Question

In the complex ion \[{\left[ {{\text{Fe}}\left( {{\text{EDTA}}} \right)} \right]^{\text{ - }}}\] the coordination number and oxidation state of central metal ion is:
A) CN = \[6\] ON = \[ + 3\]
B) CN = \[1\] ON = \[ - 1\]
C) CN = \[4\] ON = \[ + 2\]
D) CN = \[3\] ON = \[ + 3\]

Answer 1

Hint: We need to know that in chemistry three types of chemical bond. There are ionic bonds, covalent bonds and coordinate bonds. The coordination chemistry in one of the major topics in chemistry. The coordination bond plays an important role in coordination chemistry. The complex is formed in nature, basic coordination chemistry. The full form of \[{\text{EDTA}}\] is EthyleneDiamineTetraAceticacid.

Complete answer:
We also remember that the metal atom present in the complex is called a central metal atom. The atom which donates a lone pair of electrons to the central atom or the coordinate bond with the central atom is known as ligand.
As we know that the oxidation state of the central metal atom is equal to the number of primary valencies. The coordination number of the central metal atom is equal to the secondary valency.
In \[{\left[ {{\text{Fe}}\left( {{\text{EDTA}}} \right)} \right]^{\text{ - }}}\]
The central atom is \[{\text{Fe}}\] and the ligand is \[{\text{EDTA}}\].
The number of lone pairs donating atoms in \[{\text{EDTA}}\] is \[6\].
The oxidation state of\[{\left[ {{\text{Fe}}\left( {{\text{EDTA}}} \right)} \right]^{\text{ - }}}\] is \[ + 3\].
The coordination number and oxidation number of \[{\left[ {{\text{Fe}}\left( {{\text{EDTA}}} \right)} \right]^{\text{ - }}}\] is \[6\]and \[ + 3\].

Hence, option A is correct because CN = \[6\] ON = \[ + 3\]

Note:
We also remember that in chemistry, substances are majorly divided into two types. This classification is dependent on the stability of the substance. Compound and complex are the classification of the substance in the chemistry. In coordination chemistry, primary and secondary valency in the complex. The primary valencies are ionic bonds. The primary valencies are non-directional. The secondary valencies are coordinate bonds. The secondary valence is directional. The structure of the complex is dependent on the secondary valence.