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alevel chem year 2 > Transition metals > Flashcards

Transition metals Flashcards

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1
Q

What are D block elements

A

Elements found in the middle of the periodic table

Most are known as transition elements

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2
Q

Electron configuration for chroniuM?

A

Has one electron in each orbital of the 3d subshell and one is 4s

Adds stability

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3
Q

Copper electron configuration

A

FULL 3d subshell, and 1 electron in 4s

Adds stability

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4
Q

How to form ions- TM

A

S electrons are removed first

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5
Q

What is the definition of a TM

A

D block elements that have an ion with an incomplete d-sub shell

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6
Q

What are the 2 exceptions of d block elements that are not transition metals

A

Scandium and zinc

DON’T form stable ions with incomplete d sub shells

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7
Q

Why is scandium not a transition metal?

A

Only forms one ion- Sc3+ , which has an empty d subshell

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8
Q

why is Zinc not a transition metal?

A

forms one ion - Zn 2+ , whcih has a full d subshell. When is becomes 2+, it just looses 4s so D continues to be full

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9
Q

3 key properties of TM metals and their compounds

A

Form compounds where the TE has a different oxidation sate

Form colored compounds

Elements and compounds can act as catalysts

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10
Q

Different oxidation states -why?

A

Compounds with more than one oxidation state e.g. iron forms 2 chlorines - iron 2 and iron 3 chloride

The elements show variable oxidation states because the energy levels of 4s and 3d subshells are very close to one another, so different numbers of electrons can be gained or lost using similar amounts of energy

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11
Q

The trend in number of oxidation states ACROSS the Tm series

A

Increases to manganese, then decreases

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12
Q

Formation of coloured compounds?

A

When mix an aqeuous solution of TM ions with aqueous sodium hydroxide or aqueous ammonia you get a coloured hydroxide precipitate

In aqueous solutions, TM metals take on the form [M(h20)]6 n +

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13
Q

TM as good catalysts

A
  • TM and their compounds make good catalysts because they can change oxidation states by gaining or losing electrons within their d orbitals, and then bind with reactants to form intermediates as part of a reaction pathway that has a lower activation energy
  • Can therefore transfer electrons to speed up reactions

Good at absorbing substances onto their surfaces to lower the AE and providing a surface for the reaction to take plpace - use d orbitals to do this

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14
Q

Catlayst examples - haber and contact process

A

HABER- Iron used, NH3+ 3H2– 2NH3

CONTACT - Vanadium oxide – SO2+1/2 o2 – So3

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15
Q

Complex ion

A

A metal ion surrounded by coordinately bonded ligands

One or more molecules or negatively charged ions bond to central metal ion

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16
Q

Ligand

A

A molecules or ion that donates a pair of electrons to central metal ion to a coordinate covalent bond

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17
Q

Dative/coordinate covalent bond

A

Special kind of covalent bond, formed when one of the bonded atoms provides both of the electrons fro the shared pair

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18
Q

Coordination number

A

Indicates number of coordinate bonds attached to the central metal ion

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19
Q

How do you write formula for complex ion

A

Square brackets

Metal then ligand with number of ligands

Overall charge outside

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20
Q

Monodentate ligand

A

Have one pair able to donate to central metal ion - availiable for bonding

e.g. water

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21
Q

Cyanide and ammonia charge

A

-1 and 0

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22
Q

Bidentate ligands

A

Some ligands can donate 2 lone pairs of electrons to the central metal ion, forming 2 coordinate bonds

E.g. 1,2 diaminoethane- ‘en’
In en

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23
Q

EN

A

1,2 diaminoethane

Each N atom donates a pair of electrons to teh central metal ion forming a coordinate bond

:Nh2h2ch2nh2:

24
Q

Copper with en

A

[Co(Nh2CH2CH2NH2)3]3+

Oxidation number of co is 3+

Coordination number is 6 because there are 3 En’s and each ligand forms 2 coordinate bonds

25
Q

shapes of complex ions- 4 coordinate shapes

A

Tetrahedral or square planar

26
Q

Tetrahedral shape

A

bond angle of 109.5

e.g. Cocl4 2- or CuCl4 2-

REMEMBER THE BRACKETS and charge

27
Q

Square planar

A

90 degrees
occurs in complex ions of transition metals with 8-d electrons in the highest energy d subshell
e.g. platnium and gold
[Pt(NH3)4]2+

28
Q

6 coordinate complex

A

octahedral

e.g. [Cu(h2o)6]2+ or [Fe(h20)6]3+

29
Q

what is stereoisomers

A

Same structural formula but different arrangement of the atoms

CIS TRANS
OPTICAL

30
Q

When is stereoisomerism shown

A

CIS TRANS - 4 coordinate and 6 coordinate containing 2 different monodentate ligands

6 coordinate complexes containg monodentate and bidentate can show BOTH optical and cis trans

Also 6 coordinator that can 3 bidentate show opitcal

31
Q

Cis trans isomerism

A

CIS on same

Trans on opposite side

32
Q

e.g. of a sqaure planar and octrahedral that shows cis trans?

A

Pt(Nh3)2cl2

[Cu(Nh3)4(H20)2]2+

33
Q

CAN tm metals be toxic

A

yes

34
Q

optical isomerism ? and example

A

Only includes octahedral complexes contain 2 or more bidentate ligands

Entantiomers are non superimposable mirror images of each other
[Ni(NH2CH2CH2NH2)3]2+

35
Q

Cis platin

A

A complex of platinum(II) witt 2 chloride ions and 2 ammonia

SQUARE PLANAR

Anti-cancer drug

chloride ligands easy to displace, so platin looses and bonds to 2 nitrogen atoms on DNA inside cancerous cell

Block on its DNA prevents cell from reproducing,s o dies

BUT also prevents normal cells from reproducing - including the blood which can suppress immune system

36
Q

What is ligand subsitution

A

When one ligand in a complex ion is replaced by another

37
Q

AQUEOUS copper 2 ions-

A

When copper 2 sulfate is dissolved in h2o
Pale blue
[Cu(h2o)6]2+

38
Q

Aqueous copper 2 ions with ammonia

A

pale blue preciptate of Cu(OH2) forms then to darker blue when the precipitate dissolves in excess ammonia

[Cu(h2o)6] 2+ + 4Nh3 — [Cu(nh3)4(h20)2] 2+ + 4h2o

39
Q

Aqeous copper 2 ions with chloride ions

A

Yellow solution forms
6 waters replaced with 4 chlorides ( chloride ligands larger)
Tetrahedral shape , reversible

Cu(H2O)6]2+ (aq) + 4Cl (aq)== [CuCl4]2- (aq) + 6H20 (l)

40
Q

Forming chromium(III) ions - 2 ways

A

chromium(III) potassium sulfate/chrome alum KCr(So4)212(h2o) is dissolved in water , [Cr(h2o)6]3+ is formed, a PALE PURPLE violet solution

When chronimium(iii) sulfate is dissolved in water, a green solution containing chronium(III) is formed. {Cr(H20)5SO4]+

41
Q

Chromium(III) in ammonia

A

[Cr(h2o)6]3+ , INITIALLY the drop wise ammonia formed Cr(OH)3, then it dissolves in the excess ammonia to form [Cr(NH3)6]3+, purple

Cr(h2o)6]3+ (aq) + 6NH3 —- [Cr(NH3)6]3+ + 6H20

42
Q

Ligand substitution- haemoglobin

A

4 protein chains held together by weak inter molecular forces, each chain has a haem molecule within its structure ( fe2+)

Oxygen can bind but SO CAN CO- more strongly than oxygen, forming carboxyhaemoglobin
Irreversible

43
Q

What is a precipitation reaction?

A

Occurs when 2 aqueous solutions containing ions react to form an insoluble ionic solid ( precipitate)

44
Q

Cu2+ in NaOH

A

Cu(OH)2 precipitate
BLue
Insoluble in excess

45
Q

Fe2+ in NaOH

A

Fe(OH)2 precipitate
Pale green— green
Insoluble in excess

Turns bronw on surface as oxidised to iron(III)

46
Q

Fe3+ in NaOH

A

Fe(OH)3 precipitate

Pale yellow— orange brown

INSOLUBLE in excess

47
Q

Mn2+ in NaOH

A

Pale pink — brown
Mn(OH) 2

Insoluble in excess

48
Q

Cr3+ in NaOH

A

Violet — grey green
Cr(OH)3
Precipitate soluble in excess – forming DARK GREEN = Cr(OH3) + 3OH- – [Cr(OH)6]3-

49
Q

which precipitates react with an excess of ammonia and what are their colours

A

Cu(OH) 2 is a blue precipitation dissolving to form a deep blue solution of [Cu(NH3)4(h2o)2]2+

Cr(OH)3 is a green precipitate which dissolves to form [cr(NH3)6]3+ which is a purple solution

50
Q

How do Fe2+, 3+ and Mn2+ react with ammonia

A

SAME way as sodium hydroxide

NOT further reaction with aqueous ammonia

51
Q

Oxidation of iron 2 to iron 3

A

MnO4- reduced to Mn2+
Iron 2 oxidised to iron 3
purple mn04 goes to colourised

52
Q

Reduction of iron 3 to iron 2

A

Fe3+ with iodide ions, orange brown fe3+ reduced to pale green fe2+

Iodide form iodine = brown

53
Q

Reduction of Cr2o72- to cr3+

A

Aqeuous cr2o7 2- orange
chromium 111 are green
Cr3+ - orange to green

Excess of zinc- chromium reduced to chromium 11 , pale blue

54
Q

Cr3+ oxdised to cr04-

A

using h2o2

55
Q

Reduction of Cu2+ to Cu+

A

When aqueous Cu2+ react with excess iodide ions, I- is oxidised to BROWN I2 and Cu2+ goes to I+
Pale blue — white precipitate of CuI and brown

56
Q

DISPROPORTIATION

with cu2o

A

When Cu20 ( solid copper 1 oxide) reacts with hot dilute sulfuric acid, a brown precipitate of copper is formed and a blue solution of copper 11 sulfate
CU+ is oxidized and reduced
Cu2o+ + h2so4—- Cu + CuSO4 + h20

57
Q

testing for ammonium ions

A

NH4+ – When heated with hydroxide ions, reacts to produce ammonia gas ( NH3)
To test for the ammonium ion, NaOH is heated with the solution, if ammonia is evolved, damp red pH indicator paper will turn blue

alevel chem year 2 (7 decks)

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