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Chem - A level (units 1 -10) > Developing metals - Unit 9 > Flashcards

Developing metals - Unit 9 Flashcards

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1
Q

Transition metals?

A

Metal that can form more than one stable ion with a partially full d-orbital

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2
Q

When writing an e- configuration, does D go before S

A

Yes

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3
Q

Anomalies for e- configuration of D-block metals + why?

A 
Cr = (Ar) 3d(5) 4s(1)
Cu = (Ar) 3d(10) 4 s (1)

less repulsion if e- are places singly in d-orbitals than if they were paired together in the s-orbital

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4
Q

e- configuration of Ar

A

1s(2)2s(2)2p(6)3s(2)3p(6)

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5
Q

How do the d-block metals differ?

A

As you go across each element has 1 more e- in the 3d sub shell

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6
Q

Rule to remember when writing e- configerations?

A

Put numbers in correct order

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7
Q

Rule to remember when drawing the e- configuration of ions of the d-block

A

4s shell loses e- first

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8
Q

e- configuration of Cr(3+)

A

(Ar) 3d(3)

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9
Q

Are Zn + Sc transition metals +why?

A

No

  • Sc only forms 3+ ion (behaves like group 3 metal) with no d-orbital
  • Zn only forms 2+ ion (behaves like group 2 metal) with full d-orbital
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10
Q

Why do transition metals have many oxidation states?

A

there’s a number of stable arrangements of d + s block e-

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11
Q

Overall equation for redox titration using potassium manganate?

A

5Fe(2+) + MnO4(-) + 8H(+) –> 5Fe(3+) + Mn(2+) + 4H2O

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12
Q

When is the end point of the titration?

A

When there’s a pink colour (when MnO4- in excess)

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13
Q

Purpose of redox titration?

A

find conc. Fe2+ ions

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14
Q

colour potassium manganate?

A

KMnO4(-) = purple

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15
Q

Features transition metals?

A

1 - Form coloured compounds
2 - Have variable oxidation states
3 - Are catalysts
4 - Form complex ions

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16
Q

colour Fe2+ vs Fe3+ ions in sol.

A

Fe2+ = green

Fe3+ brown

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17
Q

Colour V2+, V3+, V4+, V5+ in sol.

A 
V2+ = lilac 
V3+ = green
V4+ = blue
V5+ = yellow
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18
Q

How do transition metals act as catalysts?

A
  • They have variable oxidation states
  • They have vacant d -orbitals
  • Therefore can accept e- to from dative covalent bonds
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19
Q

Heterogeneous catalysis of transition metals?

A

1 - use e- in partially full d orbital to form weak bonds to reactants on metal surface
2 - once the reaction has occurred, the bonds break releasing products

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20
Q

Homogeneous catalysis of transition metals?

A

1 - transition metal forms intermediate compound with reactant
2 - intermediate breaks down to form product

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21
Q

why are transition metals effective catalysts in redox reactions?

A

1 - They can move from one oxidation state to another

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22
Q

states in heterogenous catalyst transition metals?

A

Transition metal - solid

Reactant - gas/liquid

23
Q

states in homogenous catalyst transition metals?

A

both in aqueous

24
Q

What are the things that control the splitting of d-orbitals?

A

1 - The metal
2 - It’s Oxidation state
3 - Number and type ligand
4 - Shape of complex

25
Q

Colorimetry?

A

1 - Zero with a distilled water

26
Q

Colour of Fe(2+) , Fe (3+), Cu+, Cu(2+) in aq sol.

A
  • Fe (2+) = green
  • Fe (3+) = orange/brown
  • (Cu (+) = no colour - unstable in aq sol.
  • Cu (2+) = blue
27
Q

Why do are trasiiton metal complexex coloured?

A

1 - Ligands cause d-orbital splits so some d-orbitals higher in E than others
2 - This creates smaller E gap
3 - Therefore allows e
- to absorb lower freq. light in visible region
4 - therefore, e- moves to higher e level, emitting light

28
Q

What ia a bidentet liagand?

A

Soemthing that can form 2 dative covalent bonds to a metal ion

29
Q

What is a bidentate ligand?

A

Something that can form 2 dative covalent bonds to a metal ion

30
Q

monodentate

A

Something that can form 1 dative covalent bonds to a metal ion

31
Q

What does the colour of a trnsiiton metal complex depend on?

A

1 - no. d-orbital e - ion metal ion
2 - arrangemnt liganda affects plittign d orbital
3 - nature of ligand
4 - no. ligands

32
Q

potential difference?

A

A measure of how much electrode is tending to release or accept e-

33
Q

purpose salt bridge?

A

the ions carry the contact so there is an electrical current but the two solutions don’t mix

34
Q

conditions for electrochemical cell?

A

298 k

1 moldm-3

35
Q

Why is Pt electrode used?

A

Unreactive

36
Q

When is Pt used?

A

When half equations doesn’t involve metal but ions e.g Fe3+ + e- –> Fe(2+)

37
Q

What does it mean if E cell is pos vs neg?

A 
\+ = reaction feasible 
- = reaction can't occur at standard cond.
38
Q

If E cell is pos why my the reaction still not occur?

A
  • only tells you whether reaction is possible
  • not rate
  • therefore in reality reaction may be so slow that no change is observed
39
Q

Why could you do if E cell neg?

A

change conditions as this will change pd values

40
Q

Why Fe rusts?

A

When it rusts it forms layer Fe2O3xH200
This is no protective
Therefore layers beneath also corrode

41
Q

equation for rusting Fe?

A

Fe2+ + 2e- –> Fe
1/2 O2 + H2O + 2e- –> 2OH-

1/2 O2 + Fe + H2O –> Fe2+ + 2OH-

Fe2+ + 2OH- –> Fe (OH)2
+ O2(aq)
Fe2O3.xh20

42
Q

Sacrificial protection

A
  • More electroneg metal is oxidised
  • shifts it’s equilibrium to left
  • Therefore fe equilibrium shifts to right, preventing prod Fe2+
43
Q

Protecting against rust?

A

1 - layer paint, plastic film
2 - protective Zinc oxide layer. even if scratched Fe not rusted as Zinc more electronegative
3 - Supply e- to the metal from electrical source
4 - connect neg terminal battery to metal, therefore cathode. e- flow anode –> cathode

44
Q

Why Al, Zn, and Cr don’t rust?

A

form protective oxide layer

45
Q

What is a complex?

A
  • pos metal atom/ion surrounded by neg ions with lone pair e-, ligands
46
Q

Bonds in complex?

A
  • e- pair from ligand shared with metal ion forming datice covalnet bonds
47
Q

Coordination no.?

A

no. dative covalent bonds between ligand and central ion.

48
Q

shape complexes with coordination no. 6, 4,2?

A

6 - octahedral
4 - tetrahedral / square planar
2 - linear

49
Q

How can complexes have irregular shapes?

A

If bonding between betwen some ligands and cnetral ion more strogn than othere

50
Q

Polydente ligands?

A

ligands that can bdond more than once to a metal ion through more than one atom

51
Q

Example of ligand substitution?

A

1 - conc. HCl + (Cu(H2O)6)2+ (aq)
2 - Cl- displace water ligands
3 - (CuCl4))2-
4 - blue –> yellow

1 - conc. NH3(aq) + (Cu(H2O)6)2+ (aq)
2 - NH3 dispale water logands
3 - (Cu(NH3)4(H2O)2)2+ + 4H2O

52
Q

When does ligand substitution occur?

A

If teh new complex more stabel than the pervious complex

53
Q

What does the stabiloty of a complex depend on?

A

It’s ligands

Chem - A level (units 1 -10) (14 decks)

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