(a) The nitrate ion, NO3^-, has a trigonal planar structure with the N atom as the central atom. Draw the Lewis structure(s) for the nitrate ion.

Verified step by step guidance

Step 1: Count the total number of valence electrons. Nitrogen (N) has 5 valence electrons, and each oxygen (O) has 6 valence electrons. Since there are three oxygen atoms, that's 3 x 6 = 18 electrons. The nitrate ion has a -1 charge, adding one more electron, for a total of 5 + 18 + 1 = 24 valence electrons.

Step 2: Place the nitrogen atom in the center and arrange the three oxygen atoms around it to form a trigonal planar structure. Connect each oxygen atom to the nitrogen atom with a single bond initially.

Step 3: Distribute the remaining electrons to satisfy the octet rule. Start by placing lone pairs on the oxygen atoms until each oxygen has a full octet. This will use up 18 electrons (6 for each oxygen).

Step 4: Place any remaining electrons on the central nitrogen atom. If the nitrogen does not have a full octet, consider forming double bonds by converting lone pairs from oxygen atoms into bonding pairs with nitrogen.

Step 5: Check the formal charges on each atom to ensure the most stable structure. Adjust the placement of double bonds if necessary to minimize formal charges, keeping in mind that the overall charge of the ion should be -1.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They help visualize the arrangement of electrons and the connectivity of atoms, allowing for a better understanding of molecular geometry and reactivity. In the case of the nitrate ion, drawing its Lewis structure involves determining the total number of valence electrons and distributing them to satisfy the octet rule.

Trigonal Planar Geometry

Trigonal planar geometry occurs when a central atom is bonded to three other atoms, with bond angles of approximately 120 degrees. This arrangement is a result of the repulsion between electron pairs, which positions them as far apart as possible. In the nitrate ion, the nitrogen atom is at the center, surrounded by three oxygen atoms, leading to this specific molecular shape.

Resonance Structures

Resonance structures are different ways of drawing the same molecule that illustrate the delocalization of electrons. In the case of the nitrate ion, resonance is important because it shows that the double bond between nitrogen and one of the oxygen atoms can be represented in multiple ways, indicating that the actual structure is a hybrid of these forms. This concept is crucial for understanding the stability and reactivity of the nitrate ion.

Recommended video:

Guided course

01:42

Resonance Structures

Related Practice

Textbook Question

The hypochlorite ion, ClO^-, is the active ingredient in bleach. The perchlorate ion, ClO₄^-, is a main component of rocket propellants. Draw Lewis structures for both ions. (c) What is the oxidation number of Cl in the hypochlorite ion? (d) What is the oxidation number of Cl in the perchlorate ion, assuming the Cl—O bonds are all single bonds?

Textbook Question

The following three Lewis structures can be drawn for N2O:

(a) Using formal charges, which of these three resonance forms is likely to be the most important?

Textbook Question

The following three Lewis structures can be drawn for N2O:

(b) The N—N bond length in N2O is 1.12 Å, slightly longer than a typical N≡N bond; and the N—O bond length is 1.19 Å, slightly shorter than a typical N═O bond (see Table 8.4). Based on these data, which resonance structure best represents N2O?

Textbook Question

Ortho-Dichlorobenzene, C₆H₄Cl₂, is obtained when two of the adjacent hydrogen atoms in benzene are replaced with Cl atoms. A skeleton of the molecule is shown here. (a) Complete a Lewis structure for the molecule using bonds and electron pairs as needed.

Textbook Question

Ortho-Dichlorobenzene, C₆H₄Cl₂, is obtained when two of the adjacent hydrogen atoms in benzene are replaced with Cl atoms. A skeleton of the molecule is shown here. (b) Are there any resonance structures for the molecule? If so, sketch them.

Textbook Question

Consider the hypothetical molecule B-A=B. Are the following statements true or false? (a) This molecule cannot exist. (b) If resonance was important, the molecule would have identical A–B bond lengths.