Question

Draw Lewis structures for hydrazoic acid (HN \(_{3}\) ) that show all resonance forms.

Short answer

Question: Draw the Lewis structures for hydrazoic acid (HN3) that show all the resonance forms and explain each step. Answer: To draw the Lewis structures of hydrazoic acid (HN3), we follow these steps: 1. Identify the central atom and total number of valence electrons. Nitrogen (N) is the central atom, and there is a total of 8 valence electrons. 2. Draw a skeletal structure connecting all atoms with single bonds. It looks like H-N-H with a nitrogen atom connected to the central nitrogen. 3. Place the remaining electrons on the nitrogen atom. One electron goes to the nitrogen atom, and five electrons form a lone pair. 4. Identify and draw resonance structures. There are two resonance structures for HN3: Resonance Structure 1: H-N=N-N (One single bond between the first N and H and a triple bond between the first and second N. The second N has a single bond to the third N.) Resonance Structure 2: H-N-N=N (One single bond between the first N and H. The first N has a single bond to the second N, then a triple bond between the second and third N.)

Step-by-step solution

Identify the central atom and total number of valence electrons

To draw the Lewis structure of hydrazoic acid (HN3), we first need to identify the central atom. Since there is only one nitrogen (N) and three hydrogen (H) atoms, nitrogen is the central atom. Next, we need to calculate the total number of valence electrons. Nitrogen has 5 valence electrons and hydrogen has 1 valence electron. So, the total number of valence electrons is 5 + 3 * 1 = 8.

Draw the skeletal structure of hydrazoic acid

We will start by connecting all the atoms with single bonds. Place the nitrogen (N) atom in the center, and connect the three hydrogen (H) atoms to it. The skeletal structure will look like H-N-H. Since nitrogen has 5 valence electrons and there are three hydrogen atoms, two of those electrons will go into the single bonds, leaving 6 valence electrons for nitrogen.

Place the remaining electrons to the nitrogen atom

Six electrons must be placed on the nitrogen atom. Therefore, we will give one electron to the nitrogen atom and five electrons will form a lone pair. The current Lewis structure for hydrazoic acid looks like this: H-N-H | N

Identify and draw resonance structures

We can now draw all possible resonance structures that follow the octet rule. There are two possible resonance structures for hydrazoic acid (HN3): Resonance Structure 1: H-N=N-N - One single bond between the first N and H and a triple bond between the first and second N. The second N will have a single bond to the third N. Resonance Structure 2: H-N-N=N - One singe bond between the first N and H. The first N has a single bond to the second N, then a triple bond between the second and third N. These two resonance structures represent all possible structures of hydrazoic acid that follow the octet rule.

Key concepts

Resonance Forms

Resonance forms in chemistry refer to different possible structures of the same molecule that result from the delocalization of electrons. These structures help portray the flexibility and real electron distribution more accurately.
For example, in the case of hydrazoic acid (HN\(_3\)), there are multiple ways the electrons can be arranged while maintaining the overall connectivity and number of valence electrons.

Even though individually drawn structures like H-N=N-N and H-N-N=N might look distinct, they represent the same molecule and a true picture of the molecule is a hybrid of these forms.
The actual structure of hydrazoic acid is a blend of all possible resonance structures. It's crucial to remember that these are not separate, different molecules, but rather expressions of the same molecule indicating electron delocalization.
Using resonance forms allows chemists to better explain properties such as stability and reactivity that are not adequately described by a single Lewis structure.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are primarily responsible for the chemical properties of an atom, including its bonding behavior.
When drawing Lewis structures, we first consider the valence electrons to determine how atoms can bond with each other to form molecules.

In hydrazoic acid, the nitrogen atom has 5 valence electrons, while each hydrogen atom contributes 1 valence electron.
These valence electrons form the backbone of how the atoms are connected in the Lewis structure. By totaling the number of valence electrons from all involved atoms, you can predict the bonding arrangement.
In the case of HN\(_3\), the total number of valence electrons is 8, setting the stage for how they might share these electrons to form stable bonds and possibly engage in resonance forms.

Central Atom

The central atom in a molecule is typically the atom with the highest bonding capacity or the ability to form multiple bonds. It's the atom around which other atoms are organized in the structure.
In the case of hydrazoic acid (HN\(_3\)), nitrogen is the central atom. This choice is guided by nitrogen’s ability to form multiple bonds and its higher electronegativity compared to hydrogen.

Identifying the central atom is crucial as it establishes the framework for building the rest of the Lewis structure. All other atoms are placed around this central atom, maximizing bonding potential.
Once the central atom is chosen, subsequent bonding can follow, allowing for the correct depiction of the molecule in relation to its molecular geometry and potential for resonance.

Hydrazoic Acid

Hydrazoic acid is a chemical compound with the formula HN\(_3\). It is interesting because of its unique and reactive nitrogen chain.
This molecule's Lewis structure involves a nitrogen atom bonded to hydrogen and other nitrogen atoms, showing the potential to form various resonance structures.

The different resonance forms of hydrazoic acid highlight how flexibility in electron distribution can stabilize the molecule, despite having unstable bonds overall.
Even though hydrazoic acid is less commonly encountered, understanding its Lewis structures and resonance forms provide invaluable insights into complex nitrogen coordination.
Such nitrogen chains and resonance considerations are fundamental in broader chemical contexts, shedding light on both organic and inorganic chemistry phenomena.