Explain
giving reasons:
(i)
Transition metals and many of their compounds show paramagnetic
behaviour.
(ii)
The enthalpies of atomisation of the
transition metals are high.
(iii)
The transition metals generally form
coloured compounds.
(iv)
Transition metals and their many
compounds act as good catalyst.
Explain giving reasons:
(i) Transition metals and many of their compounds show paramagnetic
behaviour.
(ii) The enthalpies of atomisation of the transition metals are high.
(iii) The transition metals generally form coloured compounds.
(iv) Transition metals and their many compounds act as good catalyst.
(i) Transition
metals show paramagnetic behaviour. Paramagnetism arises due to the
presence of unpaired electrons with each electron having a magnetic
moment associated with its spin angular momentum and orbital angular
momentum. However, in the first transition series, the orbital
angular momentum is quenched. Therefore, the resulting paramagnetism
is only because of the unpaired electron.
(ii) Transition
elements have high effective nuclear charge and a large number of
valence electrons. Therefore, they form very strong metallic bonds.
As a result, the enthalpy of atomization of transition metals is
high.
(iii) Most of the
complexes of transition metals are coloured. This is because of the
absorption of radiation from visible light region to promote an
electron from one of the d−orbitals
to another. In the presence of ligands, the d-orbitals
split up into two sets of orbitals having different energies.
Therefore, the transition of electrons can take place from one set toanother. The energy required for these
transitions is quite small and falls in the visible region of
radiation. The ions of transition metals absorb the radiation of a
particular wavelength and the rest is reflected, imparting colour to
the solution.
(iv) The
catalytic activity of the transition elements can be explained by two
basic facts.
(a) Owing to
their ability to show variable oxidation states and form complexes,
transition metals form unstable intermediate compounds. Thus, they
provide a new path with lower activation energy, Ea,
for the reaction.
(b) Transition
metals also provide a suitable surface for the reactions to occur.
(i) Transition metals show paramagnetic behaviour. Paramagnetism arises due to the presence of unpaired electrons with each electron having a magnetic moment associated with its spin angular momentum and orbital angular momentum. However, in the first transition series, the orbital angular momentum is quenched. Therefore, the resulting paramagnetism is only because of the unpaired electron.
(ii) Transition elements have high effective nuclear charge and a large number of valence electrons. Therefore, they form very strong metallic bonds. As a result, the enthalpy of atomization of transition metals is high.
(iii) Most of the complexes of transition metals are coloured. This is because of the absorption of radiation from visible light region to promote an electron from one of the d−orbitals to another. In the presence of ligands, the d-orbitals split up into two sets of orbitals having different energies. Therefore, the transition of electrons can take place from one set toanother. The energy required for these transitions is quite small and falls in the visible region of radiation. The ions of transition metals absorb the radiation of a particular wavelength and the rest is reflected, imparting colour to the solution.
(iv) The catalytic activity of the transition elements can be explained by two basic facts.
(a) Owing to their ability to show variable oxidation states and form complexes, transition metals form unstable intermediate compounds. Thus, they provide a new path with lower activation energy, Ea, for the reaction.
(b) Transition metals also provide a suitable surface for the reactions to occur.
