For the central metal atom in a complex, coordination number isa)The number of ligands bonded by pi-bonds that surround a metal ion.b)The number of ligands bonded by sigma-bonds that surround a metal ion.c)The number of ligands bonded by pi-bonds and sigma bonds that surround a metal ion.d)The number of only neutral ligands bonded to the metal ionCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

The coordination number of a central metal atom in a complex refers to the number of ligands bonded by sigma-bonds that surround the metal ion.

Explanation:
A coordination complex consists of a central metal atom or ion bonded to one or more ligands. The coordination number of the central metal atom determines the number of ligands that are directly bonded to it. The coordination number is an important factor in determining the geometry and properties of the complex.

Definition of coordination number:
The coordination number is defined as the number of sigma-bonds formed between the central metal atom and the ligands. A sigma-bond is a type of covalent bond formed by the overlap of orbitals.

Key points:
Here are some key points to understand why the correct answer is option 'B':

1. Sigma-bonds: In a coordination complex, the ligands are bonded to the central metal atom through sigma-bonds. A sigma-bond is formed by the direct overlap of orbitals between the metal atom and the ligand.

2. Pi-bonds: Pi-bonds are formed by the sideways overlap of p-orbitals. Pi-bonds are not considered when determining the coordination number because they do not directly involve the metal-ligand bonding.

3. Neutral ligands: The coordination number only considers the number of ligands bonded to the metal atom, regardless of their charge. Neutral ligands and charged ligands can form sigma-bonds with the metal atom.

4. Counting ligands: To determine the coordination number, count the number of sigma-bonds formed between the metal atom and the ligands. Each sigma-bond contributes one to the coordination number.

5. Examples: For example, in a complex where a metal atom is bonded to four ligands through sigma-bonds, the coordination number is 4. Similarly, if a metal atom is bonded to six ligands through sigma-bonds, the coordination number is 6.

Therefore, the coordination number of a central metal atom in a complex is the number of ligands bonded by sigma-bonds that surround the metal ion. This is why the correct answer is option 'B'.

Answer

Coordination number is the number of ligands that surround the metal ion and are linked to it through sigma bonds.

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