D block elements
Physical Properties of D block elements
1. The d-block elements are also called as Transition elements. And the f-block elements are called as the inner-transition elements.
2. The d-block elements are found in the groups 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 of the periodic table. There is a special name given to the period 6 and 7 called as Lanthanide and Actinide series
3. These are called d-block elements, because there last electron enters the d-shell. The number of valence electrons is a d-sub shell are 10.
4. There are mainly four series namely
:3d series (Ist series) - From Sc to Zn
: 4d series (IInd series) - From Y to Cd
: 5d series (IIIrd series) - From La to Hg (excluding Ce to Lu)
: 6d series (IVth series) - Starting from Ac
5. The electronic configuration of d-block elements is (n-1)d ns . The (n–1) stands for the inner d orbitals which may have one to ten electrons and the outermost ns orbital may have one or two electrons.
6. But Zn, Hg, Cd and the end members of the first three series have the general configuration
i.e. (n-1)d n
7. Physical Properties:
1) Atomic Radii The nuclear radii of the d-block elements inside a given series decrease with increment in the nuclear number. This is because of the expansion in the atomic charge that attracts the electron cloud inwards bringing about a decrease in size.
2) Ionic Radii The pattern of ionic radius is similar to the atomic radii pattern. Hence, for ions of a given charge the radius decreases gradually with an increment in atomic number.
3)Ionization Enthalpies Transition elements have high ionization energy because of their small size. Their ionization potentials lie between those of S and P block elements.
4) Melting and boiling points They show very high melting and boiling points. This can be attributed to the presence of strong metallic bonding due to the overlapping of (n-1) d orbitals and covalent bonding of the unpaired d-orbital electrons
5)Atomic Volume and density The atomic volume of transition elements is much lower than those of S and P block elements. This is because of the filling of the (n-1)d orbitals that cause an increase in the nuclear charge and pulls the electrons inward. This results in decrease in atomic volume. With the decrease in the atomic volume, the atomic density of these elements increases.
6)Oxidation states All the transition elements, aside from the first and last individuals from the series, display various oxidation states. They indicate variable valency in their compounds.
7) Magnetic properties The magnetic properties of d-block Elements are dictated by the number of unpaired electrons in it. These are divided into two types: (a) Paramagnetic substances The paramagnetic character is due to presence of unpaired electrons. These are attracted by the magnetic field. (b) Diamagnetic Substances The diamagnetic character is due to the presence of paired electrons. These are repelled by the magnetic field.
8) Formation of Colored Ions The color in transition elements is due to the presence of unpaired electrons. Also, it is due to d-d transition in these elements, when invisible light is thrown on ion. In transition elements, the electrons can be advanced from one energy level to another energy level in a similar d-subshell. This indicates the colour formation.
Note:
Note: The atomic radii in the second and third series is same as we can also
see in the above figure.
This is due to lanthanide contraction which occurs
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| Periodic table |
1. The d-block elements are also called as Transition elements. And the f-block elements are called as the inner-transition elements.
2. The d-block elements are found in the groups 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 of the periodic table. There is a special name given to the period 6 and 7 called as Lanthanide and Actinide series
3. These are called d-block elements, because there last electron enters the d-shell. The number of valence electrons is a d-sub shell are 10.
4. There are mainly four series namely
:3d series (Ist series) - From Sc to Zn
: 4d series (IInd series) - From Y to Cd
: 5d series (IIIrd series) - From La to Hg (excluding Ce to Lu)
: 6d series (IVth series) - Starting from Ac
5. The electronic configuration of d-block elements is (n-1)d ns . The (n–1) stands for the inner d orbitals which may have one to ten electrons and the outermost ns orbital may have one or two electrons.
6. But Zn, Hg, Cd and the end members of the first three series have the general configuration
i.e. (n-1)d n
7. Physical Properties:
1) Atomic Radii The nuclear radii of the d-block elements inside a given series decrease with increment in the nuclear number. This is because of the expansion in the atomic charge that attracts the electron cloud inwards bringing about a decrease in size.
2) Ionic Radii The pattern of ionic radius is similar to the atomic radii pattern. Hence, for ions of a given charge the radius decreases gradually with an increment in atomic number.
3)Ionization Enthalpies Transition elements have high ionization energy because of their small size. Their ionization potentials lie between those of S and P block elements.
4) Melting and boiling points They show very high melting and boiling points. This can be attributed to the presence of strong metallic bonding due to the overlapping of (n-1) d orbitals and covalent bonding of the unpaired d-orbital electrons
5)Atomic Volume and density The atomic volume of transition elements is much lower than those of S and P block elements. This is because of the filling of the (n-1)d orbitals that cause an increase in the nuclear charge and pulls the electrons inward. This results in decrease in atomic volume. With the decrease in the atomic volume, the atomic density of these elements increases.
6)Oxidation states All the transition elements, aside from the first and last individuals from the series, display various oxidation states. They indicate variable valency in their compounds.
7) Magnetic properties The magnetic properties of d-block Elements are dictated by the number of unpaired electrons in it. These are divided into two types: (a) Paramagnetic substances The paramagnetic character is due to presence of unpaired electrons. These are attracted by the magnetic field. (b) Diamagnetic Substances The diamagnetic character is due to the presence of paired electrons. These are repelled by the magnetic field.
8) Formation of Colored Ions The color in transition elements is due to the presence of unpaired electrons. Also, it is due to d-d transition in these elements, when invisible light is thrown on ion. In transition elements, the electrons can be advanced from one energy level to another energy level in a similar d-subshell. This indicates the colour formation.
The figure below describes the trends in the atomic radii of the transition electron
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| Variation of atomic radii |
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