F Block Flashcards
How many stable oxidation states do lanthanoids have ?
Only 1.
Why is the chemistry of actinkids complicated ?
- Wide range of oxidation states.
- Radioactivity
The most stable O.S of lanthanoids are
+ 3
Electronic configuration of lanthanoids
6s² 4f ( 1 - 14)
Lanthanoid contraction causes
Radii of 3rd series to be similar to the 2nd series.
Which elements are termed as lanthanoids ?
14 elements in the 6th period
( Z = 58 - 71)
Standard electrode value for Ce⁴/Ce³ is
+ 1.74 V
Behaviour of Samarium (Sm) is similar to the element ?
Europium ( Eu)
Oxidation states that Samarium exhibits
+2 and +3
Terbium with + 4 O.S has properties
- Oxidant
- Half filled f orbital
Ytterbium (Yb) with +2 O.S properties.
- f¹⁴ configuration
- Reductant
How is Eu ² ion formed ?
- Losing two s- electrons
- f ⁷ configuration
Property of Europium in +2 oxidation state.
Strong reducing agent.
Which elements can exhibit +4 oxidation states only in oxides MO²
- Praseodymium(Pr)
- Neodymium ( Nd)
- Terbium (Tb)
- Dysprosium (Dy)
Hardness of lanthanoid series
Hardness increases with atomic number.
Which element in the lanthanoid series is steel hard ?
Samarium.
lanthanoid elements on exposure to air .
Tarnish rapidly.
Physical property lanthanoids
1.Silvery white
2. soft metals.
3. Metallic structure
4. Good conductors
Range of melting points of lanthanoid elements .
1.1000 to 1200 K
2. Samarium - 1623 K
What affects the colours of the lanthanoid ions ?
Presence of f electrons
Whoch of the lanthanoid ions do not show any colour ?
1.Lanthanum - La³
2.Lutetium - Lu ³
Why are the absorption bands narrow in the lanthanoid series ?
Excitation within f levels.
Magnetic properties of lanthanoid ions.
All lanthanoid ions are paramagnetic.
Except f⁰ and f¹⁴
Which lanthanoid ions are NOT paramagnetic?
- f⁰ - La³ and Ce⁴
- f¹⁴ - Yb² and Lu³
Ionisation entalpies of lanthanoids
A) I.E.1. 600 kJ /mol
B) I.E.2. 1200 kJ /mol
Reactive behaviour of lanthanoid series is similar to the element ?
initially- calcium
Further - aluminium
Properties of hydroxides of lanthanoids.
- M(OH)³
- Definite Compounds
- Basic in nature (like group 2 oxides)
The best single use of lanthanoids
Production of alloy steels for plates and pipes.
Well known alloy of lanthanoid
Mishmetall- 95% Ln and 5% iron
Mishmetall is used in ?
Mg based alloys to produce bullets, shell and lighter flint.
Mixed Oxides of lanthanoids are used for
Catalysts in petroleum cracking
Individual oxides of lanthanoids are used as
Phosphors in television screens and flourescing surfaces.
Ln with halogens form
LnX³
Ln when heated with Sulphur gives
Ln² S³
When Ln burns in O²
Ln ²O³
Cerium (Ce) in +4 oxidation state is a
Strong oxidant.
As ionic radius decreases from Praseodymium (Pr) to Lutetium (Lu) ?
Basicity decreases as well.
Whoch elements have almost the same radii due to lanthanoid contraction ?
Zirconium (Zr) and Hafnium (Hf)
Reason of lanthanoid contraction is
Negligible screening effect of f orbitals.
Why do actinoids have more more number of oxidation states
Less energy difference between 5f and 6d orbitals than than between 4f and 5d.
Hence , 5f , 6d and 7s levels have comparable energies.
General oxidation state of actinoids.
+3
Which elements shows only +4 O.S in actinoids ?
Thorium (Th)
Which elements of actinoids exhibit +7 oxidation state?
Neptunium (Np)
Plutonium (Pu)
Which ions of actinoids tend to hydrolyse?
+3 and +4 ions
Which elements of actinoids exhibit only +3 oxidation state?
Ac, Cf - Lr.
Actinium, Californium to lawrencium
The actinoid contraction is caused by
Poor shielding of 5f electrons
Half life of lawrencium (Lr)
3 minutes
Ionisation enthalpies of actinoids series
Not accurately known but lower than that of lanthanoids.
Which compound from transition metals is manufactured for the pigment industry ?
TiO
Transition elements that the Battery industry requires
MnO² compound
Zinc, Nickel / Cadmium
Elements of which group are termed as coinage metals .?
Group 11
The silver UK coins are alloys of
Copper (Cu) and Nickel (Ni)
The compound V²O⁵ is used for
Catalyst for oxidation of SO² in manufacture of sulphuric acid
Zeigler catalyst is made of and used for
Made of TiCl⁴ and Al( CH³) ³
Used for manufacture of polyethylene ( polythene)
Nickel catalysts are used for
Hydrogenation of fats
What is the Wacker process
Oxidation of ethyne to ethanal, catalysed by PdCl²
The photographer industries rely on light sensitive properties of
AgBr - Silver bromide.
What catalyst is used for the Haber process
Iron catalyst
What helps in polymerisation of alkyne?
Nickel complexes.
