Chapter 22, Problem 22.56P

Interpretation Introduction

(a)

Interpretation:

To explain why the given Lewis structure of CO is not acceptable.

Concept introduction:

Lewis structure is written by distributing the total valence electrons of each atoms involved in bonding, around each atom such that octet of each atom gets completed. Each electron is shown by a dot. If a positive charge is present on the ion then electrons equal to the charge on the ion must be subtracted from the total valence electrons and if a negative charge is present then that much electrons must be added to the total valence electrons.

Answer to Problem 22.56P

The given Lewis structure for $\text{CO}$ molecule is not acceptable because the octet of carbon atom is not completed.

Explanation of Solution

In the given Lewis structure of CO the octet of O atom is complete but the octet of carbon atom is incomplete as shown below:

In the above structure around the oxygen atom there are eight electrons but around the carbon atom there are only six electrons that is the given structure does not follow the octet rule hence the given Lewis structure is not acceptable.

Interpretation Introduction

(b)

Interpretation:

The Lewis structure for the $\text{CO}$ must be drawn.

Concept introduction:

Lewis structure is written by distributing the total valence electrons of each atoms involved in bonding, around each atom such that octet of each atom gets completed. Each electron is shown by a dot. If a positive charge is present on the ion, then electrons equal to the charge on the ion must be subtracted from the total valence electrons and if a negative charge is present then that much electrons must be added to the total valence electrons.

Answer to Problem 22.56P

The Lewis structure for $\text{CO}$ is.

Explanation of Solution

The atomic number of C and CO is 6 and 8 and their electronic configurations are ${\text{1s}}^2{\text{2s}}^2{\text{2p}}^2$, and ${\text{1s}}^2{\text{2s}}^2{\text{3p}}^4$ the valence electrons of C are 4 and of O is 6. The skeleton of the $\text{CO}$ molecule is drawn.

In $\text{CO}$ there are one C and one O atom therefore total valence electrons are equal $4+6=10$. Now these valence electrons are distributed around the C and one O atom such that octet of each atom gets completed.

The Lewis structure for $\text{CO}$ is.

Interpretation Introduction

(c)

Interpretation:

To identify which electron pair is donated by the CO to the Fe metal for the formation of a coordinate covalent bond.

Concept introduction:

Lewis structure is written by distributing the total valence electrons of each atoms involved in bonding, around each atom such that octet of each atom gets completed. Each electron is shown by a dot. If a positive charge is present on the ion, then electrons equal to the charge on the ion must be subtracted from the total valence electrons and if a negative charge is present then that much electrons must be added to the total valence electrons.

Answer to Problem 22.56P

The lone pair of electron present on the C-atom donated to the Fe metal to form the coordinate covalent bond in $\text{Fe}{\left(\text{CO}\right)}_5$.

Explanation of Solution

In $\text{Fe}{\left(\text{CO}\right)}_5$ complex the Fe is the central metal ion and the CO is a ligand. Five molecules of CO coordinates with the Fe metal atom by donation of a pair of electrons by each CO ligand to the Fe metal. And since the bond is formed between the carbon atom of CO and the Fe metal ion therefore, the electron pair present on the carbon atom is involved in the formation of a coordinate covalent bond in $\text{Fe}{\left(\text{CO}\right)}_5$

Interpretation Introduction

(d)

Interpretation:

The Lewis structure for the ${\text{O}}_2$ has to be drawn and it has to be shown that how the ${\text{O}}_2$ forms a coordinate covalent bond with ${\text{Fe}}^{2+}$ ion.

Concept introduction:

Lewis structure is written by distributing the total valence electrons of each atoms involved in bonding, around each atom such that octet of each atom gets completed. Each electron is shown by a dot. If a positive charge is present on the ion, then electrons equal to the charge on the ion must be subtracted from the total valence electrons and if a negative charge is present then that much electrons must be added to the total valence electrons.

Answer to Problem 22.56P

The Lewis structure for ${\text{O}}_2$ is.

Explanation of Solution

The atomic number of O is 8 and its electronic configuration is ${\text{1s}}^2{\text{2s}}^2{\text{2p}}^4$ the valence electrons for O is 6. The skeleton of the ${\text{O}}_2$ molecule is drawn.

In ${\text{O}}_2$ there are two O atoms therefore, the total valence electrons will be equal to $2\times 6=12$. Now these valence electrons are distributed around the two O atoms such that octet of each atom gets completed.

A coordinate covalent bond is formed when a donor molecule called as ligand donates a pair of electrons to the central metal atom. In case of ${\text{Fe}}^{2+}$ ion the atomic number of Fe is 26, its outermost electronic configurations is $\left[\text{Ar}\right]3{\text{d}}^6{\text{4s}}^2$ since a charge of +2 is present on ${\text{Fe}}^{2+}$ ion therefore, two electrons must be subtracted from the outermost electrons of the Fe atom now the electronic configuration of ${\text{Fe}}^{2+}$ ion will become $\left[\text{Ar}\right]3{\text{d}}^6{\text{4s}}^0$. In the haemoglobin and myoglobin the central ${\text{Fe}}^{2+}$ ion has six coordination sites among which four coordination sites are occupied by N-atoms of the porphyrin ring, the fifth site is coordinated with the N-atom of histidine side chain and the sixth site is coordinated with the ${\text{O}}_2$ molecule. Each donor atom donates an electron pair to the ${\text{Fe}}^{2+}$ ion.