Write the Lewis structure for each molecule (octet rule not followed). b. NO₂

Verified step by step guidance

1. Identify the total number of valence electrons in the molecule. Nitrogen (N) has 5 valence electrons, and each oxygen (O) has 6 valence electrons. Since there are two oxygen atoms, the total is 5 + 6*2 = 17 valence electrons.
2. Determine the central atom. In NO2, nitrogen is the central atom because it is less electronegative than oxygen.
3. Arrange the atoms with nitrogen in the center and the two oxygen atoms bonded to it. Initially, place a single bond between nitrogen and each oxygen atom.
4. Distribute the remaining valence electrons to satisfy the octet rule as much as possible. Start by placing lone pairs on the oxygen atoms to complete their octets.
5. Recognize that NO2 is an exception to the octet rule due to the odd number of electrons. Place the remaining electron on the nitrogen atom, resulting in a radical. Consider resonance structures where one of the N-O bonds is a double bond, and the other is a single bond, with the unpaired electron on nitrogen.

Key Concepts

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 use dots to represent valence electrons and lines to indicate bonds between atoms. Understanding how to draw Lewis structures is essential for visualizing molecular geometry and predicting reactivity.

Octet Rule

The octet rule is a chemical rule of thumb that states atoms tend to bond in such a way that they each have eight electrons in their valence shell, achieving a stable electron configuration similar to that of noble gases. However, some molecules, like NO2, do not follow this rule, leading to exceptions that require careful consideration of electron distribution and formal charges.

Formal Charge

Formal charge is a concept used to determine the distribution of electrons in a molecule and assess the stability of a Lewis structure. It is calculated by taking the number of valence electrons of an atom, subtracting the number of non-bonding electrons, and half the number of bonding electrons. A lower formal charge on atoms generally indicates a more stable structure, especially in cases where the octet rule is not followed.