEN PRECIPITATE —> PURPLE SOLUTION
56
What is a DISPROPORTIONATION reaction?
The dam element has been reduced and oxidised

A-Level Chemistry (13 decks)

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