Manganese exhibit largest number of oxidation states, because it has highest number of unpaired electrons. here is the example.
The enthalpy of hydration of Cu+2 is enough negative which can easily compensate the second ionisation energy of copper. That is why Cu+2 ions are more stable in the aqueous solution.
The elements in which the last electron is filled in f-subshell are called inner transition metals. These are also known as f-block elements.
These are the elements in which the outermost electron is filled in 5f-subshell.
The elements from atomic number 89 (Actinium) to 103 Lawrencium, involving the filling of 5f-subshell.
In case of inner transition elements there are three incomplete orbitals. these are s, d , and f .
It the phenomenon in which the atomic radii of elements decrease from Lanthanum to Lutetium. Or more simply it is the decrease in atomic radii when we move from La to Lu .
This is because of the lanthanoid contraction as in case of 3rd transition series, the filling of f-subshell takes place. The screening effect of f-subshell is least . Due to this the effective nuclear charge experienced by 3rd transition series is quite high. The increase in size due to increase in shell numbers is overcame
It is due to the lanthanoid contraction.
In case of Zr and Hf the lanthanoid contraction takes place which accounts for the similar atomic size and because of similar size they are found together.
The atomic radii of both the elements is similar, due to which their physical properties also match. so these are very difficult to separate by physical methods.
The lanthenoids show the following configuration :- Ln – 4f 1-14 5 s2 5s6 6s2 And configuration of Calcium is :- Ca- [Ar] 4s2 In both of the cases there are 2 electrons in outer s-subshell. Thus ionisation enthalpies of lanthenoids are comparable to the Calcium.
Europium is the element that shows very low value of third ionisation enthalpy.
Mischmetal is an alloy having the following components:- Lanthenoids 95% Iron 5% Traces of Sulphur , Carbon , Calcium and Aluminium
The uses of mischmetal are :- To produce bullets Lighter flint Shells
Lanthanoid oxide is the compound used as phosphors in T.V. screen.
The mixed oxides of lanthanoids are used in the cracking of petrolium .
Protactinium (Pa) is the element that starts the filling of 5f subshell.
This is because of two reasons:-
It is the phenomenon of regular decrease in size as we move from Actinium to Lawrencium due the poor shielding effect of f- subshell.
The most common oxidation state shown by the actinoids is +3
Maximum or highest oxidation state of actinoids is +4.
Minimum oxidation state shown by the lanthenoids is +2 .