Question

Draw a Lewis structure for nitric acid, \(\mathrm{HNO}_{3}\). The nitrogen atom is in the center, and the hydrogen atom is bonded to an oxygen atom.

Short answer

Nitrogen is central with double bond to one oxygen, and single bonds to two others (one with hydrogen).

Step-by-step solution

Count the Valence Electrons

Determine the total number of valence electrons in nitric acid by adding the valence electrons of each atom. Nitrogen has 5 valence electrons, each oxygen has 6, and hydrogen has 1. Thus, \(1 \times 1 + 1 \times 5 + 3 \times 6 = 24\) total valence electrons.

Arrange the Atoms

Position the nitrogen atom in the center. Connect the nitrogen atom to the three oxygen atoms. Attach the hydrogen atom to one of the oxygen atoms, as specified in the problem description.

Draw Single Bonds

Draw single bonds between nitrogen and each oxygen, and a single bond between one oxygen and hydrogen. This initial setup uses 4 bonds, consuming \(4 \times 2 = 8\) valence electrons.

Complete the Octet for Oxygen Atoms

Use remaining electrons to complete the octet of each oxygen atom. After forming single bonds, 16 electrons are left. Assign electrons to achieve octets for each oxygen keeping track of the total electron count.

Form Double Bond

To optimize electron distribution, form a double bond between nitrogen and one of the non-hydrogen-bearing oxygens. This will appropriately utilize the remaining electrons and maintain octets for the involved atoms.

Verify the Octet Rule

Check that each atom satisfies the octet rule (except hydrogen, which only needs 2 electrons). Nitrogen and each oxygen should have 8 electrons around them, completing the octet and sustaining charge balance.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial for chemical bonding. They are responsible for forming bonds between atoms. In the case of nitric acid (\(\mathrm{HNO}_3\)), we first need to calculate the total number of valence electrons.

• Nitrogen has 5 valence electrons.
• Each oxygen atom contributes 6 valence electrons.
• Hydrogen provides 1 valence electron.

Adding these, the total number of valence electrons in nitric acid is 24: \(1 \times 1 + 1 \times 5 + 3 \times 6 = 24\). These electrons are used in the bonding process to achieve stable electron configurations.

Octet Rule

The octet rule is a guideline in chemistry that states atoms tend to bond in such a way that they each have eight electrons in their valence shell. This creates a stable electronic arrangement similar to noble gases.
For the nitric acid molecule, achieving the octet rule ensures stability for the nitrogen and oxygen atoms while hydrogen only requires 2 electrons.

• Initial single bonds are formed to hold the structure together.
• The remaining electrons are distributed to satisfy each atom's octet requirement.

However, sometimes single bonds are not enough to satisfy the octet rule, leading to the formation of double bonds.

Nitric Acid

Nitric acid, \(\mathrm{HNO}_3\), is a strong acid widely used in industries such as fertilizers and explosives. Understanding its structure helps explain its reactivity and properties.
In its Lewis structure, the nitrogen atom is the central atom. It is connected to three oxygen atoms, and one of these oxygens is bonded to a hydrogen atom.

• The arrangement reflects the molecule's tendency to form stable bonds due to the octet rule.
• The hydrogen bond to one oxygen influences the molecule's reactivity, particularly in releasing hydrogen ions.

The double bond within the structure enhances stability by ensuring proper electron distribution.

Double Bond Formation

Double bonds are formed when two pairs of electrons are shared between two atoms. They play a crucial role when fulfilling the octet rule with single bonds is insufficient.
In the nitric acid molecule, after assigning single bonds, we use a double bond to help satisfy the octet rule.

• A double bond between nitrogen and one of the oxygens helps distribute the total of 24 valence electrons effectively.
• This electron arrangement ensures that each atom has the necessary number of electrons, maintaining stability.

Double bonds not only complete octets but also minimize formal charges, providing overall balance to the molecular structure.