Explain Why Questions in Transition Elements - Inorganic chemistry questions and answers (Part 1)
Inorganic chemistry questions and answersTransition Elements
Explain
why?
1.
Copper has irregular electronic
configuration or Copper contains only one electron in s-orbital.
Answer:
Because
copper has the electronic configuration [Ar] 3d10 4s1
because this gives it more stability since d orbital is completely filled.
29Cu [Ar] 3d10 4s1
2.
Chromium has irregular electronic
configuration or Chromium contains only one electron in s-orbital.
Answer:
Chromium
it has the electronic configuration [Ar] 3d5 4s1 because
this is gives it more stability since d orbital is half filled.
24Cr [Ar] 3d5 4s1
3.
The greater ability of transition
elements to form complexes.
Answer:
The
transition elements can form complexes because they act as Lewis acid (i.e.
accept lone pairs of electrons) because they form small, highly charged ions,
and have incomplete d-orbital in which they can accept electrons.
4.
The transition elements form colored
complexes (or compounds).
Answer:
-
The colors of transition elements compounds are due
to:
a.
Electronic transitions of d-electrons within the d
sub-shell. These are known as d→d transitions, and d0 and d10
metal ions do not show these transitions.
b.
Electronic transitions from the metal ion to the
ligand (M→L transitions) or ligand to the metal ion (L→M transitions), which
are known as charge-transfer transitions, and these can occur for d0
to d10 metal ions.
c.
The intra ligand transitions: The ligands themselves
may be colored, and this color may contribute to the color of the complex.
-
Also, color may arise from the acid radical or due to
defects in crystal structure
5. CuSO4 is blue:
Answer:
Cu oxidation state in CuSO4 is +2 and its configuration [Ar] 3d9 4s0 So, d-d electronic transition can occur, and the compound appears blue (the complementary color to the color it absorbs).
6. ZnSO4 is colorless:
Answer:
Zn oxidation state in ZnSO4 is +2 and its configuration [Ar] 3d10 4s0 So, NO d-d electronic transition can occur, and the compound appears colorless.
7. TiO2 is colorless:
Answer:
Ti oxidation state in TiO2 is +4 and its configuration [Ar] 3d0 4s0 So, no d-d electronic transition can occur, and the compound appear colorless.
8. KMnO4 is violet:
Answer:
Mn in KMnO4 is +7 and its configuration [Ar] 3d0 4s0 and therefore the violet color is due to the charge transfer transition i.e. the transition of electrons from the ligand into the empty orbitals of Mn.
9.
Cu2+
compounds are colored while Cu+ compounds are colorless.
Answer:
Because Cu+ configuration is [Ar] 3d10 4s0 so, it cannot undergo d-d transitions so its compounds are colorless but Cu2+ configuration is [Ar] 3d9 4s0 so, it can undergo d-d transitions, so its compounds are colored.
10.The covalent
radii of elements decrease from left to right across a row.
Answer:
Because on passing from
left to right extra positive charges increased in the nucleus and extra
electrons are added in the d orbital but the d-orbitals shield the nucleus
charge incompletely (d-electrons shield less than p-electrons and p less than
s-electrons) so, the nuclear charge attracts the outer electrons more and the
size decrease.
11.The second
and third row elements have similar properties, or It is difficult to separate
the second-row element from the third-row elements
Answer:
Because the normal
increase in size on descending the group from the second row to the third row
almost exactly cancelled by the decrease in size caused by filling 14 electrons
in 4f level (this called lanthanide contraction) so the second row and third
row elements have similar properties
12.The high
densities of transition elements.
Answer:
Because they have small
volumes.
13.The high
melting and boiling points of transition elements.
Answer:
Due to the small size and
the increase of the number of unpaired electrons, so they have strong metallic
bond and therefore have high melting and boiling points.
14.
Mercury is liquid metal.
Answer:
This is due to the very high ionization energy
making it difficult for electrons to participate in metallic bonding.
15.Transition
elements are less reactive than s-block elements.
Answer:
Due to:
1.
Smaller size
2.
High sublimation energy
3.
High ionization energy
4.
high melting point
16.Transition
elements are less electropositive than s-block elements
Answer:
Because they are smaller than s-block
elements and therefore have higher ionization energies, so they are less
reactive
17.Transition
elements show catalytic properties or transition elements used as
catalysts.
Answer:
Because they have variable oxidation
states and may form unstable intermediates or in other cases the transition
element provides suitable reaction surface therefore decrease the activation
energy of a reaction.
18.Transition
elements form compounds of indefinite structure.
Answer:
This phenomenon is called
nonstoichiometry and appears in transition elements due to their variable
oxidation states and defects in solid structure
19. The (+III)
oxidation state of group IIIB is colorless and diamagnetic.
Answer:
Because in this oxidation
state the group IIIB elements contain d0 and so the ions and their
compounds are colorless and diamagnetic.
20.The covalent
and ionic radii of elements increase regularly on descending in group IIIB.
Answer:
This because the
lanthanides contraction does not appear in group IIIB but it is presents
starting from group IVB.
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