Explain with two examples each of the following: coordination entity,ligand,coordination number,coordination polyhedron,homoleptic and heteroleptic.

(N/A) $(i)$ Coordination entity:
$A$ coordination entity is an electrically charged radical or species. In a coordination entity,the central atom or ion is surrounded by a suitable number of neutral molecules or negative ions (called ligands). For example:
Cationic complex: $[Ni(NH_3)_6]^{2+}, [Fe(H_2O)_6]^{3+}$
Anionic complex: $[PtCl_4]^{2-}, [Ag(CN)_2]^{-}$
$(ii)$ Ligands:
The neutral molecules or negatively charged ions that surround the metal atom in a coordination entity are known as ligands. For example,$NH_3$ and $Cl^-$.
$(iii)$ Coordination number:
The total number of ligand donor atoms to which the central metal atom is directly bonded is called the coordination number. For example:
$(a)$ In $[PtCl_6]^{2-}$,the coordination number of $Pt$ is $6$.
$(b)$ In $[Ni(NH_3)_4]^{2+}$,the coordination number of $Ni$ is $4$.
$(iv)$ Coordination polyhedron:
It is the spatial arrangement of the ligand atoms which are directly attached to the central atom/ion. Examples include square planar and tetrahedral geometries.
$(v)$ Homoleptic complexes:
These are complexes in which the metal ion is bound to only one kind of donor group. For example: $[Co(NH_3)_6]^{3+}, [Ni(CO)_4]$.
$(vi)$ Heteroleptic complexes:
These are complexes where the central metal ion is bound to more than one type of donor group. For example: $[Co(NH_3)_4Cl_2]^{+}, [Co(NH_3)_5Cl]^{2+}$