Textbook Question
For each of the following ions of nitrogen and oxygen, write a single Lewis structure that obeys the octet rule, and calculate the oxidation numbers and formal charges on all the atoms: c. NO2+.
Ch.8 - Basic Concepts of Chemical Bonding
Chapter 8, Problem 56b
Consider the formate ion, HCO2-, which is the anion formed when formic acid loses an H+ ion. The H and the two O atoms are bonded to the central C atom. (b) Are resonance structures needed to describe the structure?
Verified step by step guidance1
insert step 1> Identify the central atom in the formate ion, HCO_2^-. In this case, the central atom is carbon (C).
insert step 2> Draw the Lewis structure for the formate ion. Start by arranging the atoms with carbon in the center, hydrogen (H) and two oxygen (O) atoms bonded to it.
insert step 3> Count the total number of valence electrons available. Carbon has 4, each oxygen has 6, and hydrogen has 1. The negative charge adds an extra electron, making a total of 18 valence electrons.
insert step 4> Distribute the electrons to satisfy the octet rule for each atom, starting with the outer atoms (oxygen) and then the central atom (carbon).
insert step 5> Determine if resonance structures are needed by checking if there are multiple ways to arrange the electrons while maintaining the same arrangement of atoms. In the case of the formate ion, consider if the double bond can be placed between carbon and either oxygen atom, indicating resonance.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
6mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Resonance Structures
Resonance structures are different ways of drawing the same molecule that illustrate the delocalization of electrons. In molecules where multiple valid Lewis structures can be drawn, resonance helps to represent the actual distribution of electrons more accurately. The true structure is a hybrid of these resonance forms, which can affect the stability and reactivity of the molecule.
Recommended video:
Guided course
01:42
Resonance Structures
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 provide a visual way to understand how atoms are connected and the arrangement of electrons. For the formate ion, drawing the Lewis structure helps to identify the presence of resonance by showing how electrons can be distributed differently among the atoms.
Recommended video:
Guided course
04:28Lewis Dot Structures: Ions
Formal Charge
Formal charge is a concept used to determine the distribution of electrons in a molecule and to assess the stability of different resonance structures. It is calculated by taking the number of valence electrons in an atom, subtracting the number of non-bonding electrons, and half the number of bonding electrons. A lower formal charge on atoms typically indicates a more stable structure, guiding the selection of the most significant resonance forms.
Recommended video:
Guided course
01:53Formal Charge
Related Practice
Textbook Question
(b) With what allotrope of oxygen is it isoelectronic?
Textbook Question
Predict the ordering, from shortest to longest, of the bond lengths in CO, CO2, and CO32- .
Textbook Question
Consider a Lewis structure for SO3 that satisfies the octet rule. Which of the following statements is or are true?
i. SO3 has three equivalent resonance structures.
ii. There are one shorter and two longer S—O bond lengths in SO3.
iii. The S atom in SO3 has a nonzero formal charge.
Textbook Question
Which of the following statements about benzene, C6H6, is or are true?
i. Benzene has two equivalent resonance structures.
ii. There are no nonbonding pairs in the Lewis structure for benzene.
iii. Benzene has three short and three long C—C bonds.