The Transition Elements and the Last Electron
Chapter:-8 The d-and f-Block Elements
POINTS TO BE REMEMBERED: ---
The elements of periodic table belonging to group 3 to 12 are known as d-Block elements.
The general electronic configuration of these elements is (n -1)d1-10 ns 1-2
d- Block elements are collectively known as Transition Elements because properties of these elements vary in between s-Block and p-Block elements.
A transition element should have partially filled (n-1) d orbital.
Group 12 elements i.e. Zn, Cd, Hg have completely filled (n-1) d-orbital in atomic & ionic state & thus these elements are considered as Typical Transition Elements.
All these elements are metals. They are less electropositive than s-block elements & more electropositive than p-block elements.
The atomic radii decreases from group 3 to 6 (i.e. Sc to Cr) because of increase in effective nuclear charge gradually.
The atomic radii of group 7,8 9 &10 elements (i.e. Fe,Co,Ni) is almost same because pairing of electrons take place in (n-1)d orbital causing repulsion i.e. shielding of (n-1)d orbital.
Group 11 &12 elements i.e. Cu & Zn have bigger size due to strong shielding of completely filled (n-1)d orbital.
The transition elements show variable oxidation state due to small energy difference between (n-1)d &ns orbital as a result both (n-1)d &ns electrons take part in bond formation.
The highest oxidation state of an element is equal to number of unpaired electrons present in (n-1)d &ns orbital.
Transition elements have high enthalpy of atomization/ sublimation Because of large number of unpaired electrons in their atoms, they have stronger interatomic interaction and hence strong metallic bonding is present between atoms.
Most of transition elements are paramagnetic due to presence of unpaired electrons in (n-1) d orbital.
Most of transition elements are used as catalyst. It is due to (i) partially filled (n-1) d orbital (ii) Variable oxidation state
POINTS TO BE REMEMBERED: ---
The elements of periodic table belonging to group 3 to 12 are known as d-Block elements.
The general electronic configuration of these elements is (n -1)d1-10 ns 1-2
d- Block elements are collectively known as Transition Elements because properties of these elements vary in between s-Block and p-Block elements.
A transition element should have partially filled (n-1) d orbital.
Group 12 elements i.e. Zn, Cd, Hg have completely filled (n-1) d-orbital in atomic & ionic state & thus these elements are considered as Typical Transition Elements.
All these elements are metals. They are less electropositive than s-block elements & more electropositive than p-block elements.
The atomic radii decreases from group 3 to 6 (i.e. Sc to Cr) because of increase in effective nuclear charge gradually.
The atomic radii of group 7,8 9 &10 elements (i.e. Fe,Co,Ni) is almost same because pairing of electrons take place in (n-1)d orbital causing repulsion i.e. shielding of (n-1)d orbital.
Group 11 &12 elements i.e. Cu & Zn have bigger size due to strong shielding of completely filled (n-1)d orbital.
The transition elements show variable oxidation state due to small energy difference between (n-1)d &ns orbital as a result both (n-1)d &ns electrons take part in bond formation.
The highest oxidation state of an element is equal to number of unpaired electrons present in (n-1)d &ns orbital.
Transition elements have high enthalpy of atomization/ sublimation Because of large number of unpaired electrons in their atoms, they have stronger interatomic interaction and hence strong metallic bonding is present between atoms.
Most of transition elements are paramagnetic due to presence of unpaired electrons in (n-1) d orbital.
Most of transition elements are used as catalyst. It is due to (i) partially filled (n-1) d orbital (ii) Variable oxidation state