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Chemistry > F Block > Flashcards

F Block Flashcards

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1
Q

How many stable oxidation states do lanthanoids have ?

A

Only 1.

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2
Q

Why is the chemistry of actinkids complicated ?

A
  1. Wide range of oxidation states.
  2. Radioactivity
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3
Q

The most stable O.S of lanthanoids are

A

+ 3

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4
Q

Electronic configuration of lanthanoids

A

6s² 4f ( 1 - 14)

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5
Q

Lanthanoid contraction causes

A

Radii of 3rd series to be similar to the 2nd series.

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6
Q

Which elements are termed as lanthanoids ?

A

14 elements in the 6th period
( Z = 58 - 71)

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7
Q

Standard electrode value for Ce⁴/Ce³ is

A

+ 1.74 V

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8
Q

Behaviour of Samarium (Sm) is similar to the element ?

A

Europium ( Eu)

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9
Q

Oxidation states that Samarium exhibits

A

+2 and +3

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10
Q

Terbium with + 4 O.S has properties

A
  1. Oxidant
  2. Half filled f orbital
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11
Q

Ytterbium (Yb) with +2 O.S properties.

A
  1. f¹⁴ configuration
  2. Reductant
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12
Q

How is Eu ² ion formed ?

A
  1. Losing two s- electrons
  2. f ⁷ configuration
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13
Q

Property of Europium in +2 oxidation state.

A

Strong reducing agent.

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14
Q

Which elements can exhibit +4 oxidation states only in oxides MO²

A
  1. Praseodymium(Pr)
  2. Neodymium ( Nd)
  3. Terbium (Tb)
  4. Dysprosium (Dy)
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15
Q

Hardness of lanthanoid series

A

Hardness increases with atomic number.

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16
Q

Which element in the lanthanoid series is steel hard ?

A

Samarium.

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17
Q

lanthanoid elements on exposure to air .

A

Tarnish rapidly.

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18
Q

Physical property lanthanoids

A

1.Silvery white
2. soft metals.
3. Metallic structure
4. Good conductors

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19
Q

Range of melting points of lanthanoid elements .

A

1.1000 to 1200 K
2. Samarium - 1623 K

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20
Q

What affects the colours of the lanthanoid ions ?

A

Presence of f electrons

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21
Q

Whoch of the lanthanoid ions do not show any colour ?

A

1.Lanthanum - La³
2.Lutetium - Lu ³

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22
Q

Why are the absorption bands narrow in the lanthanoid series ?

A

Excitation within f levels.

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23
Q

Magnetic properties of lanthanoid ions.

A

All lanthanoid ions are paramagnetic.
Except f⁰ and f¹⁴

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24
Q

Which lanthanoid ions are NOT paramagnetic?

A
  1. f⁰ - La³ and Ce⁴
  2. f¹⁴ - Yb² and Lu³
25
Q

Ionisation entalpies of lanthanoids

A

A) I.E.1. 600 kJ /mol
B) I.E.2. 1200 kJ /mol

26
Q

Reactive behaviour of lanthanoid series is similar to the element ?

A

initially- calcium
Further - aluminium

27
Q

Properties of hydroxides of lanthanoids.

A
  1. M(OH)³
  2. Definite Compounds
  3. Basic in nature (like group 2 oxides)
28
Q

The best single use of lanthanoids

A

Production of alloy steels for plates and pipes.

29
Q

Well known alloy of lanthanoid

A

Mishmetall- 95% Ln and 5% iron

30
Q

Mishmetall is used in ?

A

Mg based alloys to produce bullets, shell and lighter flint.

31
Q

Mixed Oxides of lanthanoids are used for

A

Catalysts in petroleum cracking

32
Q

Individual oxides of lanthanoids are used as

A

Phosphors in television screens and flourescing surfaces.

33
Q

Ln with halogens form

A

LnX³

34
Q

Ln when heated with Sulphur gives

A

Ln² S³

35
Q

When Ln burns in O²

A

Ln ²O³

36
Q

Cerium (Ce) in +4 oxidation state is a

A

Strong oxidant.

37
Q

As ionic radius decreases from Praseodymium (Pr) to Lutetium (Lu) ?

A

Basicity decreases as well.

38
Q

Whoch elements have almost the same radii due to lanthanoid contraction ?

A

Zirconium (Zr) and Hafnium (Hf)

39
Q

Reason of lanthanoid contraction is

A

Negligible screening effect of f orbitals.

40
Q

Why do actinoids have more more number of oxidation states

A

Less energy difference between 5f and 6d orbitals than than between 4f and 5d.
Hence , 5f , 6d and 7s levels have comparable energies.

41
Q

General oxidation state of actinoids.

A

+3

42
Q

Which elements shows only +4 O.S in actinoids ?

A

Thorium (Th)

43
Q

Which elements of actinoids exhibit +7 oxidation state?

A

Neptunium (Np)
Plutonium (Pu)

44
Q

Which ions of actinoids tend to hydrolyse?

A

+3 and +4 ions

45
Q

Which elements of actinoids exhibit only +3 oxidation state?

A

Ac, Cf - Lr.

Actinium, Californium to lawrencium

46
Q

The actinoid contraction is caused by

A

Poor shielding of 5f electrons

47
Q

Half life of lawrencium (Lr)

A

3 minutes

48
Q

Ionisation enthalpies of actinoids series

A

Not accurately known but lower than that of lanthanoids.

49
Q

Which compound from transition metals is manufactured for the pigment industry ?

A

TiO

50
Q

Transition elements that the Battery industry requires

A

MnO² compound
Zinc, Nickel / Cadmium

51
Q

Elements of which group are termed as coinage metals .?

A

Group 11

52
Q

The silver UK coins are alloys of

A

Copper (Cu) and Nickel (Ni)

53
Q

The compound V²O⁵ is used for

A

Catalyst for oxidation of SO² in manufacture of sulphuric acid

54
Q

Zeigler catalyst is made of and used for

A

Made of TiCl⁴ and Al( CH³) ³
Used for manufacture of polyethylene ( polythene)

55
Q

Nickel catalysts are used for

A

Hydrogenation of fats

56
Q

What is the Wacker process

A

Oxidation of ethyne to ethanal, catalysed by PdCl²

57
Q

The photographer industries rely on light sensitive properties of

A

AgBr - Silver bromide.

58
Q

What catalyst is used for the Haber process

A

Iron catalyst

59
Q

What helps in polymerisation of alkyne?

A

Nickel complexes.

Chemistry (3 decks)

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