Question

Calculate the formal charges on the Oxygen atoms in the following molecules: HPO42-, CH3COO-, and CH3−CH(OH)−CH.

Answer 1

To calculate the formal charge on an atom in a molecule, we use the following formula:

Formal charge = valence electrons - lone pair electrons - 1/2(bonding electrons)

where valence electrons are the number of electrons an atom has in its outermost shell, lone pair electrons are the electrons that are not involved in bonding and are located on the atom, and bonding electrons are the electrons shared between two atoms in a bond.

Let's apply this formula to the Oxygen atoms in the given molecules:

1. HPO42-

The Lewis structure for HPO42- is:

H

|

O

/ \

O P

/ \

O O

2-

To calculate the formal charge on each Oxygen atom, we use the formula:

For O1: Formal charge = 6 valence electrons - 4 lone pair electrons - 1/2(6 bonding electrons) = 0

For O2: Formal charge = 6 valence electrons - 6 lone pair electrons - 1/2(4 bonding electrons) = -1

For O3: Formal charge = 6 valence electrons - 6 lone pair electrons - 1/2(4 bonding electrons) = -1

For O4: Formal charge = 6 valence electrons - 4 lone pair electrons - 1/2(6 bonding electrons) = 0

Therefore, the formal charges on the Oxygen atoms in HPO42- are: 0, -1, -1, and 0.

2. CH3COO-

The Lewis structure for CH3COO- is:

H H

| |

C C

//\\ / \

O C O O

|

1-

To calculate the formal charge on each Oxygen atom, we use the formula:

For O1: Formal charge = 6 valence electrons - 4 lone pair electrons - 1/2(4 bonding electrons) = -1

For O2: Formal charge = 6 valence electrons - 4 lone pair electrons - 1/2(2 bonding electrons) = -1

Therefore, the formal charges on the Oxygen atoms in CH3COO- are: -1 and -1.

3. CH3−CH(OH)−CH

The Lewis structure for CH3−CH(OH)−CH is:

H H

| |

C C

// //

H O

|

C

|

H

To calculate the formal charge on the Oxygen atom, we use the formula:

For O: Formal charge = 6 valence electrons - 2 lone pair electrons - 1/2(2 bonding electrons) = -1

Therefore, the formal charge on the Oxygen atom in CH3−CH(OH)−CH is -1.

Answer 2

Answer and Explanation:

To calculate the formal charges on oxygen atoms in molecules, we need to consider the valence electrons and the way they are shared in the molecule. Let's analyze the three given molecules:

1. HPO42-

- The molecule has four oxygen atoms. Each oxygen atom has six valence electrons.

- In the phosphate ion (PO42-), one oxygen atom forms a double bond with the phosphorus atom (P), and the other three oxygen atoms form single bonds.

- We assign two electrons to each bond and distribute the remaining valence electrons around each oxygen atom.

- The formal charge on each oxygen atom can be calculated using the formula: Formal charge = (Number of valence electrons) - (Number of lone pair electrons) - (Number of shared electrons / 2).

- Calculating the formal charges for each oxygen atom gives us:

- Oxygen 1: 6 - 6 - (6/2) = 0

- Oxygen 2: 6 - 6 - (6/2) = 0

- Oxygen 3: 6 - 6 - (6/2) = 0

- Oxygen 4: 6 - 6 - (6/2) = 0

- In this case, all the oxygen atoms in HPO42- have a formal charge of 0.

2. CH3COO-

- The molecule consists of two oxygen atoms. Each oxygen atom has six valence electrons.

- In the acetate ion (CH3COO-), one oxygen atom forms a double bond with the carbon atom (C), and the other oxygen atom forms a single bond.

- We assign two electrons to each bond and distribute the remaining valence electrons around each oxygen atom.

- Calculating the formal charges for each oxygen atom gives us:

- Oxygen 1: 6 - 4 - (4/2) = -1

- Oxygen 2: 6 - 6 - (4/2) = 0

- In this case, oxygen 1 has a formal charge of -1, while oxygen 2 has a formal charge of 0.

3. CH3−CH(OH)−CH

- The molecule contains one oxygen atom. It is part of an alcohol group (-OH).

- Oxygen in the alcohol group typically forms a single bond with a carbon atom (C) and has two lone pairs of electrons.

- Calculating the formal charge for the oxygen atom gives us:

- Oxygen: 6 - 4 - (2/2) = 0

- In this case, the oxygen atom has a formal charge of 0.

To summarize, the formal charges on the oxygen atoms in the given molecules are:

1. HPO42-: 0

2. CH3COO-: Oxygen 1 (-1), Oxygen 2 (0)

3. CH3−CH(OH)−CH: Oxygen (0)