Question

Write the correct Lewis structure and assign a formal charge to each atom in fulminate ion, \(\mathrm{CNO}^{-}\).

Short answer

The fulminate ion, \( \text{CNO}^{-} \), has C(-1), N(0), and O(0) with a Lewis structure having a triple bond between C-N and a single bond between N-O.

Step-by-step solution

Calculate Total Valence Electrons

To determine the Lewis structure of \mathrm{CNO}^{-}\, first calculate the total number of valence electrons. Carbon (C) has 4 valence electrons, nitrogen (N) has 5, and oxygen (O) has 6. The negatively charged ion adds 1 additional electron. So, the total is \(4 + 5 + 6 + 1 = 16\) electrons.

Sketch the Basic Structure

Arrange the atoms linearly as C-N-O. This sequence is often found in similar structures where nitrogen is the central atom or the linker between carbon and oxygen.

Place Electrons to Form Bonds

Use pairs of electrons to form bonds between C and N, and between N and O. Start with single bonds and then adjust with multiple bonds if needed to ensure each atom has a complete octet.

Complete Octets

Distribute the remaining electrons to ensure that each atom achieves an octet. Begin with the terminal atoms (C and O) and then address any deficiencies in the central atom (N). Here, attempt creating double or triple bonds if necessary to satisfy the octet rule.

Assign Formal Charges

Calculate the formal charge on each atom using the formula:\( \text{Formal Charge} = \text{Valence Electrons} - \text{Non-bonding Electrons} - \frac{1}{2}(\text{Bonding Electrons}) \).* Carbon: 4 - 0 - (3/2 * 2) = -1 * Nitrogen: 5 - 0 - (4/2 * 2) = 0 * Oxygen: 6 - 4 - (1/2 * 4) = 0

Structure Confirmation

The Lewis structure of \( \,\mathrm{CNO}^{-} \,\) is depicted with a triple bond between C and N, and a single bond between N and O. The formal charges are: Carbon (-1), Nitrogen (0), and Oxygen (0).

Key concepts

Formal Charge

The concept of formal charge is essential when drawing Lewis structures. It helps us determine the most stable arrangement of electrons around atoms within a molecule or ion. Formal charge is calculated using the formula:

• Formal Charge = Valence Electrons - Non-bonding Electrons - 1/2(Bonding Electrons)

The goal is to have the formal charge as close to zero as possible for each atom. The more energetically favorable structure is usually the one with the smallest absolute value of formal charges.
In the case of the fulminate ion, \( \mathrm{CNO}^{-} \), proper assignment of formal charges reveals carbon has a formal charge of -1 while nitrogen and oxygen both have charges of 0. This distribution of charges is significant in showcasing the stability of the fulminate ion structure, which satisfies the octet rule as well.

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom, and they play a crucial role in bond formation. These electrons are responsible for the chemical properties of the element. To construct a Lewis structure, you need to account for all valence electrons present in the atoms making up a molecule or ion.

• Carbon (C) has 4 valence electrons.
• Nitrogen (N) has 5 valence electrons.
• Oxygen (O) has 6 valence electrons.

For the fulminate ion, \( \mathrm{CNO}^{-} \), considering the additional electron due to its negative charge, the total count of valence electrons becomes \(4 + 5 + 6 + 1 = 16\). Arranging these electrons according to the octet rule helps us form the bonds within the ion.

Fulminate Ion

The fulminate ion, \( \mathrm{CNO}^{-} \), is an interesting structure to study because of its reputation in explosive chemistry, yet it also serves as an excellent example for visualizing formal charges and electron sharing in a Lewis structure. In its structural arrangement, carbon, nitrogen, and oxygen are aligned in a linear format.
The triple bond between carbon and nitrogen, and the single bond between nitrogen and oxygen depict how the electrons are shared equally while maintaining the overall negative charge of the ion. Each atom in the fulminate ion ends up with a nearly complete or full octet, important for the ion's stability.

Octet Rule

The octet rule is a key principle in chemistry that helps explain how atoms form bonds. It indicates that atoms tend to share or transfer electrons in such a way that each atom involved usually has eight electrons in its valence shell, resembling the electron configuration of a noble gas.
In drawing the Lewis structure for the fulminate ion, \( \mathrm{CNO}^{-} \), you must arrange the atoms and electrons to satisfy the octet rule wherever possible.

• Carbon achieves a full octet through a triple bond with nitrogen.
• Nitrogen is the central atom, bonding with both carbon and oxygen, thus reaching its octet condition.
• Oxygen gains its octet by having two lone pairs and sharing two electrons with nitrogen.

This abidance of the octet rule in the Lewis structure of the fulminate ion explains its stability and electronic configuration.