5.3 Transition Elements (completed) Flashcards

1
Q

What is the definition of a transition element?

A

D-Block element that form one or more stable ions with partially filled d sub shells

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2
Q

What is different about the electronic configuration of chromium and copper?

A

They promote electrons from the 4s sub shell to the 3d sub shell in order to make it more stable

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3
Q

Why are zinc and scandium considered not transition metals?

A

They don’t form stable ions with an incomplete d sub shell

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4
Q

What colour are the two chromium ions you need to know?

A

Cr 3+ Green

Cr 6+ Orange

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5
Q

What colour are the two manganese ions you need to know?

A

Mn 2+ Pink

Mn 7+ Purple

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6
Q

What colour are the two iron ions you need to know?

A

Fe 2+ Green

Fe 3+ Orange

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7
Q

What colour is the copper ion you need to know?

A

Cu 2+ Blue

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8
Q

How do transistion metals catalyse reactions?

A

Adsorption – gases are pulled onto the surface of catalyst
Bonds weakening and reaction takes place
Desorption – products leave surface of catalyst

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9
Q

What do transition metal hydroxide tend to be?

A

Insoluble so a solid precipitate can form with a certain colour

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10
Q
What are the colours of the following hydroxide precipitates?
Cu 2+
Cr 3+
Fe 2+
Fe 3+
Mn 2+
A
Cu(OH)2   Light blue
Cr (OH)3   Dark green
Fe (OH)2   Dark Green
Fe (OH)3   Orange-brown 
Mn (OH)2   Brown
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11
Q

What is a complex ion?

A

A central metal ion surrounded by ligands

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12
Q

What are ligands?

A

Species that can donate one more lone pairs of electrons to form dative bonds with a central ion

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13
Q

What is the coordination number?

A

The number of dative bond is formed in a complex ion

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14
Q

Name three ligands?

A

Water
Ammonia
Cl-

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15
Q

What is the definition of monodentate, bi dentate and multidentate?

A
Can donate one lone pair
H2O NH3 Cl-
Can donate two lone pairs
NH2CH2CH2NH2 en
Can donate three or more lone pairs
EDTA4- (6 lone pairs)
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16
Q

What are the three structures of complex ions?

A

Tetrahedral – four bonding pairs 109.5°
Octahedral – six bonding pairs 90°
Square planar – four bonding pairs 90°

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17
Q

What is cisplatin?

A
[PtCl2(NH3)2]
Square planer
Two stereo isomers (cis, trans)
Cis used as an anti-cancer drug
Trans isomer has no anti-cancer properties
18
Q

What are optical isomers?

A

Isomers that a non-super imposible mirror images of each other

19
Q

Why is haemoglobin a complex ion?

A

In each haem group there four nitrogen atoms that form co ordinate bonds with Fe 2+ ion

20
Q

What is the ligand substitution of Chromium (III) with NaOH?

A

Purple Solution [Cr(H2O)6]3+

Add NaOH solution
Light Green Precipitate Cr(OH)3 firmed

Add excess NaOH solution
Dark green solution [Cr(OH)6]3-

21
Q

Why does [Cr(H2O)6]3+ not often appear as a purple solution?

A

A tiny amount of impurity will turn the solution green

22
Q

What happens if you add excess ammonia to a Chromium (III) Hydroxide?

A

Light green precipitate → Purple Solution

[Cr(NH3)6]3+

23
Q

What is the ligand substitution of Copper (II) with HCl?

A

Blue solution [Cu(H2O)6]2+

Add excess concentrated HCl
Yellow solution [CuCl4]2-
(green initially)

Add excesss H2O returned to
Blue solution [Cu(H2O)6]2+

24
Q

What is the ligand substitution of Copper (II) with ammonia?

A

Light Blue solution [Cu(H2O)6]2+

Add excess concentrated NH3
Dark Blue solution [CuCl4]2-

Initially a small amount of a light blue precipitate of copper hydroxide but then in excess this dissolves

Add excesss H2O returned to
Light Blue solution [Cu(H2O)6]2+

25
Q

What is the colour change of the oxidation of Fe2+ and Cr2O7 2-?

A

Fe2+ → Fe3+
Light green → Red/Brown

Cr2O7 2- → Cr3+
Orange → Green

26
Q

What are the properties of transition metals?

A

Variable oxidation states
Form colour compounds
Can act as a catlyst
Form insoluble hydroxide precipitates

27
Q

What types of catalysts are transition metals?

A

Usually heterogenous catalysts
Catalyse reactions in a different phase to themselves
e.g. solid iron catalysing gaseous haber process

28
Q

What catalyses the Haber Process?

A

Iron

29
Q

How does oxygen and carbon monoxide bind to haemoglobin?

A

Oxygen binds reversibly to the Fe2+ ion in the haem group

Cyanide ions and carbon monoxide bind more strongly

30
Q

What is the colour change of the reduction of Cu 2+ ions?

A

Cu2+ → Cu+

Blue → Colourless

31
Q

Why is Cu + colourless?

A

It does not have an incomplete d sub shell

32
Q

What is the disproportionation of Cu +?

A

Cu+ → Cu(s) + Cu2+

33
Q

Explain using ligand substitutions how haemoglobin transports oxygen and why CO is toxic?

A

O2 forms dative bonds with iron
Ligand substitution occurs and O2 is replaced by H2O or CO2 when needed for transport
CO forms stronger bonds with iron than O2

34
Q

What is the colour of CoCl4 2- and how is it formed?

A

Dark blue

From CoCl2.6H2O(s) plus water and excess HCl

35
Q

What is the colour of CrO4 2- and how is it formed?

A

Oxidation of Cr3+ with hot alkaline H2O2

yellow

36
Q

What is the colour of Mn(OH)2 and how is it formed?

A

NaOH dropwise to [Mn(H2O)6]
2+ pale brown precipitate
From light pink solution

37
Q

What is the colour of [Fe(H2O)6] 2+ and how is it formed?

A

From FeSO4.7H2O(s)

pale green

38
Q

What is the colour of Fe(OH)2 (s) and how is it formed?

A

NaOH dropwise to Fe2+(aq)

dark green precipitate

39
Q

What is the colour of [Fe(H2O)6] 3+ and how is it formed?

A

From FeCl3.6H2O(s)

yellow

40
Q

What is the colour of Fe(OH)3 (s) and how is it formed?

A

NaOH dropwise to Fe3+(aq)

orange-brown precipitate

41
Q

What is the colour change of the titration of MnO4/Fe2+ to Mn2+/Fe3+?

A

purple (MnO4) to pale pink (Mn2+)

in titrations, so dilute that it is practically colourless

42
Q

What is the colour change of the titration of I/Fe3+ I2/Fe2+

A

orange brown (Fe3+) to brown (I2)