Question

Assign oxidation states to all of the atoms in each of the following: a. \(\mathrm{NH}_{3}\) b. \(\mathrm{CO}\) c. \(\mathrm{CO}_{2}\) d. \(\mathrm{NF}_{3}\)

Short answer

The oxidation states of the atoms in the given compounds are as follows: a. \(\mathrm{NH}_{3}\): N=-3, H=+1 b. \(\mathrm{CO}\): C=+2, O=-2 c. \(\mathrm{CO}_{2}\): C=+4, O=-2 d. \(\mathrm{NF}_{3}\): N=+3, F=-1

Step-by-step solution

Assign oxidation states for \(\mathrm{NH}_{3}\)

In \(\mathrm{NH}_{3}\) (ammonia), nitrogen (N) is bonded with three hydrogen (H) atoms. Hydrogen has an oxidation state of +1. Therefore, the oxidation state of the nitrogen atom should be such that the sum of oxidation states is equal to the overall charge of the molecule (in this case, neutral): \[ (+1) \times 3 + x=0 \] \[ x=-3 \] So the oxidation states in ammonia are: N=-3, H=+1.

Assign oxidation states for \(\mathrm{CO}\)

In \(\mathrm{CO}\) (carbon monoxide), carbon (C) is bonded with one oxygen (O) atom. Oxygen usually has an oxidation state of -2. Therefore, the oxidation state of the carbon atom should be such that the sum of oxidation states is equal to the overall charge of the molecule (again, it's neutral in this case): \[ x + (-2)=0 \] \[ x=+2 \] So the oxidation states in carbon monoxide are: C=+2, O=-2.

Assign oxidation states for \(\mathrm{CO}_{2}\)

In \(\mathrm{CO}_{2}\) (carbon dioxide), carbon (C) is bonded with two oxygen (O) atoms. Oxygen usually has an oxidation state of -2. Therefore, the oxidation state of the carbon atom should be such that the sum of oxidation states is equal to the overall charge of the molecule (once more, neutral): \[ x + 2\times(-2)=0 \] \[ x=+4 \] So the oxidation states in carbon dioxide are: C=+4, O=-2.

Assign oxidation states for \(\mathrm{NF}_{3}\)

In \(\mathrm{NF}_{3}\) (nitrogen trifluoride), nitrogen (N) is bonded with three fluorine (F) atoms. Fluorine has an oxidation state of -1. Therefore, the oxidation state of the nitrogen atom should be such that the sum of oxidation states is equal to the overall charge of the molecule (which is neutral): \[ x + 3\times(-1)=0 \] \[ x=+3 \] So the oxidation states in nitrogen trifluoride are: N=+3, F=-1.

Key concepts

Oxidation Number

Oxidation numbers, or oxidation states, are crucial for understanding redox reactions and molecular properties. They help determine the charge distribution within a molecule. Each element in a compound is assigned an oxidation state to balance the entire charge of the compound to zero unless specified otherwise.

• For example, hydrogen usually has an oxidation number of +1, and oxygen typically has -2.
• These assignments help chemists identify electron transfer and bonding types between atoms.

Using oxidation numbers, we can easily balance chemical equations and study the changes that occur during reactions.

Chemical Bonding

Chemical bonding is the force that holds atoms together within a compound. Various types of bonds can form, including ionic, covalent, and metallic bonds.

• Ionic bonds occur when electrons are transferred from one atom to another, typically between metals and non-metals.
• Covalent bonds form when atoms share electrons to achieve stability, often seen in non-metal compounds.

Understanding bonding helps us predict molecular structure, reactivity, and properties.

Molecular Charge

Molecular charge refers to the net charge of a molecule, indicating whether it's positive, negative, or neutral. It's determined by the sum of oxidation states within the molecule.

• In neutral molecules, like those in this exercise, the total oxidation states add up to zero.
• If a molecule has an ion, the charge reflects the difference in the number of protons and electrons.

Molecular charge affects solubility, reactivity, and interaction with other molecules.

Ammonia

Ammonia ( NH_3 ) is a simple yet essential molecule. It's composed of one nitrogen atom bonded to three hydrogen atoms.

• Nitrogen has an oxidation state of -3 in ammonia, while each hydrogen has a state of +1.
• This neutralizes the overall charge, confirming a stable configuration.

Ammonia is widely used in fertilizers, cleaning products, and as a refrigerant.

Carbon Monoxide

Carbon monoxide ( CO ) is a diatomic molecule, consisting of one carbon and one oxygen atom.

• In CO, carbon has an oxidation state of +2, while oxygen is -2.
• This molecule is neutral and incredibly stable but can be harmful as it binds with hemoglobin in blood.

Understanding CO’s oxidation states is vital for studying combustion and environmental chemistry.

Carbon Dioxide

Carbon dioxide ( CO_2 ) is a linear molecule made up of one carbon atom double-bonded to two oxygen atoms.

• The carbon has an oxidation state of +4, and each oxygen is -2.
• This balance forms a neutral and stable molecule.

As a product of combustion and respiration, CO2 is crucial for life and climate studies.

Nitrogen Trifluoride

Nitrogen trifluoride ( NF_3 ) is a molecule consisting of one nitrogen atom bonded to three fluorine atoms.

• Here, nitrogen has an oxidation state of +3, while each fluorine is -1.
• These states balance the overall charge, making it a neutral compound.

NF3 is used in various industrial applications, such as semiconductor manufacturing and plasma etching.