# AP Inter 2nd Year Chemistry Notes Chapter 7 d and f Block Elements & Coordination Compounds

Students can go through AP Inter 2nd Year Chemistry Notes 7th Lesson d and f Block Elements & Coordination Compounds will help students in revising the entire concepts quickly.

## AP Inter 2nd Year Chemistry Notes 7th Lesson d and f Block Elements & Coordination Compounds

→ Transition elements are the elements which contains partially filled d-subshells in their ionic state (or) in their elementary state.
Eg : Mn, Co, Ag etc.

→ General electronic configuration of transition elements is (n – 1)d1-10 ns1-2.

→ Due to the presence of partially filled d-orbitals transition elements exhibit characteristic properties such as variable oxidation states, colour property, magnetic property, complex tendency etc.

→ Transition elements exhibits more than one oxidation state.
Reason:

• The energy difference between (n – 1) d subshell and ns subshell is very low. So both of these subshells compelete to lose the electrons.
• Zn+2 electronic configuration is [Ar] 4s03d10. It has no unpaired electrons. So it is diamagnetic.
• Mn+2 electronic configuration is [Ar] 4s03d5. It has five unpaired electrons so it is paramagnetic.

→ Complex compounds: Transition metal atoms or ions form a large number of compounds in which anions or neutral groups are bound to metal atom or ion through co-ordinate covalent bonds. Such compounds are called co-ordination compounds (or) complex compounds.
Eg. : [Fe(CN)6]4-, [Co(NH3)6]3+.

→ Alloy: An intimate mixture having physical properties similar to that of the metal formed by a metal with other metals or metalloids or sometimes a non metal is called as an alloy.
Eg.: Invar – 64% Fe, 35% Ni, Mn 8cc in traces
Nichrome – 60% Ni, 25% Fe, 15% Cr.

→ The slow decrease of atomic and ionic radii in lanthanides with increase in atomic number is called lanthanide contraction.

→ Mischmetall is an alloy which consists of a lanthanoid metal (~ 95%) and iron (~ 5%) and traces of S, C, Ca and Al.
It is used in Mg- based alloy to produce bullets, shell and lighter flint.

→ The spatial arrangement of the ligands which are directly bonded to the central atom or ions defines the geometry about the central atom is called co-ordination polyhedron
Eg.: Octahedral, tetrahedral etc.

→ Ligand : A co-ordinating entity which is bound to the central atom by donating electron pairs is called a ligand.
Eg. : Cl, NH3, CN etc.

→ The ligands which can form two co-ordinate covalent bonds through two donar atoms are called bidentate ligands. These bidentate ligands are also called chelate ligands.
Eg. : C2O4-2, CO3-2 etc.

→ A unidentate ligand containing two possible donor atoms can co-ordinate through either of donor atoms. Such ligands are called ambidentate ligands.
Eg : $$\mathrm{NO}_2^{-}$$

→ Homoleptic complexes : These are the complexes in which a metal is bound by only are kind of ligands.
Eg.: [CO(NH3)6]3+

→ Heteroleptic complexes : These are the complexes in which a metal is bound by more than one kind of ligends.
Eg.: [Co(NH3)4Cl2]+.