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OCR A A-Level Chemistry > Chapter 24 - Transition Elements > Flashcards

Chapter 24 - Transition Elements Flashcards

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1
Q

Which two elements don’t follow the typical electron figuration?

A

Chromium and copper

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2
Q

Why isn’t scandium classified as a transition metal?

A

A transition metal forms at least one ion with a partially filled d-orbital
Scandium forms Sc3+ by losing two 4S electrons and one 3D

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3
Q

Why isn’t zinc classified as a transition metal?

A

Zn2+ has a full d-orbital

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4
Q

Characteristics of transition metals

A

The element can have variable oxidation states
They form coloured compounds
Can act as catalysts

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5
Q

Which transition metal has the largest amount of oxidation states?

A

Manganese

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6
Q

What colour is iron (II)?

A

Pale green

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7
Q

What colour is iron (III)?

A

Yellow

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8
Q

What colour is Cr (III)?

A

Green

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9
Q

What colour is Cr (VI)?

A

Dark yellow

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10
Q

What catalyst is used in the Haber process?

A

Iron

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11
Q

What catalyst is used in the Contact process?

A

Vanadium oxide

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12
Q

What catalyst is used to hydrogenate vegetable fats?

A

Nickel

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13
Q

What catalyst is used to decompose hydrogen peroxide?

A

Manganese oxide

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14
Q

What are heterogenous catalysts?

A

The catalyst is in a different state to the reactants

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15
Q

What are homogenous catalysts?

A

The catalyst is in the same state as the reactants

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16
Q

When will a complex ion form?

A

When one or more molecules bond to a central atom

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17
Q

What is a ligand?

A

A molecule that donates a pair of atoms to a central molecule to form a dative covalent bond

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18
Q

What is the coordinate number?

A

The number of coordinate bonds attached to that atom

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19
Q

What is a monodentate ligand?

A

It is able to donate one pair of electrons to the central atom

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20
Q

What are bidentate ligands?

A

Able to donate two pairs of electrons to a central atom

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21
Q

What is the shape of a complex ion with a coordination number of 6?

A

Octahedral

22
Q

When will a complex ion form a tetrahedral shape?

A

When it has a coordination number of 4

23
Q

When will a complex ion exist as cis-trans isomers?

A

When octahedral complexes consist of four of one type of ligand and two of another type

24
Q

When will a complex ion form a square planar shape?

A

When it has a coordination number of 4 and the ion is of a transition metal

25
Q

When will optical isomerism occur?

A

Octahedral complexes containing 2+ bidentate ligands

26
Q

What is a ligand substitution reaction?

A

One ligand or complex ion is replaced by another

27
Q

What colour is the solution formed when copper (II) sulphate is dissolved in water?

A

Pale blue

28
Q

What happens when excess ammonia is added to [Cu(H2O)6]?

A

Four water ligands are replaced by four ammonia ligands
In the first stage of the reaction, pale blue Cu(OH)2 is formed
Cu(OH)2 dissolves to form a darker blue solution

29
Q

What happens when excess HCl is added to [Cu(H2O)6]?

A

Six water ligands are replaced by 4 chloride ligands

Pale blue solution changes yellow

30
Q

What complex ion is formed when chromium (II) potassium sulphate is dissolved in water?

A

[Cr(H2O)6]3+

31
Q

What colour is [Cr(H2O)6]?

A

Pale purple

32
Q

Which complex ion is formed when chromium (II) sulfate is dissolved in water?

A

[Cr(H2O)5 SO4]+

33
Q

Describe the reaction that occurs when ammonia is added to [Cr(H2O)6] 3+

A

Initially, grey-green Cr(OH)3 is formed

This dissolves in the ammonia to form [Cr(NH3)6]3+

34
Q

What happens when carbon monoxide is breathed in?

A

A ligand substitution reaction takes place - oxygen in oxyhemoglobin is replaced by carbon monoxide

35
Q

What is a precipitation reaction?

A

Two aqueous solutions form an insoluble ionic solid

36
Q

What is produced when Cu2+ reacts with NaOH?

A

Blue copper hydroxide is produced, which is insoluble in sodium hydroxide

37
Q

What is produced when Fe2+ reacts with NaOH?

A 
Green iron (II) is formed, which is insoluble in NaOH
Upon standing, the iron is oxidised to form iron (III)
38
Q

What is produced when Fe3+ reacts with NaOH?

A
  • Orange brown iron (III) hydroxide is formed

- Insoluble in NaOH

39
Q

What is produced when Mn2+ reacts with NaOH?

A

Light brown manganese hydroxide is formed, which is insoluble in NaOH

40
Q

What happens when Cr3+ reacts with NaOH?

A

Grey-green chromium hydroxide is formed, which is soluble in NaOH and forms a green solution

41
Q

What happens to Fe2+ when it is titrated?

A

Oxidised to Fe3+

42
Q

What colour are dichromate ions?

A

Orange

43
Q

How are dichromate ions changed into chromium ions?

A

Addition of zinc - Cr2O72- is reduced

44
Q

Equation for the oxidation of Cr3+ to CrO42-

A

3H2O2 + 2Cr3+ + 10OH- -> 2CrO42- + 8H2O

45
Q

What happens when I- reacts with Cu2+?

A

I- is oxidised to I2

Cu2+ is reduced to Cu+

46
Q

Equation for I- reacting with Cu2+

A

2Cu2+ +4I- ->2CuI + I2

47
Q

How to test for the ammonium ion?

A

NaOH is heated with the solution being analysed

If ammonia is present, litmus paper will turn red

48
Q

What is a ligand substitution reaction?

A

One ligand in a complex ion will be replaced by another

49
Q

What colour is the solution formed when copper (II) sulfate is dissolved in water?

A

Pale blue

50
Q

What happens when excess ammonia is added to a solution containing [Cu(H2O)6] and why?

A

The pale blue colour changes to a dark blue one

4 ammonia molecules have replaced 4 of the water molecules in the

51
Q

What happens when excess ammonia is added to a solution containing [Cu(H2O)6] and why?

A

The pale blue colour changes to a dark blue one

4 ammonia molecules have replaced 4 of the water molecules in the

52
Q

Which two elements don’t follow the typical electron figuration?

A

Chromium and copper

OCR A A-Level Chemistry (28 decks)

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