Question

Write a plausible Lewis structure for \(\mathrm{NO}_{2}\), and indicate whether the molecule is diamagnetic or paramagnetic. Two \(\mathrm{NO}_{2}\) molecules can join together (dimerize) to form \(\mathrm{N}_{2} \mathrm{O}_{4}\). Write a plausible Lewis structure for \(\mathrm{N}_{2} \mathrm{O}_{4},\) and comment on the magnetic properties of the molecule.

Short answer

The Lewis structure for \(\mathrm{NO}_{2}\) includes an unpaired electron, rendering the molecule paramagnetic. In the case of \(\mathrm{N}_{2} \mathrm{O}_{4}\), the Lewis structure shows that all electrons are paired, meaning the molecule is diamagnetic.

Step-by-step solution

Lewis structure for \(\mathrm{NO}_{2}\)

Firstly, the total number of electrons in \(\mathrm{NO}_{2}\) is calculated by adding the valence electrons of Nitrogen (5 electrons) and Oxygen (6 electrons) twice, resulting in an odd number, 17 electrons. Therefore, \(\mathrm{NO}_{2}\) molecule will have an unpaired electron. A plausible Lewis structure will have Nitrogen in the center, connected by double bond to one Oxygen, and a single bond to the other Oxygen, with the unpaired electron on the Nitrogen.

Magnetic property of \(\mathrm{NO}_{2}\)

Since \(\mathrm{NO}_{2}\) molecule has an unpaired electron as seen from the Lewis structure, it would be paramagnetic.

Lewis structure for \(\mathrm{N}_{2} \mathrm{O}_{4}\)

The total number of electrons in \(\mathrm{N}_{2} \mathrm{O}_{4}\) is 32, calculated by adding the valence electrons of 2 Nitrogen (5 electrons each) and 4 Oxygen (6 electrons each). In the Lewis structure of \(\mathrm{N}_{2} \mathrm{O}_{4}\), the two Nitrogens are bonded together and each of them is attached to two Oxygens. Each Nitrogen has a bond with one Oxygen atom and two bonds with the other Oxygen, forming a resonance structure.

Magnetic property of \(\mathrm{N}_{2} \mathrm{O}_{4}\)

In the \(\mathrm{N}_{2} \mathrm{O}_{4}\) molecule, there are no unpaired electrons from the Lewis structure, implying that this molecule would be diamagnetic.

Key concepts

NO2 Molecule

The nitrogen dioxide (NO₂) molecule has a unique Lewis structure. To determine this, add the valence electrons of nitrogen (5 electrons) and oxygen (6 electrons each, for the two oxygen atoms), reaching a total of 17 electrons. Since it's an odd number, NO₂ contains an unpaired electron, causing the molecule to be paramagnetic. In the Lewis structure, nitrogen is central, with a double bond to one oxygen and a single bond to the other, leaving an unpaired electron on the nitrogen atom. This unpaired electron is key to the molecule’s magnetic properties. The presence of this lone electron contributes to paramagnetism, allowing NO₂ to be attracted to a magnetic field.

Understanding the Lewis structure helps explain the chemical and physical properties of the molecule, such as its reactivity and magnetic characteristics.

N2O4 Dimer

When two NO₂ molecules combine, they form dinitrogen tetroxide (N₂O₄), a process known as dimerization. In this scenario, NO₂ behaves like a building block, joining with another NO₂ to create a larger structure. The Lewis structure for N₂O₄ requires calculating the total electron count: 2 nitrogen atoms contribute 5 electrons each, while 4 oxygen atoms add 6 electrons each, summing to 32 electrons. In this structure, two nitrogen atoms are connected, with each bonded to two oxygen atoms.

One nitrogen holds a single bond and a double bond with oxygens, making it a resonance structure, meaning the molecule can be depicted in several ways while maintaining atom connectivity. This flexibility in electron distribution is typical in stable molecules. Since no electrons are unpaired in N₂O₄'s structure, it is diamagnetic, meaning it is not attracted to magnetic fields.

Magnetic Properties

Magnetic properties of molecules arise from their electronic structures. When we observe molecules like NO₂ and N₂O₄, understanding these properties involves considering the presence of unpaired electrons.

• **Paramagnetic Substances**: These have one or more unpaired electrons. NO₂, with its unpaired electron, falls into this category. As a result, it is drawn towards a magnetic field due to its paramagnetic nature.
• **Diamagnetic Substances**: These lack unpaired electrons. N₂O₄ is an example, as its electrons are all paired, thus making it unaffected by magnetic fields.

Recognizing these traits is crucial in fields like chemistry and materials science, where the magnetic behavior of compounds can inform both theoretical studies and practical applications.